1/16 Scale FrankenDiff

[ddmckee54]

I'm going to be doing several Bruder conversions in the near future, since I'm retiring next week. I don't have the skill to scratch build, and I like the idea of using the Bruder stuff as a starting point. Bruder at 1/16 scale really doesn't look right when you use 1/14 scale running gear, plus the cost of the running gear is more than I'm willing to spend.

Soooo... my wandering mind latched onto the idea of Frankensteining a reasonable looking truck rear end out of other available low-cost bits. I probably got the idea from "mick thebass" on YouTube when he modified a couple of low-buck 1/12 scale WPL diffs and used them on his articulated Bruder dumper. He did some really neat stuff if you haven't checked him out. He hasn't updated his channel for a couple of years so I'm afraid he might not be with us anymore - which is too bad. The guy was a master at stuffing 10 pounds into a 5 pound sack.

I thought about using the Kong 1/12 scale diff, even got one to see if it'd work. It's a GREAT looking axle, smooth as silk, about the right size, and the price isn't too bad. But as far as I know they only make the rear axle version, they don't make a center axle version. I don't know about you guys, but the thought of building a truck that's SUPPOSED to have double drivers, and then having one axle sitting there doing nothing doesn't appeal to me.

So, back to the Frankendiff. I'm starting with your basic plastic diff for a WPL 1/12 scale car, it's guts are about the same size as the Kong axle. The actual axles will need to be shortened, but that'll be fairly simple machining to cut them to length, turn down the ends, thread them M4, and drill new holes for the drive pins. I'm just going leave it an open diff for now, no lockers.

Nope, the complicated part is the 3D modelling of the front and rear halves of the differential housing so that the WPL guts will fit into them. (While simultaneously learning Alibre, I use-ta-use Designspark3D.) The pinion housing is the most complicated part and I re-did that last night - I was NOT happy with the first attempt. I think I should be able to get the rear cover done tonight, it's pretty simple.

Then I'll 3D print a prototype and see what parts need to be fixed. I'll take some pictures when I've got some physical parts.

Eventually I'd like to cast the parts in ZA-12, both for durability and the extra weight. (But plastic will do for now.)

[Zabco]

Welcome to the good life. I was able to take early retirement 8 years ago and I have enjoyed every minute of it. What got me into this hobby was the fear of 'what am I going to do with all this time' after averaging 50+ hours a week for the last 30 years. Has not been a problem. Get to do everything I like to do, research, design, build, play with electronics, play with machining, experiment with new methods, etc, etc, etc. Most weeks, come Friday, I wonder where the time went.

See you apparently decided to go with Alibre as your 3d cad program. It's been a good program for me, hope you enjoy it.

[ddmckee54]

Zabco:

I went with Alibre for a couple of reasons, you can get a perpetual license, and you can get an off-line version of that license - one that doesn't need to phone-home every 30 days. I refuse to rent a cad package, and I also refuse to let somebody else hold my files hostage. I pulled the trigger on the Alibre purchase this morning, only had 4 days left on the trial. I've REALLY got to learn Best Practices, and actually use them, instead of just poking and prodding at it like I have been.

I printed out a prototype of the front half of the diff to see how things fit. Let's just say that my measurements were apparently less than accurate. Or at least my 3D model is less than accurate. I guess I got some 'slpainin to do to it. Over the weekend I hope to get to the point where the WPL guts will fit between the front and rear halves of the diff.

I left side to side clearance for fit of the pinion to ring gear, as well as front to back clearance for the pinion to ring gear. I figured I'd print a prototype and let the diff find its' happy spot, then measure how much I needed to adjust the model.

I've definitely got a problem with the diff carrier bearing fit - they don't. Looks like I measured the bearing ID and OD, then drew the 3D model using the ID dimension instead of the OD.

Then I've got this STUFF in the middle of the axle itself, that I can't for the life of me figure out WHY it's there. On both axles there a hole with a very short pin inserted in it, imagine a 6mm long pin through a 5mm axle and you've got the picture. I'd include a picture, but that axle is at home and I'm NOT. There's a plastic collar that slips over the pin and retains it, but the pin also limits how close the outboard edge of the collar can get to the diff carrier. Just outboard of that junk is a plain bushing, yup - a bushing. There are bulkheads on both sides of the bushing fixing it in place. The inboard bulkhead also does a very rough job of limiting the side to side position of the diff assembly by limiting how far outboard that plastic collar can move.

I can't think of ANY good reasons why the crap is there. The best explanation I can think of is that WPL uses this assembly in other differentials and it's needed in that other application. We all know that WPL uses bits and pieces from this model and that, slaps them together, and calls them a new model. In the next round of design I'm going to chuck all that crap in the middle of the axle into the trash-can and see if anything breaks. I've still got bearings supporting the diff carrier and bearings on the outboard ends of the axles. That's all that most full-size cars and light trucks have. If it's good enough for them it's good enough for me.

It's supposed to be rainy Saturday night and Sunday, we'll see what I can get done on the Frankendiff.

[Zabco]

Same reasons I went with Alibre also.

Yep, bearing support for axle shafts in middle and end should be only thing you need. That's all the Tamiya rear ends have and they seem to hold up just fine to all sorts of abuse.

[ddmckee54]

I got some stuff printed out over the weekend. It's been a while since I created a new album, I THINK I've got it set for sharing, let me know if I remembered all the hoops I need to jump through so that anybody else can see the photo.
https://photos.google.com/share/AF1QipOdNZY_KfreRAk1c2k_xeZNi6Gfa2Fw1s8UsgoqFkOsue fT9OSMoT-pwiJGrcE5oA/photo/AF1QipNiKgq0yBIG8Ela_9GYYFqRPu8PFF8onAlkEDc-?key=b092aTR2SzBhREdoQ3U5X2g1cjl0RnQ5b3hWdnVR

What you are hopefully seeing is the front and rear halves of the diff housing screwed together, along with the pinion housing screwed on the front. I've lost track of the number of times I've printed the diff halves, definitely more than I can count on one hand, even if I was the 6-fingered man. I was having bed adhesion problems at first, it's been a while since I printed anything. But I DID dust the bed off first, that just wasn't enough. That was Round 1.

Then it JUST wasn't measuring up, too small. That was Round 2. Yeah, I forgot to scale it up in the slicer - it's been a while since I printed anything. I scaled it to 103% in the slicer and printed Round 3. Hoo-Boy-Howdie Round 3 measured at 120.18mm, close enough to 120mm for me. Do the guts fit....NOPE. How come, the ring gear has a 25mm OD and it's in a 26mm hole, it should fit. IF the ring gear was centered in the opening it would fit, but when the ring gear is offset from center - not so much.

Re-design the diff carrier space in the front and rear diff halves and re-print - Round 4. Things were looking up after Round 4, outside dimensions checked out OK, the donor diff guts and bearings appeared to fit in their respective pockets. Will the front and rear halves fit together? NO, the diff halves do not fit together!!!!!

I started measuring the bearing pockets, since the bearings are the only things that could be keeping the case halves from mating together. The bearing measurements and the model measurements match. I don't like either of the explanations that I was able to come up with; 1) either the slicer is doing something funky when it's scaling the part, or 2) the part isn't shrinking linearly.

The only thing I could think of was to start tweaking bearing pocket dimensions and see if that worked:
Round 5 - too small.
Round 6 - better but still too small.
Round 7 - WHOOOPS - over-compensated.
Round 8 - Sorta worked. The diff halves do clamp together, but the axles not longer turn as easily as they used to turn. I wondered if I was clamping the bearings too tightly? I backed off the screws and sure enough things started turning easier. It's hard to believe that a pair of M2 sheet metal screws and a 2 piece plastic clamp could apply enough pressure to load the bearing shells like that. I'll tweak the pocket dimensions one more time and try Round 9 tonight.

Don

[Zabco]

When you create the .stl file from your 3d model in alibre a stl configurations box should pop up. Make sure and use a value no greater than 1 degree for the faceting parameters setting. stls do not contain true circles, only straight lines. A value of 1 degree would create a circle comprised of 360 straight lines. If your faceting was set to say 6 degrees then the circle would only consist of 60 lines. The lines would be longer but more importantly the center distance between two opposing lines (the diameter of your circle) would be less than the desired diameter. This would compress your bearing when you tightened up the two axle halves.

[Blender]

Awesome you took the CAD plunge. Alibre was at the top of my list too.


Id wager your printer is culprit. Some are better than others. Should be able to tune scaling in each direction. I've never totally solved it. Bearing pockets need a pretty tight fit. The slight compression of each layer squeezes it a bit wider.

3D printing is certainly a bit more involved than push button, receive part.

Is it possible to assemble the axle halves, and thru drill/ream the bearing pockets? Or are the end opening too small?

[frizzen]

With your growing lack of tolerance for fighting the printed part tolerances: What if you rough assembled the axle guts, moderately warmed them with a heatgun, and tried to close the axle case halves around them? Let the parts soften and clearance what they need, then you can evaluate where it made marks.

Which style WPL axles actually have a Differential instead of Spool?
I had wondered how much the extra bearings in the wpl axles was there to stiffen up the cases instead of support the axles?

[ddmckee54]

Nice discussion we've got going on here, deeply appreciated.

Blender:
I use Simplify3D for my slicer and I can scale all the axis independently if I want. I've tweaked the basic setup of the printer, it's a Wanhao D6 clone by Monoprice, so that I get accurate external dimensions. The diff halves should measure 120mm across, the circular part of the housing should have a 37mm OD and it should be 7mm thick, they measure 120.18mm, 36.98mm, and 7.21mm respectively. The first 2 are close enough for me. I'd like to get the Z height a little closer, but since my version of S3D does not allow for variable layer thickness, I've got to accept that the thickness could be off by a layer thickness, 0.2mm is what I'm currently printing at. External is fine, it's the internal pockets that are the problem. Drilling/reaming the 9mm outer bearing race pockets wouldn't be a problem. The only way I could see to get to the inner 12mm pockets would be some sort of line boring set-up, and I've only got the 6mm hole for the axle to work through.

Zabco:
I've been using the default set-up for the STL's, which I think is 4 degrees. Since I've been poking and prodding at all 4 of the parts, and have to reprint them all, I'll look at making a higher resolution STL.

Frizzen:
This is a replacement WPL diff for the "1:16" scale trucks.
https://www.ebay.com/itm/226181753781?_skw=wpl+b36+diff&itmmeta=01J8JXSMDCHVJ0H4E6NZMMC64N&hash=item34a97babb5:g:xO0AAOSwlmNmYtKC&itmprp=enc%3AAQAJAAAA0HoV3kP08IDx%2BKZ9MfhVJKlm3Au 1GEoveYNjPtz9F02fshd1rhE8DpJ6mk0fkErAtiFqIW9udd96r zVd9YOJIigaHtBsw8zrmOfx5MCRe1ScLpuAQEMvwiULTedDmIC H%2FKmhK1VAMZ3oQWAF5C3nwVtBvXLEBgabMOZ17Bat2OGlZ4m hPTDSF9y3QRoFusif6yFjx%2FebYI%2FTY4cVCJN0eG%2BqEFr 7WOcRSBOoOuzr9vYRgX6NYDYE6J3I94fTLjWkTarDkJwvGG5f7 H08LaXe34k%3D%7Ctkp%3ABk9SR-DG5t3EZA

I don't remember the exact part number, but this is REALLY similar to what I am using for a donor axle.
https://www.ebay.com/itm/204852249342?_skw=wpl+12428+axle&itmmeta=01J8JXR263XGD2N7S76TC86GAW&hash=item2fb22542fe:g:jSYAAOSwUpFmeiLT&itmprp=enc%3AAQAJAAAA8HoV3kP08IDx%2BKZ9MfhVJKkbbJr v5oguu7UMDNc%2BcL9PpK%2FLcJZaQwX6EY8R8iEUD%2BewjYL jfRtbIR1XtOpt7pOFTC6RZdF0Z1W81P%2BPkIVncYO6qzz9sKH EZu%2BudsTCYg5xGUCgxjLSARdNn94cpASJ1RGjE4cq6Eexe4C SBGdYGcPwr6tAceWZIEKWdWew7EK8wz5abx%2B3dYOHQorSOe% 2BXk%2BLrY0dIr98CVUv0EoLZ8%2BCeH%2BmpoGu2xSF4vWK0q AwZextelyUxNRzH34Bq5lzyMNS3w99f5k8BrnHLVRF0qB%2Bcl NagF8N2t0wVBiSFLw%3D%3D%7Ctkp%3ABFBMkKPg3cRk

[ddmckee54]

Two steps forward, one step sideways, and one step back.

I measured all of the internal pockets on the diff halves, they were ALL consistently about 97.4% of the model size. That's the size I would expect them to be when you allow for shrinkage. I'm beginning to wonder if my version of S3D scales internal dimensions? I really need to try scaling the slicer to about 150% and see what the pockets look like then as an experiment - without printing anything.

Anywho... I scaled the critical pocket dimensions to 103% in the model, the same as my scaling factor in S3D and printed the diff halves again - things are REAL close. The inner bearing pockets are a little bit too tight, and the outer bearing pockets are a little too loose. When I tighten all the screws holding the halves together the outer bearings will slip out of the pocket, and the inner bearings will not turn freely - but I think that's MY fault.

The outer bearing pocket dimension when scaled was 4.84mm and change, I just rounded it up to 4.85mm. The inner bearing pocket dimension when scaled was something like 6.12mm and change, I just rounded it down to 6.1mm. I'm going to print this one more time, but this time I'm going to round the pocket dimensions to the 3rd decimal place and see how that works.

Don

[Blender]

Getting close! Almost every FDM printer I've used will make IDs too small. Normally I drill them out. Even the industrial printer's SLA parts I've ordered are a bit of a wildcard in term of tolerance.


When bearing pockets are too big, I'll do a single wrap of tape on the outside before installation. Tape choice based on how far out the pocket it maybe scotch, maybe painters tape. I'm also not above a drop of CA glue either.

[ddmckee54]

Something just didn't feel right to me, I had play in the pockets up and down, but not from front to back. So I got out the Opti-visor and gave things a look-see.

In most of the pockets there was a booger about 1-3mm wide in what would be the top of the arch when the pockets are printed. This area would be the bottom side of a bridge when printing. My printer does pretty good, but the bottom of the first layer of a bridge is NEVER pretty.

My current plan is to increase the radius about a 0.5mm in that area. I'll still get a booger when the printer bridges in that area, but the booger shouldn't be touching the bearing any more. And since I'm measuring about 0.2mm of total play I'll reduce the radius of the bearing pocket by about 0.1mm.

I've got a problem with the pinion housing's print too, turns out I'm trying to print a circular opening in a horizontal surface in mid-air. (Without support) That NEVER works out for me - should have seen that one coming.

Don

[ddmckee54]

OK, I have a mostly functional 3D printed Frankendiff. I modified the bearing pockets, as described above and that eliminated the booger caused by the bridging layer. Scaling the bearing pocket diameters to 3 decimal places instead of rounding them to 2 places seems to have cured the bearing fit problem in the diff housing.

I added a couple of fillets to the cut-out for the inner bearing in the pinion housing and printed it again - it didn't fit right. That was really no surprise since I couldn't get a good measurement of the depth to the inner bearing pocket. So I just guessed - I was about 0.75 mm too shallow. Well that didn't work as planned either, that extra 0.75 mm of cut depth managed to break through to the outside. When I fixed that, that fix broke almost ALL of the fillets to the rest of the housing.

By the time the shouting was over I had basically re-designed the entire diff. But it looks much prettier now, and the 3D model is a LOT simpler. Before it just looked, I don't know - chunky/clunky? It more closely resembles the Kong axle now, except that I can make a center axle out of mine by getting a replacement pinion and the bearings, and printing another pinion housing.

[Zabco]

Congrats!

[frizzen]

Sounds like it's been good practice. Any pics of the diff housings through the learning curve?

Thanks for the tip on those parts.

[ddmckee54]

Pictures.... about that, there's been a hiccup.

I retired about a week ago and I've discovered since then that I REALLY depended on those work computers. Almost all of the forums that I'm a member of were pointed to those e-mail addresses, and those high-speed morons were remembering the passwords for me. Those computers are no longer accessible to me now. I think I've worked my way through most of the forums now, but I'm still working on getting back into my pictures.

Regarding the donor axles, right out of the box they are about what you'd expect from cheap Chinese knock-offs. Let's just say not very good, as in really crunchy. You can BARELY turn the pinion shaft on them. When I opened up the first one I found that the ring gear and the pinion gear are both die-cast. They both had been very crudely clipped off their sprues - with no effort made to clean off the sticky-outy bits. Cleaning those nubbins off and getting the pinion depth set made a huge difference.

It's still a little crunchy when I make the diff work. I'll probably have to look at the spider gears next, since they are also probably die-cast. And probably just as rough as the ring and pinion were. I'll have to tear the diff apart anyway when I machine the axles to length.

Don

[Zabco]

Yea, practically every web site wants a login anymore. Way too many user ids and passwords to keep track of. I created a spreadsheet to keep track of them and it's probably the most often opened file on my PC, but an absolute lifesaver.

[ddmckee54]

Mine's a text document, with a very obscure name, that's on a thumb drive which never leaves my possession.

My work computers used to require us to change our password every 90 days. You couldn't repeat more than a small number of consecutive letters from your old password, and you couldn't reuse any of your last 12 passwords. I kept the list of my old passwords in the same document.

[ddmckee54]

Pictures, I think I've got pictures - if I can just decode how to insert them.

https://lh3.googleusercontent.com/pw/AP1GczNIZNR9KYSF2A1JS0yod87BcAhgS3wCRHL4PUo1YT7mlr Cpk2mWkVh5no0y1SSADFTihWqGxQ7U2HHBi6AAJP3D_lMgUZdm p2dsdDx-yk0gJuzdlIK1oEcqCEOKXaQyztmrDmpM7h-z-aREeIkwmVGH=w426-h568-s-no?authuser=0
If this works, you should be able to see the Frankendiff Mk-I. Well that seems to have worked. This was the 1st version of the diff, and it looks OK - just kinda mmeeehhhh.

Enter the Frankendiff Mk-II.
https://lh3.googleusercontent.com/pw/AP1GczNKzFctIEpYng9e5ZoA1_L3csClYoWev98LIPIDH_ikll VE2tNdkGJeKo0XAMhuzMKYSF7MuCL1n-AqhE507eJew5K3bzji84FrR_3NW3wGWOA_TJ96bzJ-IvqaS6r18b4qTzBRiZIfijHoOMg1UeCf=w640-h480-s-no?authuser=0
This is the current version, and it looks more like the Kong diff which will be in the next image.

https://lh3.googleusercontent.com/pw/AP1GczPZ6QWT4C3wmS0Wa1T5kGewZg_Tz6QAvicN92F9YC5Jf8 j-usJ4QLrHzzdIeENvHXblLWPMOYVbM8aKrq2nRDlv9H6GcVLj14 Ke7Fraee4PyALnGeVEMG0DZvlD0UjWEOQmZQBnenvSlsm3jTC7 G3ai=w640-h480-s-no?authuser=0

I initially called this my Wall of Shame, but it's more a collage than a wall. On the left side from bottom to top you have:
1 - The MK-I front diff housing. If you look closely you can see that I have recessed pockets for the screw heads, more on this later.
2 - The Mk-I rear diff housing. It's ALMOST identical to the front half, except the mounting screws go into blind holes.
3 - This is the final version of the Mk-I diff. Everything fits, and it WOULD have worked - it just looks like something you could build out of a box of Tinker-toys.
4 - At the head of this column is the Kong axle, the thing that started this journey into madness. It's a nice axle, and at $A40-$50 USD fairly cheap. But it's unobtainium as a center axle.

Just to the left of the Kong axle is the back-side of the Frankendiff MK-II. I took the rear cover off so you could see that I also re-designed the ring-gear/diff pocket for the Mk-II. The Mk-I housing would allow a noticeable gap to show at the top and bottom of the center section. The Mk-I's rectangular diff pocket didn't give me any place to correct that gap. The Mk-II's diff pocket gave me room to stash 2 more screws under the pinion housing, closing up those gaps.

What are the differences between the Mk-I and the Mk-II! A LOT, but with the exception of the 2 extra screws in the center section all the changes were just to make it look better. I slimmed the diff halves by a total of 2 mm, then added pads on the outer ends like the Kong diff has. That meant I had to redesign the pinion housing and the rear cover to compensate for the 1 mm change on each side. I also got rid of the recessed pockets, nothing like a full-sized mockup to show where you need to make better choices.

The bottom row on the right side is the pinion housing iterations, these were:
1 - The oldest version - the bearing pocket ID's were too small. I also had recessed pockets for the screw heads. It looked good on the screen - real-life, too thin.
2 - The next version - the bearing pocket ID's were too big.(Round off error, my fault. Also got rid of the recessed pockets.)
3 - The next to the last version - the outer bearing pocket fit just fine, the inner one not so much. 3D printers just REFUSE to properly print something when it starts in mid-air. The latest version is still screwed onto the Mk-II diff.

The next row on the right side is the rear cover iterations, left to right:
1 - The oldest version - just didn't look right, it needed something.
2 - The next version - I added a boss. Why's it need a boss? For the drain plug silly! (Didn't print well, that starting to print in mid-air thing again.)
3 - The last version - including the drain plug.

In the upper RH corner is my latest descent into madness - hubs, wheels, tires, and unseen but holding up the wheel is the front axle that will be donating its' spindles/knuckles. The doo-dad that looks like a brake drum is the 1st iteration of the front hub, as usual the bearing pockets were too small. I overcompensated on the next version, but it was close enough that I could shim it with a piece of tape to put everything together. It looks good- and it would work. But the effort needed to get the 3 parts lined up to start that dinky little M2 screw was enough to convince me to make the wheel and hub 1 part - with a separate cover to hide the M4 Nylock nut.

The tire you see is the Lesu 1/16 scale "narrow" tire. I ordered a set of both the "narrow" and the "wide", to see how they looked - since the specs on them are sketchy at best. There's only a 1-2 mm difference in width between the two sets, not enough to justify the extra $5 per pair of tires. In addition to the minimal difference in width, they need different wheel profiles. The "narrow" tire needs a 39 mm OD on both sides for the wheel profile. The "wide" tire needs 39 mm on one side, and 40 mm on the other side - go figure.

Don

[Zabco]

I really like what you have come up with, they really look good. Even a drain plug in the rear cover. I had the same issue with multi-piece wheels and hubs when I was designing the dayton style wheels for my Mack. I'm going the make them just like the originals I thought. Well I'm blind in one eye and can't see with the other and yea, trying to get everything lined up and those damned little screws in is a real pain.

[frizzen]

Those parts are looking great! Sounds like the different versions have all lead up to some pretty nice axles. Wheels and diff covers look sweet

It's pretty bad when the model parts need to have a setscrew as a stud, or use a paperclip as drift punch just to align everything

[ddmckee54]

Last night I worked on the rear wheels, got the design done and started it printing before I went to bed. I think it looks pretty good, but it's got two major boo-boos and one "that just doesn't look right" issue.

Major problem #1 was the depth of the pockets. I pocket the wheel openings and the screw holes at the same time, and must not have been paying that much attention to the actual depth. The wheel openings were a little shallow but still OK, but the screw holes were only 1-2 mm deep.

Major problem #2 was that the 12 mm hex driver didn't fit, it was too small. I have been using Simplify3D for years, but it seems to have an issue with internal pocket and bore dimensions. I scale the model in the slicer to 103%, this gives me a final print that is dimensionally accurate to the 3D model within a few hundredths of a mm, at least externally. Internal pockets and bores were always too small. I've found that if I manually scale the dimensions of the critical bores and pockets to 103% before I send the model to the slicer things work out much better. When I checked the model I had scaled every critical bore and pocket to 103%, except the pocket for the 12 mm driver - you just can't fix stupid sometimes. I'm beginning to wonder if S3D just offsets all the dimensions away from the core of the print when it scales? (Maybe there's an advanced setting that I haven't found yet to cover that?)

My just doesn't look right issue was there's too much gap between the tires. I had it at about 5 mm, which turns out to be too wide. I reduced that to about 2-3 mm, we'll see how that looks on the next print.

Speaking of the next print, I just aborted it. I noticed on the slicer print preview that there were only 2 perimeter walls between the screw hole and the bore for the locknut, there should have been room for 3-4 perimeter walls there. Turns out I had used the clearance diameter of the screw, instead of the minor diameter. At least the print had progressed far enough that I could check the fit of the 12 mm driver - fits like a glove. Oh well, fix model, re-slice, re-print.

Don

[Zabco]

All educational opportunities, best way of learning. Strange though the way your slicer is doing scaling. I use Cura or PrusaSlicer, which is forked from slic3r, depending on which printer I am going to use and have never had that issue. When I size a cavity in one of my designs that's pretty much exactly what I get in the final print.

[ddmckee54]

OK, progress has been made - but it's been a LOT like doing the Hokey-Pokey. This is my current progress:
https://lh3.googleusercontent.com/pw/AP1GczNB5Gh7EgAq3-sbXeHWjGbbAnxLRFftfXA5E8nANqOgi4swSxEfdCGzPq68ofKa MCSTBW5tNlL95X1EPD5EJ_-mVc5WlKSl28t9l5oGkOsaYFU_6k58Wl7z9cskG8HSAPwm5G2RE 3v5UH_iZjfwisTh=w640-h480-s-no?authuser=0

From right to left we have the following:
1 - This is the cover for the locknut, The screws that hold this on will simulate the lug-nuts.
2 - This is the first version of the duals as described in Post #22. It didn't fit!
3 - This is the version that attempted to fix the issues from Post #22, it mostly worked. I tweaked the bores in the 3D CAD model by hand and realized this will be a royal PITA on a more complicated model - more on this later.
4 - This is my better idea, it ALMOST worked - more on this later also.
5 - Which you can't see, is bolted onto the other end of the axle and fixes the problem with #4.

This is the later. A couple of days ago I started a thread on another forum about slicer issues - with internal bores and pockets not being dimensionally accurate when scaled, here's the link:https://www.homemodelenginemachinist.com/threads/slicer-scaling-issues.36499/

I use Simplify3D for my slicer and I have always had to oversize the holes if I wanted things to fit together. It sounds like Cura has the same problem. I know from the diff housings that when I use S3D to scale the model to 103%, the external dimensions are within 1/4mm of the 120mm desired width of the housing - which is close enough. All of the internal bores and pockets measured too small though. The really confusing thing was that they were all too small by about same amount. They were all about 97% of the desired size. I got to wondering how the slicer was handling the internal bores and pockets when scaling, and if this was the problem with undersized holes all along. So, like Ford, I had a better idea. I took the task of scaling the part oversize, to allow for shrinkage, away from the slicer and gave it to the CAD program - which I reasoned was better equipped to handle the task. I reset the bores and pockets to their original values and scaled the part to 103% before I exported it to the STL file. #4 is the result, and it almost worked. Remember Major problem #2 from the above post? Yup, I do-ded it again. I didn't allow for any clearance Clarence! The 12mm hex driver would have been a press fit, and that's not good. I fixed the clearance issue and that resulted in #5.

Having wheels on both sides does tell me that I need to go back to the drawing board though. I currently measure about 200mm across the wheels and axle, I need to be at about 185mm. Now the question is where can I lose that 7.5mm on each side?

I added this image, to show that #5 exists and to show the gap between the duals. I think the gap looks about right. But I could shave a couple mm out of the gap, it's about 4mm-ish now. I could easily modify the wheel offsets 5mm and it wouldn't be too noticeable. I've got 100mm between the wheels now and the Bruder frame rails are 80mm outside to outside, so that leaves me a 10mm gap between the tires and the frame rail. If I move the wheels in 5mm that still leaves a 5mm gap, which should be enough for spring shackles and other odds and ends. I'll also have to move the angled transitions on the axle housings in 5mm, to give me a place to mount the springs, but that I'll fix when I re-do the pocket dimensions for the scaling fix.
https://lh3.googleusercontent.com/pw/AP1GczM10VUtsLUbYu7606mdJzZ1qquWGOxyLRlj1lKGB2vDrG O-0Mdli2kPJfeG0Ro2pmENa7MCHBa0QyCFYfUCYo17OdJBjDIV-l8TObi-E5vmGxfvltgtZLn1JNCVv0W4xmP0grOvLhTPycQb5uVCqEAh=w 640-h480-s-no?authuser=0

[ddmckee54]

Progress HAS been made! This is a family photo of the gang - so far.
https://lh3.googleusercontent.com/pw/AP1GczOYJSnDm90k0xftV7gOXrhCVh2rmjx90F6fG4qn6EhRcG 6-xGfSB5hCCoosuJAiD_YsOKxMKPIZeZI7MeWxUW2IcsPiYx9ehj yLXWTpwIM_F5fSbm-3KnZDGTCHN5Hp5QRBSi25a_VvxjlQ8RROdRbe=w640-h480-s-no?authuser=0

From back to front on the left side are:
1) The Kong axle with the modified rear wheels. I got my order of tires, so I can actually put tires on everything now.
2) The modified Frankendiff, still haven't shortened the axles though.
3) The prototype of the front axle - it still needs work. It's only got one wheel mounted because I don't have any more 5x9x3mm ball bearings. They are on order, should be here this week?
4) The other front wheel, with hub cover just laying in place.

On the right side are the next donor diff, and the left-overs from the donor front axle.

I've redesigned the rear axle's front and rear halves, making some minor tweaks.
1) I moved all the case mounting screw locations away from the axle bore, They were close enough to the bore that when the screws were threaded in, the inner wall would expand into the axle bore and bind on the axle.
2) I changed the angled transition to allow a convenient spot to bolt the springs to the axle.
3) I took the donor diff apart to see if the binding that I feel was coming from the spider gears - it was/is. There's no clearance in the gears. In fact if the screws that hold the spider gears cover in place are tightened down you can completely lock-up the differential. When I shorten the axles I'll take a little off the back side of the gears. That should make things work a little better.

The front axle needs a little help yet - it's 10mm too narrow. When I initially designed the front axle the plan was to use the steering arms, spindles and king-pins from the donor axle, which measured 205mm outside to outside. I need 175mm-ish, so I had to take 30mm out of the axle. The donor axle had spring perches that are spaced 80mm apart, which is right where I need them, but I need to lose 30mm somewhere. So I played with the design a while. This looked kinda OK on screen, so I printed it out. When I started to install the spindle assembly into the axle the spindle would flop around in the steering arm, they allowed PLENTY of clearance in this one Clarence! So, I am NOT going to use the original steering arms. While designing the new arms I came up with the idea of changing the front wheel offset by 5mm, to tuck the steering knuckle into the back of the wheel - so I did that too. And that my friends is why the front axle is 10mm too narrow. It's a simple fix and the axle only takes about 1/2 hour to print - just forgot about re-printing it.

Unfortunately the "Bag of Misfit Parts" continues to grow.

Don

[ddmckee54]

My 5mm ball bearing order arrived, so I put both front wheels on the axle. Here's a shot that shows a comparison of the overall widths of the axles.
https://lh3.googleusercontent.com/pw/AP1GczO7pL2egUxbKT08nZsofw-QpLlF6Xpuv6hQ7Pbx29vVpeFhncxuJEbL_eL8zq6rj-8vzidVbOdMGkAYHpGktQQuK32Oeyn92jvJuQC9xTvWElU8jaDu MZ6CofsAwNI26Mmibcpf8-2NSg983Gv2r_F_=w640-h480-s-no?authuser=0

Well.... The rear axle is pretty close, and there's less than 1mm difference between my red axle and the silver Kong axle. But the front axle - not so much, the front axle didn't work exactly as planned. You know the old joke about cutting something off twice and it's still too short? Well, I printed the axle twice and IT'S still too short! Only this time I don't think that it's all my fault. I noticed that the display on my 8" caliper will periodically jump 5-10mm. All of the outside to outside measurements on the wheels are over 150mm, so I've got to use the 8" caliper. It's a Harbor Freight special, so we'll see how good the lifetime warrantee actually is.

Here's a shot that shows the size of the Lesu tires compared to the Bruder tires.
https://lh3.googleusercontent.com/pw/AP1GczPSEGowOTszLzgZyg1ZrfqFSRgo07Inrs4lYMWeS_NB-H0g0adoqRu4SR6BGJSdPnlIHXAKw0Dzx8BOBswYb9i8AH54Vc4 9_2rH4dV9CB5Wg3w_RUqMy8LolRuZNimH2Y0xwtQNbRf7EZWGX AEitAyQ=w640-h480-s-no?authuser=0

This will probably be the first conversion victim. This will be one of the simplest, as in addition to forward/reverse and left/right, it will only require the drum to turn.(And maybe lights?)

Don

[frizzen]

I thought the "Bag of Misfit Parts' were to go with the "ghosts of projects future". Todays project doesn't need a 'Dr Seuss differential' with 7 pinions and 3 wheels, but who knows what might later? Or strap the bad parts to some pallets, now it's cargo.

Those axles & wheels are looking nice! Those seem to be a great fit on the bruder

That sucks about the measurements! The dial-calipers from Harbor are pretty solid. I've never messed with their digital calipers, because i don't really even care for digitals from good brands that are in a calibration program.

[ddmckee54]

I don't use the calipers for any critical measurements. Harbor Freight WOULD have replaced them, but nobody within 100 miles had any 8" calipers to replace them.

I tried using a spline in Alibre to get the curve I wanted on the front axle ends. I found out that they can behave unpredictably when you modify parameters, at least the way I used it they can. It would be nice if somebody would actually WRITE a user's manual.

[Zabco]

It doesn't always pay to buy cheap. I bought a Starret digital caliper for about $100 thirty odd years ago. Big money at the time. Other than having to replace the battery a couple of times it has worked great and is my go to for precise measurements. I have other measuring tools including analog and digital micrometers but the Starret is what I keep using. Was money well spent.

[ddmckee54]

I love the little 4" caliper that I got at HF years ago, but I think I just got lucky with it. I need a caliper that I can trust for a reliable measurement over 4", so I bought an 8" Mitutoyo last night.

[Zabco]

Yea, Mitutoyo makes very good measuring tools. I've got one of their digital micrometers. Dang thing will read down to like 0.00001 inch. Does like it's batteries though, always try to remember to remove battery if I'm not going to be using it for awhile.

[ddmckee54]

My digital angle gage is hard on batteries too, and it goes through three 2032's at one time.

I'm waiting on more parts to arrive, I was looking for a replacement pinion so I could build my center axle. Turns out the only way I could find the pinion was either as part of the replacement differential assembly, or as a complete rear axle. This diff assembly was only a couple of bucks less than the entire rear axle, and didn't even include any bearings. So I ordered enough rear axles to be able to do the next truck too. I've got some square aluminum tubing coming that I'll split and use for the frame rails, also got enough of it for the next truck.

While I'm waiting, I'll start on the rear suspension. I plan on making something like a Hendrickson Walking Beam suspension. I downloaded their tech manual last night and it's got enough illustrations that I've got a pretty good handle on how things are supposed to go together.

I do know that I'll need to make a couple of minor modifications to my axle housings, to give me locations to mount the axle brackets for the equalizer beam mounts, and the torque rod mount.

Don

[Zabco]

Don - sent you a private message.

[ddmckee54]

For the last couple of days I've been playing with assemblies in Alibre. So far I'm batting 1000, I've managed to break every one of them that I've tried - but I'm learning from my mistakes. That doesn't mean I'm making less mistakes, it just means that when they happen now they are WAY more impressive. This is my latest test assembly, I'm still trying to figure out how to save the current view.
https://lh3.googleusercontent.com/pw/AP1GczOw2CPvJw-TCyc80uh3OZQOwX1lrzbEB1twQFlSIkAwd7nW1KDgWWlp0MOeW HQ_1KtarX8Uu24C-SA4znwrc_A4oFUIpc658R7SxFE46mZRrq3HEe6BwD7f1pIYeMM DLhPeKPPCR4n83m2Btphsy5ig=w640-h333-s-no?authuser=0
I hope I didn't screw up the previous posts, when I previewed my post I noticed that I hadn't scaled the image for posting. Somehow instead of deleting just the unscaled image, I managed to delete the entire Frankendiff album. I put it back, reloaded the photos, and shared it again - hopefully all is well. Where's the EASY button when you really need it?

Now all I've got to do is figure out how to get my spring hangers, springs, and equalizer beam center pivot to fit into a 32x65x10mm volume.

Don

[Zabco]

Assemblies in Alibre can be one of the more frustrating things to do in that program. If two parts are off by only the smallest fraction of an angle, they won't go together. If two holes are out of alignment by as much as half the thickness of the hair on fly's ***, they cant be made concentric. Absolutely no more than three constraints on any component. Always anchor one of the first components you add, otherwise you chase components all over the screen. You can add constraints between components and planes or axis lines as well as other components. With constructions that have a lot of components make small sub-assemblies and then assemble the sub-assemblies. Sometimes you just have to try a number of different constraint configurations to find one that works.

The real nice feature of assemblies is that you can edit individual parts, or create new parts, from within the assembly. For example in the assembly you posted, if you want to add a cross member to your frame you can create the cross member, put it in position where you want it and then edit the frame rail to put the mounting holes to match the location of the holes in the new cross member. When you save the assembly the cross member will be saved as a new part file and the frame file will be updated with the new holes. FM

Have fun.

[ddmckee54]

Zabco:

I found about the sub-assemblies after about the 2nd or 3rd time my suspension assembly tried self-destructing the axle on me. I tried to pivot the axle around the equalizer beam pivot, and just about every part of the rear axle moved separately - and I couldn't undo it. The rear axle, the center axle, the equalizer beams, and the torque rods are all separate sub-assemblies now. I did discover that when you insert sub-assemblies they are rigid until you tell them to be flexible. It took me a while to find out why the axle beam mount brackets would pivot in the equalizer beam assembly, but when that sub-assembly was inserted into another assembly they wouldn't pivot.

This frame is just a test jig so I haven't made it a sub-assembly. It will be a sub-assembly when I start working on the actual frame though. The frame rails shown are sized to the 1-1/4" square aluminum tubing with 0.063 walls that I got. The rails and the cross-member are the only parts that are currently anchored.

I've been poking and prodding at my current suspension assembly so much that I've gotten it completely confused. I think I am going to throw this version away and start fresh - and LEARN from my mistakes, instead of repeating them. That's tonight's task, now I've got to finish the yard work.

Don

[Zabco]

All educational opportunities. What I love about all this. Keeps my brain functioning.

[ddmckee54]

I've given up on making a functional suspension assembly - at least for now. It seems like every time I add another part to the assembly, and try to constrain that part, it breaks a half a dozen other constraints. For now I'm just going to use the assembly to provide feedback for the design of the beam pivots, springs, and spring hangers. I already found out that I'll need to make spacers for my torque rods, to get them to the correct length. My torque rods are a pair of M3 ball links that are screwed together with M3 threaded rod, and a 1/16" spacer between them.

I know that when the axles articulate, things are going to want to twist around. That's why they use the rubber bushings on the real deal. I've been wondering how I could easily duplicate that. I first thought of using silicon fuel tubing, but quickly scratched that idea - the tubing was too thick. My current plan is to use O-rings with a 1mm cross section, on both sides of the equalizer beam. I'll use a piece of brass tubing as a bushing. The bushing will also keep the threads of the mounting bolts from cutting into the plastic parts or the O-rings. If I oversize the 3 bores in the equalizer beam, that'll give it a little room to wiggle around when the axle articulates - I think.

I guess the proof will be in the building.

Don

[frizzen]

If the Oring idea doesn't work out, you might be able to build up something like a bushing with Heatshrink tubing.

[ddmckee54]

Progress is being made, even if I don't have any pretty pictures to prove it. (I forgot to get a snapshot of the suspension assembly before I called it a day.) I will try to update the assembly drawing tomorrow, there's a bunch of stuff that's been added. I've added the cross-member that supports the frame end of the torque rods. I even edited the cross-member to put the holes for the torque rod bracket mounting bolts in the right spots. I've added the torque rods, the torque rod brackets on both the axles and the cross-member. I've added the spring hangers, springs, and spring perches - though they've only been added to one side so far.

I've kinda figured out how I'm going to make the leaf springs. The current plan is to sacrifice the tines from an old lawn broom to make the spring leaves. The tines are about 5mm wide and 0.5mm thick. The SEEM pretty flexible, but they still may be entirely too stiff.

I'm debating whether I want to try making U-bolts for the springs or not. I've got a bunch of bike spokes left over from re-lacing a couple of 20" bike wheels for another project. That would give me plenty of raw stock for making the U-bolts. For a limited production run like this, 3D printed forming dies will be up to the task.

Don

[ddmckee54]

OK, as promised we'll open up the picture page. (Who besides me still remembers the jingle for Picture Pages?)
https://lh3.googleusercontent.com/pw/AP1GczPeY2W47tC0e4ie9x0to_FhHB9N1mqUY0HssRXtB57Aff Oi7rFdQLxVcfdaAw4EGFMiQY1nHYxJGZJoER4YPTY3toawr1y1 eWKUkshkF5pQNHloJAPVdkxLB7xx_laW__lg2ZoSMHTHSo2b2C keXYEv=w640-h355-s-no?authuser=0
What you're looking at is the view from the passenger side, standing in front of the center axle looking to the rear.

I've temporarily hidden the passenger side frame rail, and just about every part of the suspension is in place now. I don't know how many leaves I will need for support, that's why there's a gap between the springs and the equalizer beam pivot bracket. I've got the springs drawn as three 0.5mm thick leaves, that may, or may not be overkill. I'll adjust the amount of leaves to suit the load, for now I'll probably just make a spacer block.

I'm still waiting for the donor axle order, according to the tracking it should be here within the next week. I sounds like the O-rings, the brass tubing, my 8" caliper, and the other odds and ends that I ordered should all get here about the same time.

Don

[Zabco]

Cool ideas, will be very interesting to see how they work out.

[ddmckee54]

I had a brain fart a little while ago, I came up with a way to bend 2mm U-bolts for the springs using 3D printed dies. Right now it's just a paper sketch. Tomorrow, I'll get it in CAD and print the dies out to see if my idea will work.

Don

[Zabco]

Several years ago I made some benders out of steel to make various types of u-bolts. Was a lot of work to make them. Squared, round, different lengths, different rod sizes, etc. I will be very curious to see how printed dies work out. May have wasted a lot of time.

Don't forget, you have to thread the ends of the rods BEFORE you bend them. Can probably guess how I learned that one.

[ddmckee54]

Well, the first attempt was an outstanding failure, which was not unexpected. It produced a rounded, sorta U-shaped object - whose legs were within a millimeter of being equal. However, I was TRYING to produce a squared off U-bolt with corners of a much tighter radius.

It was a bad die design on my part. I was afraid my movable die would allow the 2mm rod to move around.... It took the easy way out and moved. I didn't have nearly enough perimeter walls or infill either, 3 top layers, 3 bottom layers, 3 perimeter walls, and 30% infill didn't cut the mustard.

I'll double all of those on the next test, I'll also change the design of the top die. I want to restrict the rod so that it can't flex away from the top die like it did on the first test. According to the slicer, doing that will increase the print time for the dies by about 50%. Which will make it about 1-1/2 hours to print, and that's still not bad at all.

I'm only using PLA for the dies. If it doesn't look like that can take the stress, I can easily see modifications to the dies to allow the high-stress parts to be made of steel. (Or at least put steel in the high stress areas.)
Don

[ddmckee54]

OK, the second verse is ALMOST a repeat of the first, and I've got pictures to prove it.

This is the parts of the first die.
https://lh3.googleusercontent.com/pw/AP1GczO4EC5helFeEG1Q9NyCjzZblqTWV035CrzOKg34ONqk9g 1Z1m1D59NoDLduUNhBU0TNbOn120075A6iF8NDTUfKCZC0dKmo 6dVQh3fYQbkk18qXPkaADR4NvdQvBU7tyMkHCYk6y1dsiMNyIf JoyiJV=w640-h480-s-no?authuser=0
The movable top die is on the left and the base die is on the right. That V-for-victory shaped thing in the middle is the result of the first pressing - IT won. I'm using a Harbor Freight 1/2 ton arbor press to do all the pressing.

This just shows how things went together for the first press.
https://lh3.googleusercontent.com/pw/AP1GczOTIgs2rw_eFsANCmMl4VmnnZt-hEoQao-6EuefiSugg7OdMrROLZPT0KAY8iPTLqu9xwW9Fd4GSZDhADStl OsY5bo6FR-b9zVgH4lpZHBxr3Ta6cPApFHWPuJejNV-tILtzGkNmCuwMhSSm5ywkAEs=w640-h480-s-no?authuser=0

I modified the base die and the top die for the second attempt. The first dies only had 3 bottom layers, 3 top layers, 3 perimeter walls, and 30% infill - I doubled all of those for the second attempt. The areas that had the most damage on the first dies were where the 2mm rod contacted them as the rod was being forced into a staple shape. The bottom of the top die took a real beating, but the radii at the top of the U-bolt slot in the base die also took a hit. I can't get a decent close-up picture of those areas so you're just gonna have to trust me on that one. Other than upping the wall count and infill, I couldn't think of an easy way to beef up the top die. The bottom die on the other hand was easy. I used steel, in the form of a pair of 1/4"-20 bolts. I punched a pair of holes through the base die, so that the outside of the bolt's shank replaced the radius in the slot for the U-bolt.

This is the parts of the second die, and the results of the second press.
https://lh3.googleusercontent.com/pw/AP1GczMZhncrbod9egIvNvbt0sDZVJ0XSxI-SFecIgCdeIqxifSYueX8flW_TciCeFzw3OOQMGySc7WgPJrKgF G34HUbEGlgT9mZP642yDPuikoEGWPqaTNAPRg32atGhsNWjv8b Oo14LPAoh84lTulX8cgQ=w480-h360-s-no?authuser=0

I have the beginning of a squared off U-bolt going on there. The top die still took a beating, but not nearly as bad as the first time. If I make the top die out of steel I should be just about there. It's a simple piece of 5mm flat stock with a 2mm slot cut part of the way across it - eazee-peasee.

The is the second die set up to press.
https://lh3.googleusercontent.com/pw/AP1GczPSUOBTm0i0yZXJxNKW1b2Z-v181gnp76zf8jDyqAEKPZu7wls8bowmkl_aWYYpsgBRW0MXEtR 4b2MQkUFRc6CamSKy0OcXgPqqkIyuvGGPbYxIzMRUXf9c0X1GN 5ASJ2WVp2H03OcMhuWS2H8PJTmT=w480-h360-s-no?authuser=0

Don

[ddmckee54]

Well, my shipment of donor axles failed to arrive. Apparently the US Postal Service lost my order, they were the last to touch it on October 29th - after that the order apparently disappeared into La-La land. I got a refund on that order and placed another order, this time from a US shipper. That order is supposed to get here Friday.

I did re-make the top die for the U-bolt bending contraption, milled it out of a chunk of 1/4"x3/4" hot-rolled flat stock that I had laying around. There was some improvement, but not as much as I would have liked. However, squeezing the legs of the U-bolt while it's still in the top die closes things up nicely. I haven't threaded the legs of the U-bolt yet, I've just been trying to get as close to a 90 degree bend as I can. Now I'm thinking that the way I'm forming the legs of the U-bolt will just smear those little M2 threads out of existence. I think if I slip some brass tubing over the threaded sections before I bend the legs, that should keep the M2 threads for being destroyed. I'll need to modify the lower die to accommodate the tubing though.

My order of 6mm OD O-rings arrived yesterday. Those are for the equalizer beam pivot brackets, to allow things to flex a little. I don't think I've ever received a package that was as well protected as that one was. The O-rings, all 100 of the little suckers, were in a small zip-lock bag. This bag, and a thank you for your order note, were then put in a slightly larger zip-lock bag and wrapped in a double layer of bubble-wrap. All of the above was stuffed into a bubble-wrap lined shipping envelope, which the US Postal Service actually delivered to me this time.

Since I had to modify both the front and rear differential housings, to give me a fixed location for the equalizer beam and torque rod pivot brackets, I need to re-print the diff housings. Soooo... I might as well change the filament in the plastic-pooping-robot over to black. That way I "shouldn't" have to paint the suspension parts black. I might as well print out enough parts for both axles while I'm at it.

Don

[frizzen]

For the shackle benders, what about designing to use some needle-bearing rollers as the radius for your hard corners? Or even trying embedded needles in a Hotrolled version

[Blender]

Pretty hardcore to make your own ubolts. Getting pretty close now. I would think having the threads formed first might be easier. A M2 die may not fit once the legs are bent.

[ddmckee54]

The 1/4-20 bolts that go through the bottom die form the outside of the U-bolt legs. I just counter-sunk the end of the slot in the top die and that helps to form the inner radius of the U-bolt legs. I have to cut the threads first, there only a little over 5mm between the legs of the U-bolt. While I have no doubt that there are people out there who can make and harden their own custom M2 dies that would fit in that 5mm slot, I ain't among them.

I ordered some 2mm ID brass tubing to protect the M2 threads while bending the legs, I have no local source for something like that. What did we do before on-line ordering? Don't answer that, I'm old enough to remember what we did back in the the "Old" days.

I re-made the top-die for the U=bolt bending contraption, I milled it out of a piece of 1/4"x3/4" hot rolled flat stock I had laying around. In the process of milling the top die I've discovered how poorly I've got things organized in my shop, and how badly I've neglected my little lathes/mills, I've got a Unimat SL that I purchased in 1973 from my local Sears catalog store. (Hold up your hand if you actually remember what a catalog store was, or even a paper catalog for that matter.) I've been collecting tooling over the years, but not that much experience. About 5-10 years ago I had the chance to purchase a Sherline 4000 and a BUTT-LOAD of tooling from a gentleman who was down-sizing his shop, it's mostly been sitting in a box since then. That has all changed in the last couple of weeks, they are now getting the TLC and attention that they deserve.

Don

[Zabco]

Oh wow, cool. I have a Unimat SL also. Was the first power tool I ever bought. Bought mine a couple of years before you and got it through Montgomery Wards (remember them?). Was right around $200 if I remember correctly. Heck of a lot of money back then for a kid in high school. Also learned real quick that as a rule of thumb however much the machine costs, you need to spend at least that much more to get tooling you need to use it. I also have a Sherline mill and lathe both equipped for CNC. Only used it on lathe once but use on mill quite often. Today I primarily just use the Unimat as a drill press for tiny holes. Love that little machine, carried it with me all over the country.

I have made several u-bolt benders similar to what you are now doing and damaging the threads was never really a problem. Didn't have an arbor press to push the plunger into the die so used to use a bmfh. This often led to bent/broken plungers. The biggest issue I had was getting the legs of the u-bolt to end up the same length. Today I make up/use benders that hold one leg in position and then bend the bolt around a pivot of the size needed.

[ddmckee54]

Zabco:

Yeah, I remember Monkey Wards. Now that you mention it, it might have been a Wards catalog store. I know a couple years later when I bought my stick welder and my band saw, THEY came from Sears - also the store was in a different town. That little Unimat has survived 8-10 moves over the years. I don't like the round column on the Unimat, but I DO like having the quill for drilling.

I'm thinking it might not be a bad idea to cut and thread the legs of the U-bolts extra long. I can always even them up later.

[Zabco]

Growing up as a kid I always loved to go through the hardware department of Sears stores. Didn't really know anything about machine tools and the saws and drill presses and lathes in Sears always fascinated me. Then I bought my first table saw from Sears and learned why their prices were lower than everyone else. Couldn't keep that thing in alignment for anything. Got rid of it in a moving sale and started going to real machine tool dealers. Their basic hand tools were ok, I still have my first set of sockets and wrenches from them, but power tools, uh-uh. Now Lowes sells the Craftsman name tools and I won't even look at them.

Good idea with the u-bolts, I had never thought of that. Considered how to make the 'squared' u-bolts?

[ddmckee54]

A squared off U-bolt is what I'm aiming for. But.... that's gonna be on hold - at least for a little while.

Meanwhile I'm going to nominate myself for Bone-head of the Week-Month-Year. (Take your pick.)

Last night, while working on a more permanent base to mount the Sherline onto, I managed to drop the dang thing. Not the base, I managed to knock the Sherline off the bench. Although the base wound up on the floor too, when I made a grab for the lathe. It, the lathe, bounced off a cabinet and a shelf on the way down and tried to spear the concrete floor. That concrete has been hardening for over 125 years, it barely even got scratched.

The headstock end of the lathe took a hit though. I tore the lathe bed apart and there appears to be only one casualty. I mentioned that I had purchased the lathe and tooling from another gentleman several years ago when he sold the whole kit-n-kaboodle to me. He bought most of the extra doo-dads that Sherline sold for the lathe, among them was the manual threading attachment. This attachment lets you do single point threading on the Sherline. The dog that engages/disengages the lead screw from the change gears is what took the hit.

Since the only time that is needed is when you're threading, and it will be MANY-MANY moons before I'm ready to jump down that rabbit hole - I'm just going to take it off for now. I'll just add it to the other busted parts in the "Box of Shame".

I've looked on the Sherline parts web-site, and it looks like that particular part is no longer available. It's beginning to look like when the single point threading time does come, I'm going to have to make a repair part before it can ever happen.

Meanwhile, now that I've got the lathe bed torn completely off, I'll clean the gunk off the spots I couldn't get to previously. Then MAYBE I'll be able to get back to where I was 4-5 hours ago - before the boo-boo.

Don

[Blender]

Sherline lathe is my most used tool by far. My matching mill is CNC but I don't use it as much. CNC quickly became a hobby within a hobby. I just want the parts. Super exciting to see you've busted out the lathe. I had a harbor freight 7x10 or whatever and hated it. Sure it could take a heavier cut, but I could never get the tailstock aligned well, nor the bed and head just right. The sherline is a workhorse as long as the cuts are gentle.

I mounted the lathe to a big chunk of aluminum rectangular tube. I think it's around 2" x8" x whatever length with 0.25" wall thickness. Found it in the scrap section of tye local metal shop. Lets me tuck some wires in the hollow and mount a DRO. Rubber feet on the bottom. Love that machine.

[Zabco]

Oh man, reading that made my head hurt. I'm really glad the damage was not any worse than that. Find it hard though to think that Sherline can't provide a replacement part. I have the threading attachment also and while I don't use it a lot I do use it. Biggest issue with it is just figuring out which gears I need and the order to install them. If you do start to do threading, piece of advice. Always remember to back out the cutter before returning it to the start of the next pass. Especially if using a carbide cutter. I've broken off way too many cutter tips because I can't remember to do that.

[ddmckee54]

Blender - Almost 50 years ago my first job was in maintenance in a plant that made plastic laminates of various types and thicknesses. I got some of the reject pieces before I left. I'm using a piece about 1-1/8" thick for the base. It's straight, heavy, and resistant to oil. The base for the Unimat is similar, but its' core is canvas instead of kraft paper.

Zabco - While I was looking on the Sherline web-site for repair parts last night I did see a calculator/spreadsheet that will give you the gears to use. I couldn't get it to work, it gives me a lot of #REF errors, but that could be because I'm running Open Office on this PC and not Excel.

After doing a couple of last minute outdoor jobs, like making sure the snow blower actually runs before I REALLY need it, I decided to take another look at the carnage from last night.

I've still got the one casualty, but it's not a fatality like I originally feared. I was able to thread a screw into one of the parts that were jammed together, and then clamped the head of the screw into my vise. A piece of wood, a smallish BFH, and a little judicious tapping later and they were apart. There were several non-factory burrs and dings that needed to be dealt with. The only downer now is that the drive pin that keys the gear to the shaft driving the lead screw is MIA. But that looks to be a piece of 3/32" rod, so replacing it is no biggie.

I'm still not quite back to where I was last night, pre-fall, but everything is moving much better than before.

I know Sherline says to use light oil to lube things, but right now all I've got other than 5W-30 is 3-in-1 oil - what do you guys use?

Don

[ddmckee54]

Well, I got some parts today, my axle order arrived and I got the 2mm ID tubing I ordered.

Not my first order of axles, this was the second batch that I ordered. Surprisingly, or maybe it wasn't really THAT much of a surprise, all 6 of then feel very crunchy when I try to turn them. I had hoped that this lot might at least turn right out of the bag. I suspect that I'll find no clearance in the spider gears.

You remember how impressed I was with the care taken to protect the O-rings? Well, let's just say the shipping for the tubing is on the other end of the spectrum. They were shipped in a zip-lock bag inside a non-padded shipping envelope. And not even a heavy duty zip-lock bag like the O-rings had. The shipping bag looks it's gone several round in a fight that was above its' weight class. There's 6 or more holes through the shipping envelope, but only 1 of those is anywhere close to where the tubing ends were. But there's no holes in the zip-lock bag, so whatever chewed those holes in the shipping envelope was on the outside trying to chew its' way in. Not on the inside trying to chew its' way out to make a break for it. All the tubing has a slight kink to it, but I only need short pieces so I'll just avoid the bends.

Don

[Blender]

1.125" plastic slab sounds like a great lathe base.

That's a relief the lathe isn't as far gone as feared. I use 3N1 oil since I usually have it on hand as an "indoor" oil.

[Zabco]

Really glad to hear that the damage is not as bad as feared and that you will be able to get it fixed.

I have the tables that Sherline has for both imperial and metric threads for their lathes, it's just that I always have to look up the instructions as to where A gear goes and B gear goes, etc. BTW I would recommend that you ditch the Open Office program and replace it with Libre Office. Both are free and both started from the same source code. But Open Office is not being worked on and has not had an update in over 10 years. Libre office has an active group of workers constantly working on updates. I found that it works much better.

3 in 1 oil should work just fine. I use a gun oil just because I have it. Been using it for over 15 years with no problems.

I usually buy rod and tubing from either ksmetals.com or mcmaster.com depending on size and material. Probably not the cheapest sources but I have never had any kind of shipping issue with either one. My LHS does not keep up their stock of raw materials like they used to so I had to go to internet orders.

[ddmckee54]

I "WAS" going to print out a new lower die for the U-bolt bender, so I could try my idea of using the brass tubing to protect the threads when bending the legs. My printer had other ideas though, I got a plugged nozzle on the 2nd or 3rd layer.

I changed the nozzle and started another print, about half way through it jammed again. This time it took out the PTFE liner. This is the second time in about a month that I've had to change that liner, and I didn't have any more spares. I ordered some more liners, and some new nozzles, and they have arrived. I'm going to just pitch the remainder of that roll of filament, It was several years old anyway. I had something similar happen a few years ago, only that was a brand new spool. When I changed the filament all the problems went away.

I've used old filament before, usually with no problems. I normally store any left-over filament in a zip-lock bag, and I'll throw a couple of desiccant pouches in with the filament. I usually don't have any problems doing this. However I have noticed that if the filament is a year or two old or more - it does tend to break in the feed tube to the extruder. Especially towards the end of the roll. It won't break while printing, but if the printer sits for a couple of days there's apparently enough stresses built up in the filament to cause it to break.

Bottom line - the plugged nozzle, the bad PTFE liner, AND the rest of that roll of filament are going to be introduced to the trash can when I put in the new parts.

Don

[ddmckee54]

Christmas miracles do still happen - sorta.

Yesterday, 12/23/24, I received an odd shaped package in the mail, in it were 6 axles for WLToys 12428/12423 1/12 cars. I ordered these axles in mid September. A few days after the delivery window had ended I contacted the seller telling him that the order hadn't arrived. According to the tracking records it was delivered into the hands of the "Final mile" shipper in mid to late October - and hadn't moved since. The seller contacted the shipper requesting them to search for the package. About a week later, with no response from the shipper, I asked the seller to refund my money - which he did on 11/19/24.

Then yesterday the axles showed up, the package had been obviously opened and resealed. The package was tagged as inspected by US Customs. I contacted the seller and told him that the axles, for which he had already refunded $87.76 to me, had finally arrived. I told him that I had received the refund in mid-November and asked him to send me an invoice for the $87.76 that had been refunded. So that I could pay him for the axles.

Today I got an e-mail from the seller thanking me for my honesty. He also told me that they couldn't access the refund from their end, so I should just forget about the money and to have a nice Christmas.

Small Christmas miracles do still happen.

Don

[ddmckee54]

Been a while since I updated this thread. The original plan for the WLToys 12428 drive axles was to shorten each 5mm OD axle about 30 mm. Turn a 13mm length of each shortened axle to a 4mm OD, thread that to M4. and then cross drill for the drive pin. Then I started wondering if it wouldn't be easier to get heavy wall tubing, use it as a sleeve, and Loctite the shortened parts back together, that was the plan anyway.

Over a month ago I ordered some 5mm OD brass tubing with a 1mm wall thickness. Today the 3mm ID x 5mm OD tubing that I ordered finally arrived.

I've got my supply of donor axles, including a few spares. It was cheaper to just get a complete axle than to get just the additional pinion and bearings that I need to build the center axle. The Sherline's been modified by adding the remote digital readouts. I guess that now I need to find out how many axles I have to trash before I get a working drive axle set.

I'm blaming Blender for throwing me down the front drive axle rabbit hole. His use of the Losi front axle shafts in his current telehandler build is what got me scratching my head and going Hmmmmm... So I ordered the replacement front axle shafts for the 12428 to check if they would be usable. They also arrived today, and it looks like a front drive axle is do-able without too much trouble.

Don

[Blender]

:D If I am going to have unfinished projects, everyone must. Excited to see where this goes

[Zabco]

Thought they were all unfinished projects, mine are.

[ddmckee54]

Yesterday I cleaned all of the god-awful smelling factory grease off the donor axle parts. I need to make several modifications to the axle shafts and I don't want to be smelling that crap all the time.

I know I need to find some clearance for the spider gears, but how much do I need? I knew that if I backed off the screws holding the ring gear to the spider housing the diff worked as advertised, but how to measure it? My idea was to use the M2 screws that held the spider housing to the ring gear as my indicator. If I count the number of flats as I loosen each screw until I find the sweet spot, that will tell me how far I moved the screw. Turns out that sweet spot is 1-1/2 turns out from tight. An M2 thread has a 0.4mm pitch, so 1-1/2 turns means the head of the bolt moved 0.6mm. I need to take 0.3mm off the back side of the bevel gear on each axle shaft to make things fit right. I think that's right, gonna need to try it and find out.

I also need to shorten each axle by 29-30mm. I'm not sure if that number will be affected by my fix to the spider gear clearance problem. I don't think it will but I need to try it and find out before I start whacking chunks out of the axles.

[ddmckee54]

I cut the existing axles with a hacksaw and took 0.3mm off the backside of the diff gears on the axles. I haven't spliced the axles back together yet, but I reassembled the differential to see if I have gained enough clearance. The differential now works correctly when the differential cover screws are completely tight, but it works better in one direction than the other. It turns in both directions, but in one direction it is definitely harder to turn. I also noticed that there is no noticeable end-play in the axle shafts. There is no grease in the gears right now and it is entirely possible that with proper lubrication and a little run-in time this will clear up

I'm using the Kong axle that I purchased as my benchmark so I checked to see if it had any end-play in the axles - it does. So maybe I still need to take an extra 0.1mm off the back of the gears on the axles.

[ddmckee54]

WELLLLL... things did NOT go exactly to plan, the best laid plans of mice and men - and all that crap. My very first plan was to remove the gear from the end of the axle shaft, shorten that end, cut new flats on the axle to match the gear, and cut new threads to match the screw that holds, the gear on. The only problem with that plan was that I could not get the screw to break free, I even tried heating the screw to try get whatever thread locker they had used to break free. The only thing I managed to do was to round out the hex socket in the screw. The next plan WAS that I would cut the steel axles in two, turn a stub about 10mm long on the cut ends to a 3mm OD, cut a piece of 5mm OD x 3mm ID brass tube to use as a splice, then Loctite everything back together. Easee-Peezee, right?

Things did not go well from the beginning, then went downhill rapidly after that.
Problem 1 - How do I hold these little turds to cut them? My first thought was to use my metric ER16 collets. Something like this IS after-all why I bought them and the collet chucks for the Unimat and the Sherline. So I blissfully cut the axles apart with a hacksaw, figuring that I could easily clean up the ragged ends with the lathe. Heck I could even chamfer the ends, 'cause chamfers are what separate us from the savages - right?
Problem 2 - I knew that the collet chuck for my Unimat registered on the shoulder on the spindle nose, I ASSUMED that the collet chuck for the Sherline did something similar. Imagine my surprise when I opened the box to find that the collet chuck for the Sherline registered in the spindle taper, AND uses a 1/4" bolt as a drawbar to hold it in the spindle. OK, that means that if I need to work on a longer part I'll need to work on the end hanging out in the breeze, and not work next to the chuck where there's less flex. That actually worked fine on the ends that were threaded for the wheel attachment.
Problem 3 - The other two pieces of the original axles still have the gears FIRMLY attached to them, and I need to work on the OTHER end. NO Problemo, I'll just slide the gear into the spindle bore, the bore on the Sherline is HUGE compared to the Unimat. AAWWW CRAP, there's already a drawbar there. The gear fits inside the collet chuck, maybe there will be enough room to put the part in from the back - THEN tighten the collet down? Nope, there may be a mm or two of clearance there, but there's not ENOUGH mm's. OK, lets swap out to the 3 jaw. Then the gear can just slide into the spindle bore.
Problem 4 - I got out the 3 jaw, cleaned everything up, and installed it. It has been sitting in a box for years - remember? I opened up the jaws, slid that part in, and... IT DON'T FIT!!!! WHADDAYAMEAN, it don't fit? That bore is huge, it's 10mm, and the gear is only... 10.6mm. OH Crap!
Problem 5 - I can't work on the area of the shaft I want to - where I want to work on it. But, I've got a lot of the brass tubing, I can make the splice as long as I want. I can pull the part out until it bottoms out on the back of the 3 jaw, I want to eliminate that cross drilled hole if possible. Pulling the part to the back of the 3 jaw puts the existing cross drilled hole inside the sleeve, but not by much. But, it IS inside the sleeve, so MAYBE it'll be OK?
Problem 6 - I needed to turn a 3mm OD stub on the cut end of the axle - Easee-Peezee. I figured I'd take off 1.1mm then sneak up on it - no problem. So, I made several passes taking a few tenths of a mm at a time and didn't stop to measure until I hit 1.1mm of movement. WTF, whaddayamean 2.82mm OD?? I only took off 1.1mm, but I took it off of each side didn't I. I was much more careful on the second axle. That gap is way more gap than any of the Loctite that I have is good for, but I can always use JB Weld. So I did, This is what the axles looked like at this point.
https://lh3.googleusercontent.com/pw/AP1GczM81rr2XthYmVrALsWeGlw-fmWm8rWRvl-txjEiODAkxuGEkYL53opbqNeVpQQJN_Vkgi-ihPkE3_gRlHXUj4sDXb98i_LMddx85UmVMh-6AgHJgKwFjJl2w9C6YROrVTVfLlrIWYDEy1HMb5Wnhggc=w640-h480-s-no?authuser=0
Problem 7 - I needed to shorten the brass sleeve to length. Since the gear's OD is larger than the spindle bore I had a LOT of stick-out, about 25-30mm's worth. It did not end well.https://lh3.googleusercontent.com/pw/AP1GczPMkjRyYhle7g74zp2UhPqRM_z4xKsTpEkpjS32xhiJHy drb9JPeGNJm_XDtQQ0SbEjj8XnkcXVtQb_9hqJ3oIbqbkR7GEw lYG4jRKequp_XoOFkVenIwAY8AgQBP2QooeI3vwBitfoLnQ0qj eWObta=w640-h480-s-no?authuser=0
It snapped off right at the cross-drilled hole location. I think the axle would have been strong enough for the loads it will see, if only I would have just put the splice in a spot that's not close to an existing cross-drilled hole. I also found out that I need to make any axle shaft modifications starting on the outboard end, rather than the inboard end like I did this time.

The good news is that because I ordered complete extra axles, instead of just the extra pinion that I needed to make a center drive axle, I've already got spare axle shafts to work with. The extra bearings are the same size as what I would need for the front wheels if I decide to make a powered front axle.

Don

[Zabco]

Oh man, I feel your pain and aggravation. Morse taper and draw bolt is good when you want concentricity but a pain when you need length behind chuck. How were you cutting off the excess tube? Parting tool? I find that on my Sherline using their adapter to hold the parting tool cutter upside down on the back side works much better. I would really like to know how they installed those gears on the shafts. Sounded like you had a real good game plan.

[ddmckee54]

Zabco:

I was using the parting tool on the front side.

Regarding the gears, I'm seriously considering throwing the one remaining shortened shaft into the oven at 300 degrees F for 20 minutes. That SHOULD soften whatever type of schmoo they put in there, and still not destroy the die-cast gear. I need to be able to get that gear off if I want to make a serviceable powered front axle.

[ddmckee54]

After 10 minutes in the oven at 300 degrees F, and we have a winner.
https://lh3.googleusercontent.com/pw/AP1GczPM_3_rSOP9KHJpIbRrsRy7ktDjBUvzd972j50hgtXsDO gT18BrHcphvwT8YBMP0ZB8q_bY5tnIjaBr_yHt-C8drKbTUBr9KoMFZ0tN2EIpJsybCtWtKup_2r-yHkPWacc0FXaGjup6IJhQffp_UWAQ=w640-h480-s-no?authuser=0

Being able to do this should make things a little easier for Future Me.

[Zabco]

That's good to see. Little factoid to file away for future reference if I ever try to do the same.

I was using my cutoff tool in a QCTP for quite a while and always had issues with it. Given the thinness of the blade I even managed to shatter a couple. I read somewhere about changing to the upside down cutter from behind and gave it a try. How I've been doing it ever since.

[ddmckee54]

OK, there has been a little progress made.
https://lh3.googleusercontent.com/pw/AP1GczMtZO96EckZVmx23yUfn6olRW4xRskPrNYfGbvulcCeIf 4tKlo0Fsswk64uXNneDUrXSUdAb2otHfzHdK9fpvGMJi5eeHN8 BeSCOx1HcM5nk_JBAki445vyuMhtuMOXLqXDkL_mQvtoQlHbVh aNkrpP=w640-h480-s-no?authuser=0

I cut down the partial axle that was shown previously, and took a little more care with the diameter this time. I glued the turned stub into the brass tube using a Vee-block to align the parts as the Loctite cured. The original axle shafts were about 101.8mm, I rounded this up to 102mm. I had calculated that I needed to take 28mm out of each axle shaft. But I wanted this "practice" axle to be too long, so I added another 4mm onto my target length. I then cut the 5mm diameter end of the outboard axle stub to length and turned a 3mm OD stub 10mm long on that end. I then slipped the axle shaft together and checked the length with my trusty HF 4" caliper. After deciding it was good enough for "gubmint" work I glued the parts together, again using the Vee-block for alignment

After things had cured for a few hours I couldn't wait anymore and decided to test fit the axle in my 3D printed Frankendiff housing. I had added another 4mm onto my calculated axle length, and there's a 4mm gap between the 12mm hex driver and the outer bearing. So I've got a working procedure for narrowing my WLToys rear axles for use on my Bruder truck RC conversions.

Now I only have to do this at least 4 more times and I'll be able to get onto actually building the truck. I said at least 4, but it will probably be 6 times since I'm 99.44% sure that I'm gonna swipe Blender's idea and also build a powered steer axle.

Don

[Zabco]

Congrats on getting your process worked out. What I love about this hobby, educational opportunities just abound. Which Bruder are you going to convert first?

[ddmckee54]

Probably the MAN concrete mixer, I've already got it de-boxed and it's currently sitting on my table. The suspension parts have been designed around measurements taken from it. Although the other truck suspension parts measure close enough that I can use the Frankendiff on them too. I made sure it'd work back when I started this adventure.

That was the whole reason for this design exercise, design an appropriately sized differential for use on all my Bruder truck conversions. Educational experiences, I've been teaching myself how to use Alibre Design Pro at the same time.

[ddmckee54]

A little more progress has been made. I was able to find the broken stub that was shown in Post #68. I thought that I had pitched it, turns out I'd just misplaced it. I found it when I went to use the toaster oven to remove the gears from the next donor axle. I have enough bits and pieces that I now have the fixin's for 2 complete differentials, if I could get that M2 screw with the rounded out hex removed. While the toaster oven was hot I also took apart the axle shown in Post #73 that was 4mm too long. At some point over the last several years I had purchased the smallest Easy-Out I've ever seen. I was able to get enough purchase with it that I could back the screw out enough to grab on to it with a pair of pliers and remove it.

Today I modified the stub axles that I already had cut apart. The axle shaft from Post #73 was 74.27mm over-all in length, so I'm aiming for a 70.25mm length in my completed axles. I modified the first axle, Loctited it together, and left it clamped in the Vee-block while I modified the other axle.

One measures 70.14mm, and the other is 70.38mm. Not bad for a beginner, but I plan on doing better next time. And, the only thing that I had to scrap was that bent length of brass tubing shown in Post #68.

[ddmckee54]

Zabco:

I was using the parting tool and holder that I got with the Sherline. I was using it on the front, but it had to have a LOT of tool stick-out in order to get it on centerline. I have since switched to the 1.5mm x 6mm parting tool that I got for the Unimat, If I want to use it on the Unimat I'm probably going to have to get another one of them. I mounted it in the rocker tool-post I got with the Sherline, and that's where it will most likely stay. I put it on the back as you suggested, and things went much smoother. That could have been because there was less tool stick-out, but from now on parting off will probably be done like that.

I did have a problem when I tried to take off a 0.13mm cut like that though, it seemed like that 1.5mm blade just wanted to deflect. I got a BUTT-load of tooling with the Sherline, including a bunch of brazed carbide bits - most of them still had the wax coating on them. After trying one I understood why they were unused, straight from the factory the brazed carbide cutting edges are useless. The set I got from HF years ago were the same way, the bottom edge of the brazed carbide would hit the part before the "cutting" edge would touch the part. After touching up the relief angles on a diamond hone, so the cutting edge actually cuts instead of just rubbing the part, I have useable brazed carbide bits.

I've also got a complete prototype modified axle.
https://lh3.googleusercontent.com/pw/AP1GczOhPkTSIDmlHl0Dk8Sd2M0TQFGWurrNUcvvuZ3KS7KzLE ININEqpKlUmaVQi4Am_HWxPaV-EhJ1yvRcIORm5cQYdXBzj4zHsW1qgUYgCJLtKV85UkyI5FYbK1 aGmN8l9rt1UgZbGsUxVdQUfkkD4i4g=w640-h480-s-no?authuser=0

[Zabco]

Yea, with the Sherline parting tools you need to keep the blade as short as possible. Because they are so thin they can be easily deflected. And that of course will lead to problems. The other thing, if you aren't doing it, is Sherline recommends slowing your rpm speed to about half of what you used to turn the part and always use oil. I had not thought of using the Unimat cutter. I have one but would have to regrind it as I ground it to a curve to cut the grooves in a bunch of pulleys I had to make. Glad to hear its working for you. Your new axle looks real good, can't wait to see it in action.

[ddmckee54]

The axle looks good, but when I transferred the duals from the Kong axle onto my axle... the wheels sorta fell off the bus. When I tightened them down they wouldn't turn. I took things back apart and started measuring bits and pieces.

The 12mm hex driver from the Kong axles is 6.5mm thick and uses a drive pin with a 1.5mm OD. The WLToys hex driver is 5.5mm thick and uses a drive pin with a 1mm OD. I backed things off enough that the wheels turned freely and did a sanity check against the Bruder tires.

