TH407C Telehandler 1:14 scale

[Blender]

Originally Posted by Zabco

Ah, that makes sense. Looking at your parts they looked to be too smooth and shiny for fdm unless you post-processed the heck out of them and I couldn't see resin parts being strong enough for that application. Hadn't heard of those materials before but will keep them in mind for the future. How is Xometry to work with? I used Shapeways a few times until they went under. Supposed to be making a come back but we'll see.

Modern Resin parts are not too bad. They make a chalky dust when drilled/ filed. Some print vendors only offer generic version of the above material. I can't really tell a difference in practical use.

I was also a die hard Shapeways user. Their stainless steel sintered bronze and lost wax cast brass parts were amazing. I used the brass to fix the hinge on my ZX245 with great results. I was sad to see them go, but was disappointed how they handled the bankruptcy. That is what brought me to Xometry. They have similar capabilities in terms of printing and their machined parts now use the same quoting template. Printed part cost is similar to shapeways, but lead time is faster at Xometry.

Used to use Hubs.com for machine parts for my full size 4x4. They got bought by protolabs and are not as well priced anymore. I still have them quote stuff once in a while

I also use Autotiv to print parts. