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Re: 1/16 Scale FrankenDiff
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...-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 |
Re: 1/16 Scale FrankenDiff
Cool ideas, will be very interesting to see how they work out.
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Re: 1/16 Scale FrankenDiff
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 |
Re: 1/16 Scale FrankenDiff
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. |
Re: 1/16 Scale FrankenDiff
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 |
Re: 1/16 Scale FrankenDiff
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...-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...-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...-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...-no?authuser=0 Don |
Re: 1/16 Scale FrankenDiff
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 |
Re: 1/16 Scale FrankenDiff
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
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Re: 1/16 Scale FrankenDiff
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.
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Re: 1/16 Scale FrankenDiff
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 |
Re: 1/16 Scale FrankenDiff
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. |
Re: 1/16 Scale FrankenDiff
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. |
Re: 1/16 Scale FrankenDiff
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? |
Re: 1/16 Scale FrankenDiff
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 |
Re: 1/16 Scale FrankenDiff
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. |
Re: 1/16 Scale FrankenDiff
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.
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Re: 1/16 Scale FrankenDiff
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 |
Re: 1/16 Scale FrankenDiff
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 |
Re: 1/16 Scale FrankenDiff
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. |
Re: 1/16 Scale FrankenDiff
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. |
Re: 1/16 Scale FrankenDiff
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 |
Re: 1/16 Scale FrankenDiff
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 |
Re: 1/16 Scale FrankenDiff
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 |
Re: 1/16 Scale FrankenDiff
:D If I am going to have unfinished projects, everyone must. Excited to see where this goes
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Re: 1/16 Scale FrankenDiff
Thought they were all unfinished projects, mine are.
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Re: 1/16 Scale FrankenDiff
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. |
Re: 1/16 Scale FrankenDiff
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. |
Re: 1/16 Scale FrankenDiff
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...-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...-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 |
Re: 1/16 Scale FrankenDiff
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.
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Re: 1/16 Scale FrankenDiff
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. |
Re: 1/16 Scale FrankenDiff
After 10 minutes in the oven at 300 degrees F, and we have a winner.
https://lh3.googleusercontent.com/pw...-no?authuser=0 Being able to do this should make things a little easier for Future Me. |
Re: 1/16 Scale FrankenDiff
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. |
Re: 1/16 Scale FrankenDiff
OK, there has been a little progress made.
https://lh3.googleusercontent.com/pw...-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 |
Re: 1/16 Scale FrankenDiff
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?
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Re: 1/16 Scale FrankenDiff
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. |
Re: 1/16 Scale FrankenDiff
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. |
Re: 1/16 Scale FrankenDiff
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...-no?authuser=0 |
Re: 1/16 Scale FrankenDiff
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.
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Re: 1/16 Scale FrankenDiff
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...-no?authuser=0 From this angle you can see they're too narrow by a couple of mm. https://lh3.googleusercontent.com/pw...-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. |
Re: 1/16 Scale FrankenDiff
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...-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...-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. |
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