From this angle things look OK, however...
https://lh3.googleusercontent.com/pw/AP1GczO2pAbaLZac6J7zKdDv_00sHDSBNzUssLb4MkgEqI5Dz9 OjMgqO-ngLqEC3GBYBaL6H8tloci8p7aamV6qaqPX7Not2XtMpvS02GfL EILZFMd1Nuy1C2ljzm_WgzEFESbs2zOTBiQU89ED1YDGajGPQ= w640-h480-s-no?authuser=0
From this angle you can see they're too narrow by a couple of mm.
https://lh3.googleusercontent.com/pw/AP1GczM_BbFVC84_y74Ejnkvj2hz68jWT3Pp0WcwBjpKV7OQKd 5C-j-BGTF5zj2Lyj4Gd4CUl9dF36JtEo74e79sCV7gab9ogIBboBfUV VGznNYaGcsDvT71AcxAOVcrcMQu9M-QXzl1eFK6jAhSvEweDN1X=w640-h480-s-no?authuser=0
If I make the driver pockets 5.5mm deep instead of their current 6.5mm depth then things should be just about right. I think I'll make the pockets 5mm deep though, because a little clearance nerver hurts Clarance.

[ddmckee54]

It's been a while since I was able to update this thread. I reprinted the rear wheels fixing the hex pockets, it's shown here along with the donor axles that need to be modified for the center axle.
https://lh3.googleusercontent.com/pw/AP1GczO2QVAVYxVDnECumoY9koyb5Cb9e8xQLprytz28mofq0V YyZGTPRh35Wz0AmHeTdkExHtcZORzx3dKcoz6YwDKn49VaWGLV nnWYxvxbvyusHBygv3YVa5MqGKWIK4xCfmYp4dt-kuv_QuS1kh0DoVck=w640-h480-s-no?authuser=0
I finished modifying the second set of axles that will be used for the center axle, this is the modified axles.
https://lh3.googleusercontent.com/pw/AP1GczN5-Ke7M3XhCLYmczJpGKz2kXURkWQlANklcV4J7F_NN-_aluBnjQu4U09T2IBlcAQvFt7VFSfkQq5h-U0p7KBv4ZHPqnjBEx-puBLoBEzO1DJGV7c_ac2XZ_FDjUrlCwmM6V6UtNQWd9FGPEMRN HTH=w640-h480-s-no?authuser=0

The only difference between the center axle and the rear axle shown in the previous picture, is that the center axle uses the pinion housing for both the front and rear of the diff.


The right end of the 6" rule in the attachment shows the length of the original axle shaft. The original axle was parted off about 29mm from the inboard end of the shaft. The remaining piece of the donor axle was parted off 39mm from the outboard end of the shaft. Both the parted off ends were turned from 5mm down to 3mm. The turned stubs were about 14mm in length, this length isn't critical. What is critical is the location of the shoulder. On the inboard section this shoulder is 15mm from the inboard end, on the outboard section the shoulder is 25mm from the outboard end. These two sections are joined together with a piece of 3mm ID x 5mm OD brass tubing with a length of 30mm. These 3 parts are then glued together with the HF equivalent of red Loctite using a vee-block as an alignment jig. If I did everything right, I should end up with axles 70mm long. One measures 69.95mm, and the other is 69.97mm.

Is there an easier way to do this? You betchya! You could just cut the axle shaft with a hacksaw and glue the pieces into a piece of 5mm ID tubing, The only reason I chose the method I did is because of the way the outboard axle bearing will be installed. When I use these donor axles to build a powered steer axle, the CV joint that will be glued into the outboard end of the shaft is over 5mm in diameter. In order to install the outboard rear axle bearing it will need to be slid onto the axle shaft from the inboard end.

I've still got problems with the Sherline. First the headstock bearings are stiff and noisy. These are the original shielded bearings and I suspect that the factory grease isn't exactly greasy anymore. I've been dousing them with light oil to try to reconstitute the grease but so far without much luck. I'm thinking new bearings are probably needed.

The second problem is with the carriage lead-screw, it binds up. But only when moving the carriage toward the headstock, and only when the hand-wheel is between the 2:00 and 5:00 positions. I suspect that this is a left over boo-boo from when the Sherline took a nose-dive off the bench onto the end of the threading attachment drive dog.

[ddmckee54]

Regarding the Sherline carriage lead-screw issue, when I started taking it apart last night I discovered that the issue went away when I took the hand-wheel off. Upon closer examination of the hand-wheel and the lead-screw shaft I found a nick on the face of the hand-wheel and a burr on the lead-screw. The burr on the lead-screw was caused by the grub screw, but I've got no idea what could have caused the nick on the hand-wheel. I stoned off the raised areas and when I reassembled things that particular problem was gone.

I've been plottin' & conivin' for a while as to how I can adapt the Frankendiff into a powered steer axle. Blender's build of a 1/14 scale TH407C telehandler gave me the idea I needed. He used Losi CVD front axles to build his steer axles. Since I've already got a butt-load of the WLToys 12428 replacement rear axles I decided to get a set of replacement front axles to see if they'd be usable. After doing a little (very rough) 3D modeling, it looks like things will work out. They both use a ball and socket joint in the knuckle, but the Losi uses a CVD joint while WLToys uses a CVA joint. A CVD joint has the ball on the axle with the socket on the half-shaft. A CVA joint flips that around and has the ball on the half-shaft with the socket on the axle. Here's a picture of the WLToys CVA joints.
https://lh3.googleusercontent.com/pw/AP1GczPzc0majzWc_nN0XvZeaB0B-kU3NNvZoQuh2scq_r1eGvz_KFhgKAVbJBiqF4wmWArd_TP7Qcc 6s1VjiSaG6kmQjaY0AWj16vw97xbcUGei0Mgb4HJ9ZgSdkdEoD W8S_0UQcEsMxqNAIqtB1xBy5Qdg=w640-h480-s-no?authuser=0
At the top is the assembled CVA joint, in the middle is the axle with the socket, and on the bottom is the half-shaft. At the left is the dog-bone that would normally attach to the front diff. This 14mm section on the left is totally useless to me, I only need about the last 25mm on the right. The center section of the half-shaft currently has a 3.18mm OD. My current plan is to turn part of the center section and part of the tapered area just to the right of it down to a 3mm OD. This will then be Loctited into the outboard end of the modified donor axle, just like I did when shortening the donor axles for the rear diffs.

Edit: Due to the black finish I was worried at first that the axles might be hardened. However when I checked them with a file I found out they aren't. The dog-bone section was easily removed with a hacksaw.

[Zabco]

Lord only knows what happened to the site this time. Was completely gone this time, not even any html code showing up when I tried to inspect the site. Glad to see it's back though and hoping it holds together for awhile yet. Still the best site for real information about building trucks and equipment.

Your axle really looks good Don, great job! Also sounds like you've got a good handle on the steerable axle as well. Can't wait to see how it comes out.

As to the Sherline, I'm glad to hear that removing the burr on the hand wheel fixed the problem. Thought you might have a bent lead screw when I started reading. Don't know about the bearings. Sherline claims they are lubed for life. Course no accounting for what the previous owner did to it. May want to drop Sherline a not asking about it.

[ddmckee54]

I was afraid I had a bent lead-screw too. Yes the bearings are supposed tp be lubricated for life, but, they are shielded bearings - not sealed. If they sit for several years without being used, the grease will dry out and harden. According to the part number they are standard precision bearings. Once upon a time in the west I used to repair machine tools for a living, so swapping spindle bearings is not outside my comfort zone. At least now the parts are a LOT lighter, and they're not covered in nasty smelling coolant.

I just got done modifying the first CVA half-shaft.
https://lh3.googleusercontent.com/pw/AP1GczNGiTsY0HT5jP4h3sI73fMgb0HmZOLI0oP7m2dFlKYqCG ZEdR8SdLCMnqppxUgQJC4s_46-v8co-ZKcKh12-z8rxL2-wG5m2_3E94dmzmw9y0O-EGsZ3eLiX_nwYrnOzYejiV3rgjgZNbjXehdNShXS=w640-h480-s-no?authuser=0
The modified half-shaft is just slipped into the brass tube for now, I'm just getting started on the working 3D model that will be used to print the parts. I've got bushings and shoulder bolts on order for the knuckle pivots, so I can accurately model things now. I model things in mm because that's how most 3D printers think. I really wonder sometimes when reverse engineering this stuff, some of the measurements make no sense. Like why is part of the half-shaft turned to 3.18mm, and why is the socket bored to 7.62mm. Earlier today it finally dawned on me, 3.18mm is 0.125", and that odd 7,62mm bore is 0.3". When I convert all the odd Metric measurements to Imperial units they come out nice and neat.

[ddmckee54]

I spent most of the day yesterday fighting with Alibre locking up. I'm trying to do the final 3D design for the powered steer diff parts. The design I showed a couple of posts ago was quickly thrown together to see if I could even make it work. NOW I need to cross the I's and dot the T's so that it will all work together, and that means accurately modeling all the individual parts. That's actually a good thing as I found a couple of gotchya's while doing it.

One of those gotchya's was determining how much I needed to shrink/stretch the ends of the diff front and rear housings to accommodate the single front wheel instead of the dual rear wheels, and still maintain the same wheel track. It turns out I needed to take 13.5mm off each side. I know that doesn't make sense that I need to move the end of the diff housing inboard when going from duals to singles, but I spent a couple hours convincing myself that moving things 13.5mm inboard was actually right.

The second gotchya was when I realized that the screws holding what I'm calling the diff pivot in place (that's the part where the steer axle pivots in order to steer) would be hitting the outboard bearing - that would not be good. So I had to change the design of the diff pivot, it's now about 6mm longer. THIS change interfered with the outboard screws holding the front and rear diff halves together. Since the diff pivot slides over the ends of the front and rear diff halves holding them together, those screws aren't really needed any more. Problem solved, but I did have to change the 3D models for both halves to reflect this.

The third gotchya is what does the length of the brass tubing splice need to be? My modified rear axle measures 147mm from end to end. My modified axles were 70mm nominal in length, so that means the spider gears were occupying 7mm of space in the middle. My 3D printed non-powered front axle needs to be 172mm from end to end. If I subtract the 7mm for the spider gears, and divide by 2, the stack-up for my front axle length should be 82.5mm? (Why do I feel like Rodney Dangerfield in "Back to School" right now?)

Plus I realized that there's nothing keeping the outboard bearings of the steer axle from sliding outwards. On the rear axles the hex driver holds the bearing in place, on the front axle there's nothing but air in that location. Oh well, that's a problem for future me to solve.

Don

[Zabco]

Don't you love it. Think you got one simple change to make and it cascades into an avalanche. Good thing this is a hobby, I'd hate to have to charge someone for the time involved in some of these changes.

As to your bearing problem. Would it be possible to cut a small groove in the axle shaft just outboard of the bearing and install a C or E clip to act as a stop. This is how the bearings in Tamiya trailer axles are held in place.

[ddmckee54]

Somehow today I did something stupid. I must have changed the font size or something for this site because the text on this website is now huge. But it's only on this website, any other website appears normal, and I've got no clue how to get this back to normal.

[ddmckee54]

Never-mind, I figured it out. Somehow I had bumped the Zoom up to 200%.

I'm still fighting with Alibre's assemblies, trying to figure out what I can and cannot do with it. (I think part of the problem is that I'm NOT modeling any mechanical fasteners. This just might be what's driving Alibre up a wall.) This is a shot of the suspension assembly up to this point with the front axle just hanging out in mid air - things are shown at the approximate ride height.
https://lh3.googleusercontent.com/pw/AP1GczPIbk5NpKN2fhjYP9Vl65GmnWdsfWA-9Ad2fppX2ktgYA3BiMhpne2eXCbslyzk46eL2ilSQHKy0s5asT AD38xbAt8OEC7sjKEToBdf6FUYnlj6I2KIr8hJlUCKvWXDwv4o 2abrWb3s35ARMUbFJGey=w640-h352-s-no?authuser=0

I've got the front diff mostly complete internally, I've got the flexible CVA axles & half-shafts modeled. I haven't completely modeled the brass tubes and inboard parts of the axle shafts yet. I do have the brass tubes modeled to give me a nominal over-all axle length of 82.5mm. I did this as a sanity check to see if I had about 7mm between the axle ends like there was with the rear diffs. The distance between the axle ends measures 7.143mm - as Mr. Miagi would say "CROSE ENOUGH!"

I'm working my way out now, I've got to design the steering knuckle/steering arm widget. I've got a rough idea of what will work, but I need to refine it. It needs to fit the tie-rod in so that it clears both the top on the pinion cover, and the bottom of the frame rails - with some clearance to allow for suspension travel. Now I need to find the specs on the bushings and shoulder bolts I ordered - so I'll know what modifications they will need.

Don

[frizzen]

Ugh, this sounds like a whole lot of fun.

How often are you stopping to take a break to push that Bruder truck around while making engine noises?

[ddmckee54]

That phase will probably start when I actually begin bolting pieces to the frame rails. Instead of just making making pretty pictures on the monitor.

[ddmckee54]

I think that I just might be starting to get a handle on this Alibre assembly crap.
https://lh3.googleusercontent.com/pw/AP1GczOV53ORnUv-5w_oiqyeUPTPYuObdEQZ31M-s0WymAnDhBPOeazZ26rSfQ20_g2epDQCVCr61aYYvm5TgpWp1X ZwPnnxJZqzNj5ICjOgmccG9ooQmT2xcZfh1uTi3KvrsOuH4qh_ 45a-JkG6y8H8FOBp=w640-h333-s-no?authuser=0

You are looking at a functional 3D assembly model. I can spin the wheel on the axle. When I turn the steering knuckle the wheel moves with it, and the tie-rod brings the knuckle on the other side along for the ride.

I did have to give up on the idea of putting the tie-rod above the drive shaft though, there just wasn't enough room. Where it is currently located the tie-rod is about 4-5mm below the driveshaft and won't touch any thing trough its' full range of travel. The bottom of the tie-rod is still above the bottom of the differential though so the tie-rod shouldn't get caught on any thing.

[Zabco]

Wanted to reply to your post on the 28th Don but I was at the Lafayette RC truck show this weekend and only had access to open public wifi and I don't like submitting passwords over those.

Alibre's assemblies can be a huge PITA. Most times they fall right in place and other times they just aaaarrrrrggghh. A few things I've learned about them over the years.

You can only have 3 constraints between any two objects or assembly.

Sometimes just changing the order you create the constraints will make a difference.

Under each part listed on the work history on the left side of the screen will be a list of each constraint you created for that part as well as a list of all the constraints created for the assembly as a whole. If a constraint has failed for some reason it will be shown in red. I usually just delete these as they can cause confusion when trying to figure out how things went together.

Get one part in place, usually 0,0,0 and anchor it. If you don't you run into the possibility of parts suddenly flip, flopping around and you can't figure out how the heck that happened. And usually the only way to correct it is to delete parts and start over.

It's often easier with complex systems to make parts into sub-assemblies and then assemble the sub-assemblies in a final assembly. But there is a catch to this method. In your last post as an example, you explained how you had the steering knuckles and tie rods able to move back and forth. If you were to make that drawing a sub-assembly and then add it to an assembly of say, the entire frame, those knuckles and tie rod will no longer be able to move. They will be frozen in whatever position they were in when you last saved the file. Only parts added in the current assembly will be able to move.

I don't know to how many decimal places Alibre takes their precision but it must be quite a few. If you try to constrain two parts and the difference in distance or angle is off by the slightest amount they will not go together. For example if I want to assemble a cross beam to a frame and they both have a square 4-hole layout that bolts would be put through to bolt the parts together I would probably assemble them in Alibre by first mating the two flat faces together, then make a coincident constraint between two of the holes in the frame and the bear. But the parts would still be free to move about each other around that bolt hole. To fully fix the beam in place I need to add a third coincident constraint between another pair of bolt holes. Three point of constraint and the two parts can't move in relationship to each other. But when I designed the beam I got the distance between the two pairs of holes .0001mm shorter than the same pair of holes in the frame. Such a tiny amount of length that you couldn't see it in the real world and a bolt would still easily fit, Alibre won't accept it. Round-off errors if you do your math outside of Alibre can cause a real problem. I don't know of any setting that you can change to allow a certain amount of 'play' between parts. The same is true when trying to mate parts with angled surfaces that are already constrained to other parts.

The nice thing about the assembly window is that you can create new parts or edit existing parts within the assembly. In my example above where I can't make the third constraint because of the slight difference in distance I could edit the beam by deleting the holes in the beam, place new holes on the face of the beam and make them individually coincident with the holes in the frame and then do an extrude cut on the beam. Perfect match, constraint made and when I save the assembly file the part file for the beam will be updated.

If all else fails, make a plane and use it to constrain a part. Planes have to be created relative to another plane, face or line of an object. So Alibre knows exactly where the plane is located. You can then do a direct of offset constraint between the plane and the part or sub-assembly you are having problems with.

[ddmckee54]

Constraining things to a plane is what I do - sometimes.

I placed an axis in the centerline of the axle bores, and I've got an axis on the pinion shaft centerline for each axle. The origin for my suspension assembly is the tail end of the center of the frame rails at ground level. I've got offset planes where the center of each axle shaft should be located. I've also placed a plane at the ride height. I've constrained the axles so they can move vertically along the locating plane and the pinion axis is constrained to the YZ plane, this keeps the axle where it belongs front to back and side to side.

I constrain the axle shaft axis to the ride height plane when I initially place the parts/sub-assemblies. When I want to check suspension clearances I suppress that constraint. When working in the various sub-assemblies I will constrain the various parts to get them properly oriented, anchor the part, then delete the effected constraint/s.

I did something similar with the front axle assembly. When I was initially placing the CVA axle and the CVA half-shafts their axis were constrained to be coaxial. Once I had everything placed properly I suppressed the coaxial constraint, and constrained the axle so that it could pivot around what are effectively the king-pin bushings.

I stumbled across a "Flexible" check-box and hoped I'd found the mother-lode regarding the "moving" sub-assembly parts no longer moving issue. Alas, there was no joy in Mudville that night since it made no difference. I've been doing a little digging on-line and it seems that I was on the right track.
That option IS supposed to fix the no longer flexible issue - but it doesn't always work.

I was able to use the assemblies to check clearances, what broke the rear suspension assembly was trying to get the walking beam to play nicely. I'm pretty sure the full scale rubber bushings are there to absorb any minor alignment problems, and I've got silicon O-rings to substitute for those bushings in the model. I just don't think Alibre assemblies were designed to simulate something like that.

[Zabco]

Sounds like you have a real good handle on the assembly process in Alibre. Just wish it all would work. Where is this 'flexible' check box? I don't recall ever seeing such a thing. Or is it only in the full blown version and not in Atom?

[ddmckee54]

I've got Design Pro V22, so I don't know about Atom. In Design Pro if you right click on the assembly in the Design Explorer, you get a drop down menu - Make Flexible is one of the options in that menu.
https://lh3.googleusercontent.com/pw/AP1GczNn1ZG2PRiviiy9XDU5JToLbwBskN1D5TlyS9bx86GfaE P-q2Np9dswrX41PKS39o4ATWdl2woaSPw0QtHsRtTMcFa37h9gaB 8-eAdOa2UPyOOIWZc6t3ORUGuPx7LNyJ6H_DW5FTUhted8FjJhgG r-=w1032-h602-s-no?authuser=0

Don't know if that helps.

[Zabco]

It does indeed, last place I had thought to look. Had gone through all the preference menus and couldn't find anything. Will have to do some experimentation as I have never tried it. Weird in that I use the functions on either side of it all the time and never really noticed it.

FYI - I talked with Travis Biddle while at the Lafayette RC show this past weekend. Travis is the guy who owns this web site. Asked him how much longer the site will remain active. He didn't say when it would go dark but that it's days were probably numbered. Lack of use, number of known bugs in the program and no one wanting to hose forums anymore. If you want to save anything you've posted on here you better back it up somewhere. I've always kept copies of my postings and thankful that I never used photobucket for my images. I'll keep coming in here till it goes down but I am considering options. I already am a member on Scale Builder's Guild and they have a section for trucks and equipment. And I know there are a couple of other similar sites. Wait and see what happens.

[ddmckee54]

I know that Blender, Frizzen and I have all posted over on the Semi Truck and Construction Equipment forum of RCGroups. I'd never heard of the Scale Builders Guild until now, I just registered there. I'll have to take some time and go through it later. I never used Photobucket either, but they sure did screw up a LOT of forums.

[Zabco]

The two programs are pretty much the same. I've still got a copy of Cubify Design (from when 3DSytems owned the software) and it works the same way. I played around some today with the 'flexible' function. It does work but is somewhat persnickety about how you set up the assembly. I drew up a basic engine using 3 cylinders with wrist pins and connecting rods. A piston with connecting rod and wrist pin was created as one assembly. A crankshaft with 3 - 120 degree connecting shafts as a part, and a basic engine block as the third component. Started a new assembly by bringing in the crank and constraining it to the Z axis and centered on 0,0. Then imported three copies of the piston assembly. First I connected each piston without enabling flexible to the crankshaft with a vertical constraint. As expected, the assembly locked up with the second piston and would not rotate. Next I enabled flexibility. Connected first piston assembly to crankshaft and constrained to vertical position directly over center of crank. Piston would move up and down with crank rotation. Added second piston same way and crank would rotate. Thought that this was going to work ok. Added third piston and the assembly locked up and would no longer rotate. All three pistons were in alignment and connecting rods were free to swing back and forth. Happened to glance at left hand column and noticed I had a number of constraints shown in red meaning they were bad.

Thought about what was going on and came to realization that I was over constraining the piston assemblies. What I forgot is that they already had some constraints carrying over from their original construction. Adding the three additional constraints placed on them in the new assembly and they froze. Deleted the piston assemblies and all their related constraints. Imported the engine block and centered it in X and Y over the crankshaft and anchored it in place. The engine block would serve to align each piston directly over the crank, properly space each piston along the crank and serve as the vertical guide for the pistons. Add each piston assembly back, enabled flexible, put concentric constraint between each piston and cylinder bore and a concentric constraint between crank and connecting rod. That's all, no other constraints. Added other two piston assemblies in same manner. "Grabbed" the crank and gave it a twist and it spun with all pistons going up and down as the should. So the 'flexible' function does work but you just have to be very careful in how additional constraints are applied. And, I think, not constrain part that will move to planes or axis.

[ddmckee54]

For the last couple of days I've been working on Sherline mods. One of the mods I did earlier was to add some cheap Chinese scales with remote readouts to the carriage and cross slide, that was a game changer. But I learned some things about those scales that I wasn't happy with. First, they're battery powered and no AC adapter is available. My scales also do not have an Auto-Off feature. I don't know how many times I've gone down to the shop the next day only to discover I'd left the stupid things on. The most aggravating thing is that the carriage scale will periodically reset to zero.

I did some research and found out that the Shahe clone scales, which is what these are, can be sensitive to electrical noise - there's no shielding on these things. I did mention they were cheap didn't I? 'Cause I got two 8" scales for 36 bucks and change, including shipping. I am replacing them with Igaging EZ-View Plus scales which have better resolution, shielded cables, and an available AC adapter. I got a 6" scale, a 12" scale, and the AC adapter - all for about twice the price of the Shahe clones. As an added perk, Igaging actually gives you instructions on what scale functions are available and how to use them.

I was having trouble wrapping my head around what everything would look like, so I decided to 3D model it. For the last couple of days I've been modeling my Sherline's bed, the base I've got it mounted on, the carriage, the cross-slide, the new 6" scale and read-head, and the new 12" scale and read-head. I modeled the scales and read-heads as separate parts so they would work correctly in the assembly. Once I got the parts modeled it was time to start arguing with Alibre about what I can and cannot do with constraints in assembly drawings. I've learned some lessons from the other assemblies I've done about being methodical and renaming the constraints to something that will make sense to you in the future.

I added the base to the assembly and then I anchored it. I then added the Sherline bed, and used offset constraints to position it. Then I anchored it also, and deleted the constraints I broke when I anchored the parts. I added the carriage and used coincident constraints on the dovetails to keep the carriage in its' proper location. I then added an offset constraint between the carriage and the headstock end of the bed, and played with the limits until I had the carriage restricted to it's normal movement. I did the same for the cross-slide and got the carriage and cross-slide working together as they should.

Then I started adding scale bits that were just hanging out in mid-air; getting them to move like they should without breaking anything else. Once I had everything dancing about in a coordinated fashion I started designing the brackets that would connect Tab A to Slot B. This is where I'm at now.
https://lh3.googleusercontent.com/pw/AP1GczPJ7eAHCODPOeuCwT_mvVo-6WvezsK5B55ZHzOhibCXRSOOQwM2bYUg8TxNM5A7VpuQv18-rTug5L1tZ8NikRrH3u5lisCrsJCoNwFki_oj-zxi64Do0C16xTUkztL13j0pA7TOr7RpQRi-T97GoXqg=w640-h333-s-no?authuser=0

I've still got to finish the design of the bracket that ties the cross-slide scale to the cross-slide. The cross-slide read-head is fixed and the scale moves through it. The carriage is the opposite with the scale fixed to the base and the read-head moving on it. I still have to design the brackets that will anchor the carriage scale to the base. I just noticed that I never modeled the two existing screw holes in the carriage. I'm going to use those screw holes to mount the read-head bracket. I'll need to reposition and redesign that bracket to use those screw holes. I guess I'll have to send a change order to the customer for the extra engineering time.

Don

[Zabco]

The iguaging scales are very popular in the home machinist hobby world. If you want an even better readout google 'yuris toys'. Yuri developed a, relatively, inexpensive way to combine the scales with an old android based tablet and some and some additional hardware to create a very good DRO for lathes or mills. Has his own forum on the www.hobby-machinist.com website.

[ddmckee54]

The new Igaging EZ-View Plus scales use a different protocol than their older DigiMag scales did. I know Yuri is working on it but I'm not sure if he's got his Touch DRO working with that protocol yet.

I got the 3D design done done for the lathe scales and printed the parts out last night.
https://lh3.googleusercontent.com/pw/AP1GczOzBNRwkv5VXgHofzi1LzcvYam9IYTSgRwvJeyGp2zvUi lOPmq_bB5d3lCjSGRrl1TScd_P7FSnZWfk19vD5m22Z-TE6YfEMZ66sRSd-b-dOSp7jxFOmys6MFYumshe6OHExooxeDRXzfiouMCpdAPU=w640-h480-s-no?authuser=0

The 2 parts that I couldn't design any adjustment into are the ones that don't fit. Turns out it was operator error, I didn't model them correctly. I fixed the models and the parts are re-printing now, they should be done in a couple of hours. Then I can start installing the new scales.

After that, about the only thing left for Sherline modifications are new headstock bearings, which arrived in the mail today.

[ddmckee54]

The scales upgrade on the Sherline is mostly complete. Here's what things look like from the front.
https://lh3.googleusercontent.com/pw/AP1GczOpC-6TlzH8keOHDNKvRDFuiBGCVsqqNDg9jNKfegEncgKbKbmxObCF FOfcQqvzPx1TeOIig5HQBSSbAu5_IAqc0qcmUz9ZVEZ--aOiLX2Ek9Qt4Y3D0ompPeHvEgd_jOXG_2--xnUgUR7seNBJsj7C=w640-h480-s-no-gm?authuser=0
As you can see, I'm no longer losing 35-40mm of carriage travel at the tailstock end due to the cross-slide scale. And the cross-slide scale is no longer a shelf where chips and dust will accumulate. That cute little 000 Phillips screwdriver on the lathe base and two extra screws came with the scales, you need it to open the battery cover.

This is what the back side of the scale install looks like - from the headstock end. The carriage scale in no longer a wide shelf that chips and dirt will land on. Both the cross-slide and the carriage scale have the actual "scale" facing away from the spindle, so they aren't directly exposed to hot chips.
https://lh3.googleusercontent.com/pw/AP1GczPmGpmNBhGWIUbqQgKamtoU89Amj82L3oRuB7t6Wj7oFM H4NggkTxM4vVu5-stsfbRpI9L5oxmCKoTl7mstd-DOdsQv1vdSKerX0CKjn12B5vkbmv3_zJCbnXe_Z_vln0vEmKZ_ lE3NkpNs9EuJBri5=w640-h480-s-no-gm?authuser=0
That black object on the LH side of the cross-slide read-head is an end stop. Before I installed that, it wasn't uncommon for me to retract the cross-slide far enough to disengage the lead screw from the lead nut. While that wasn't a show-stopper, it was irritating. That won't happen any more.

This is the temporary location of the displays.
https://lh3.googleusercontent.com/pw/AP1GczP28aT9QcqhhloRnQQdISnDcoKDyycwWpAvHgsR0yfR8R e_CYr_UtgAOKsanvdvudZOsgoldVtkv1jcxIe-qREzcB7vK2bvULHkF-5q8mxGaJzLaM9T0I4YIWyiWnbpt9IJM_PZ1J925wd14lskGgjx =w640-h480-s-no-gm?authuser=0
The brackets that came with the scales didn't work for me. They allowed you to swing the display from side to side on an arm that was 8-9" long. They did not allow any tilting of the display for a better viewing angle. I 3D printed a pair of stubby arms, about 2" long, that allow me to tilt the displays to the best angle - whether I'm standing or sitting.

There's still a few things on the To-Do list:
1) Find a more permanent home for the displays. Right now I'm leaning toward mounting them on the peg-board using some of that brown non-conductive organic material - probably about where the pin-punch set is hanging behind the 3-in-1 oil.
2) Do some cable management, not gonna get crazy with the excess cable like I did the first time. Behind the peg-board is a blocked off door that at one time went into the coal-room, for when the boiler was coal-fired. I may just let the extra cable hang in that space, it's not like I can actually use the space for any thing else.
3) I've got to find another plug and get the AC adapter modified so it will be able to power both units. Somebody might already make a Y-adapter in the right size, I'll have to check Digi-Key and Allied-Electronics to find out

Like Superfast Matt I tend to get things to the point where I can use them, then they never truly get finished. But they are good enough to use, and right now this one is "Good Enough".

I've also got the replacement spindle bearings for the Sherline, I got tapered roller bearings to replace the noisy deep-groove ball bearings, That project is on the "Someday" list too.

Don

[Zabco]

Looking good Don. Like your solution to handling the cross slide scale. Can those scales be trimmed to shorter lengths?

[ddmckee54]

Yes they can be trimmed. I cut about 3" off the original scales with a hacksaw. That got the job done, but the epoxy/glass board the actual scale's on was tough to cut. I used an angle grinder and the spinning wheel of death to cut the Igaging scales, that went MUCH easier.

I found that Igaging uses SS instead of aluminum for the scale support bar, so the cut-off wheel was probably a good choice. Because I reconfigured the cross-slide scale I was able to shorten the Igaging by about 1-1/2". But I started with a 6" Igaging scale, not an 8" like the original scales.

[Zabco]

Thanks Don. Have thought about doing similar to my lathe. Couldn't do the cross slide like you did. I bought mine set up for CNC and the servo mount prevents inserting anything into the the T-slots from the front. So can't plug up the rear access. Did come with the zero reset hand wheels which helps, don't have to remember what setting I started from.

[ddmckee54]

At one time I was considering putting the carriage and cross-slide scales parallel to each other. I was thinking of using something like a Sullivan Gold-N-Rod to link the cross-slide to the scale, to simplify making the 90 degree turn with the linkage. If I remember correctly the outer casing is only about 1/4" in diameter. Something like that might work for you.

[ddmckee54]

Further development on the steer axle is on hold for a week or so. The motor/2-speed gearbox, that I initially wanted to power the model with, uses a single 370 sized motor and has 3mm output shafts. While the 370 sized motor MIGHT have been up to the task, I don't think the 3mm output shafts would have been - since all of the differentials have 5mm input shafts.

I've got an LDRC LD1201 Unimog replacement motor/gearbox ordered. It uses a pair of 370 size motors driving a 2-speed gearbox with 5mm output shafts. One of the outputs looks to be centered, and the other appears to be offset to the side. If it is offset then I'll have to slide the pumpkin to one side on the front and rear housings for my steer axle. Unless I can find some drawings on-line, I won't be able to do any more work on the steer axle until I can get some measurements from the gearbox.

[Zabco]

At one time I was considering putting the carriage and cross-slide scales parallel to each other. I was thinking of using something like a Sullivan Gold-N-Rod to link the cross-slide to the scale, to simplify making the 90 degree turn with the linkage. If I remember correctly the outer casing is only about 1/4" in diameter. Something like that might work for you.

That is a very interesting idea. I've never used a Gold-N-Rod before as i've never been into airplanes but know what they are. Thanks Don, gonna have to do some thinking on this.

[ddmckee54]

No problem.

A gentleman on HMEM suggested that if I lowered the cross-slide read-head I would free up that back corner of the cross-slide for normal use. I already had everything printed by that time and didn't feel like re-designing it - AGAIN. If I ever do this again, I'll probably hang both read-heads at the level of the carriage scale with both slides parallel. Then I'll use the Gold-N-Rod trick to actuate the cross-slide scale. I just had a thought, is the "Make Flexible" check box in Alibre to simulate a connection like a flexible pushrod?

[Zabco]

I don't think the 'flexible' option would work for something like that. It only allows movement in sub-assemblies function in another assembly but only within the limits of the applied constraints. You could model and move a straight line movement like a piston rod in a cylinder because it only moves in one axis. No way that I know of for it to model movement through multiple bends. Would be kind of neat though.

I really need to have access to both T-slots in my cross slide as I usually have my cutoff tool mounted in slot closest to head stock so I can get it as close to chuck as possible. Often have to have my QCTP in back slot depending on tool holder being used so, again, I can get cut off tool as close to chuck as possible.

[ddmckee54]

It doesn't really matter about the "flexible" setting, that was just one of those wild-haired ideas that smack me in the head once in a while - kinda like Gibbs and DiNozzo.

[ddmckee54]

Wilf on MEM got a flexible pushrod to work using SolidEdge 2025. I don't think my version of Alibre has the brains, or the brawn to handle it.

Anywho...I updated the 3D model of the chassis to use the appropriate frame rail lengths, and axle spacing, for Bruder's MAN mixer. The thing's starting to look more like a truck now, I've hidden the passenger's side frame rail so things are easier to see. I've also included the motor/gearbox so I could re-design the steer axle pumpkin location.
https://lh3.googleusercontent.com/pw/AP1GczM6J4cM1xbW9guRXACz8Q6EsjjNbCEzBe0n30NtoejqNA ziRdpM_teV6cZnoFpWdEGeGQAliAc5_HmmxG-nEFIs1PhTIU2Re_vEGdHnKbYDT9edEozLYNtzMTUk42MK_7_Hp bQgrt6ZXlG86LaG0xJA=w800-h439-s-no?authuser=0

That's done now, and we need to be verwee-verwee quiet, because we're hunting drive shafts. However, I'm having about as much luck finding one that will work as Elmer ever did getting the wabbit. I've got a couple different flavors of SCX10/TRX4 drive shafts on order, to see which will be easier to modify to fit. It would be nice if somebody made flange mount U-joints, but I don't see that happening - and I'm not building a museum scale model.

The center axle to rear axle drive shaft is the real problem. In order to be able to install that shaft WITHOUT removing an axle, that sucker needs to collapse down to under 39mm. It looks like I might as well be hunting for Unicorns. I'll probably just have to resign myself to the fact that shaft will need to be installed WITH the axle.

Don

[ddmckee54]

OK, I've found out that I'm going to have to revisit my chassis design a little. So far I've been sticking to the measurements taken off the Bruder MAN mixer, but that's gonna have to change a little. I'm going to have to modify the axle spacing/locations a little. I cannot find an off the shelf axle that will fit the existing center axle to rear axle spacing. I currently have an absolute minimum drive shaft length of 42mm. When you add in the 7mm I need to be able collapse the drive shaft to take it out. then I need a drive shaft that has a minimum length of 35mm. I was able to find drive shafts in the 30-36mm range, but they only had a 2mm ID with a 6mm OD. Nope, that ain't happenin'. I did find a Lesu drive shaft with a 5mm bore in the 45-50mm range, and have one headed my way. It costs 3 times as much as any of the other drive shafts, but none of them can be made to fit.

My current plan is to add 5mm to the spacing between the center and rear axle, and play with their locations a little so I don't mess up the drive shafts coming off the transfer case. By adding the 5mm to the axle to axle spacing, I SHOULD get into the middle of the range of motion for the Lesu drive shaft. Unfortunately it also means that the drive shaft and the axle have to be installed/removed as a unit.

[Zabco]

Well hopefully you won't have a need to remove the rear axles very often, if ever. Can't remember the last time I had to remove one of mine, or even mess with the drive shaft itself.

[Blender]

Don, in your driveshaft search did you run across any with a 4mm bore? Been looking for another project, but haven't seen much. Everything is 5mm that I found, or 4mm/3mm mismatch.

[ddmckee54]

Blender:

I sure did. Here's an Ebay listing with 5mm, 4mm, 3mm, and 2mm drive shafts - but they call them "steering shafts".
Drive shafts (https://www.ebay.com/itm/145199407330?_skw=steering+shaft+4mm&itmmeta=01JR9YDR65AZJT002MC1Q7P37F&hash=item21ce8f20e2:g:B-EAAOSwth5kuO1k&itmprp=enc%3AAQAKAAAA8FkggFvd1GGDu0w3yXCmi1dXZxvk% 2F0A9%2B1mQpX8WcWIEE3IV55vJgtW4Dda%2BlGsDH8R6aTQcn RohCB0ge%2Fmp%2BVdBH1LHz4aoiDGk0QnjUKuWGaWsYtnRJLU GkuIZPe9Xh6M8XK6i6dn73uI4aOZFLde4zeE1SbdU9cwRODbRs pPbffA3UxNnzOaHoOI1a2cuGbbF9rzoqWmCPuVJGzEK6dstt%2 B8LylFdOOES1NrjdCgGCJqyjfRJY4rsq7e3bMK0Am8GD3chG5L B26%2FeiHvTL1MhKatYBUuTlYIlaTY572XsKg23xka9x%2Bicl BXITF7hQQ%3D%3D%7Ctkp%3ABk9SR6CDt77CZQ)

The LDRC Unimog twin motor/gearbox that I'm using has 4mm output shafts, the WPL motor gearbox that I originally planed on using had 3mm output shafts. Since all of my axles have 5mm input shafts, I thought the WPL gearbox might have been a little on the wimpy side.

Don

[Blender]

That's perfect! Thanks. Even has some length options.

[ddmckee54]

One difference that I did notice between the 2 different sets of drive shafts I ordered is that one of the manufacturers wasn't particularly careful about getting the U-joints clocked properly. One of their drive shafts is OK, but the other is about 10 degrees off. I know on a full-sized vehicle, that WILL cause vibration issues. On a model that may not matter, but why chance it?

[ddmckee54]

I have found out that I needed to slightly modify my Frankendiff pinion housing design. The hole for the drive shaft's drive pin wouldn't line up with the hole in the pinion shaft. I must have fat-fingered a dimension because the outer bearing needed to be moved 1mm toward the axle shaft. I just had to decrease the extrusion that formed the nose of the pinion housing from 9mm to 8mm. While I was at it, I went back thru the design and removed anything that I'd done to optimize the design for FDM printing.

I've got a resin printer now and one of these days I gonna hafta put on my Big Boy pants and actually USE it.

[ddmckee54]

Sometimes I think Quality Control is a totally unknown concept in certain parts of the far-east. Some of the stuff is high quality, but there are a LOT of times when what you actually get is a kit of mostly usable parts. ALL of the SCX10 rear axles I ordered came from different vendors, but apparently the same supplier, and none of them were really usable when they arrived. All of them are almost impossible to turn. I chased that problem back to the fact that they arrived with an interference fit between the spider gears in the differential. I had to remove 0.3mm from the backside of each axle gear before things started to work properly. BUT, they are fixable.

I ordered some plastic bushings for the knuckle pivots on the powered steer axle I'm building. They were SUPPOSED to have a 3mm ID, it's actually under 2.8mm. Fortunately the OD is correct so they also are fixable.

I ordered drive shafts from 3 different manufacturers, 2 out of the 3 suppliers have the knuckles properly phased to minimize vibration. The third supplier... not so much. The knuckles are are least 10 degrees out of phase, and I'm not sure if there's going to be any fixing it.

And then, I've got a gotcha that's kinda my own creation. ALL of the drive shafts that I ordered are SUPPOSED to fit an SCX10, come with a 5mm bore and have drive pins that are threaded M4 on one end with the other end turned down to 2.5mm. My axles are SUPPOSED to be SCX10 replacement axles, but they all have holes for 2mm drive pins in the 5mm OD pinion shaft. I could bore the pinion shafts out to 2.5mm, since the Kong axle that I have has a 5mm pinion shaft with a 2.5mm drive pin hole. The Unimog replacement twin motor/2-speed gearbox that I got as a power unit has 4mm OD output shafts that are threaded M2.

So, here's my first dilemma, do I modify the pinion shafts? Or, do I modify the drive pins? Initially I was leaning towards modifying the drive pins, now I'm not so sure. If I modify the pinion shafts, I just punch the drive pin holes out to 2.5mm and call it a day. If I modify the drive pins by turning them down to 2mm, then I also have bush the hole in the drive shaft down to 2mm. Otherwise they'd be, to quote Wes from Watch Wes Work, "floppin' around like a hot dog in a hallway." Metal fatigue would probably cause the 2mm pin to break off in a short time. I think I just talked myself into modifying the pinion shafts.

My second dilemma is that the output shafts on the Unimog transfer case have a 4mm OD. Bushing the transfer case end of the drive shaft down to 4mm is no problem. They also have a pre-machined flat that is threaded M2. My first thought was to bore the M2 threads out to 2mm, since they are effectively that size now. I was planning on just having one drive pin that would work on either end, but that's just gonna make a lot of extra work for myself. I think what I'll do for the transfer case drive pins is cut a chunk off the 2.5mm end of the pin and turn the stub down to about 1.5mm - or whatever will fit in the M2 threads. The set screw on the flat will be the actual clamping/driving force, the little stub is just extra insurance if the set screw comes loose.

Don

[ddmckee54]

Lesu makes a driveshaft with a 40-45mm range, but I've only got 37mm between the center axle and the rear axle. If I move the center axle forward it will center the tires better in the fender. However, if I do move the center axle forward then I won't be able to collapse the driveshaft from the transfer case to the center axle far enough to be able to install/remove it without taking something else out. I can't move the transfer case because it's currently centered between the front and center axle, allowing me easy access to both drive shafts.

So what am I gonna do? I'm gonna leave the center axle right where it is, but everything else that's behind the cab is getting moved back by 5mm. The mixer, the fenders, the rear axle, the tail-lights, the whole schmear. I checked my 3D model and the only parts that I really need to change are the frame rails, and the equalizer beams, which all need to grow another 5mm in length.

While I was modifying things in the 3D model, I fixed a few other things. When I started working on the Frankendiff I didn't have a resin printer, so I just optimized everything for the foibles of an FDM printer. Now that I have a resin printer I don't have to do that anymore. Unless I'm actually going to use the FDM printer that is, THEN I'll need to. Re-designing the equalizer beams was not an issue, I was never happy with them anyway. I was never satisfied with the appearance of the first layer that was printed on supports, and there's NO way to print those beams without using support. So I just made the inside of the beams flat and didn't need any support. I haven't determined where the vast majority of the holes in the frame rails actually need to be yet, so changing the rail length was no big deal.

Maybe on the next truck I'll get ambitious and assign parameters to everything so I can design future chassis parts by filling in the blanks on a spreadsheet. This one's gonna be a little more old-school. Not clay tablet and sharp stick type old-school - since I am using 3D CAD to design it, more like 80's and 90's type old-school.

Don

[Zabco]

Can't wait to see what you can do with the resin printer. I bought one about 3 years ago. It was an older model Creality that was on closeout sale from my local PC store. I mostly just use it for fine detail parts like light buckets and control panels that don't get any strain put on them. Wish it had higher resolution but for <$100 new I'm not gonna gripe too much. Nice not to have to do all the post processing FDM often requires.

[ddmckee54]

I had wanted a resin printer for years, but had a tough time deciding to pull the trigger on one - couldn't justify the cost. Then I stumbled on an Ebay certified refurbished Halot Mage S for under $200, well that was an offer I couldn't refuse.

[Blender]

I really like the resin printers. A lot more time spent cleaning before/after, but the parts should be awesome.

[ddmckee54]

Remember that saying, "May you live in interesting times"?

Well, it's been an interesting couple of weeks - my car got totaled. Nobody got hurt, and no charges were filed, but I've still gotta find a new set of wheels. I've been a gear-jammer for over 50 years, but trying to find a car with a stick-shift is like looking for baby unicorn poop. Between yard-work and vehicle hunting I haven't had time to do much else.

Don

[frizzen]

That sucks! I hate when life keeps getting in the way like that.

There really aren't many vehicle with a manual gearbox, much like finding something rwd
I'm glad everybody was ok

[Zabco]

I honestly don't know if anyone makes a car today that can be imported or driven in the USA that is available with a manual shift. If there is one it is probably such a cheap POS that I don't think I would want to ride in it anyway. I hear you about the gear jammin. Drove 5x4, 10 and 13 speed road rangers and others for many years. But now living where you can't go more than two blocks without hitting a traffic light I don't really mind the 10 speed automatic in my Bronco.

Glad to hear you are ok.

[ddmckee54]

The Jeep Rubicon and the Subaru WRX are still available with a stick. Up until '23 the Jeep Renegade was available, but then they phased out the Renegade in the states. I had 169,000 miles on my Renegade when it was totaled. The worst part of this whole thing was that last year I put $7K into that car so that it would be road-worthy throughout my retirement.

[Zabco]

I feel your pain there. I'm hoping that I've also purchased my last vehicle.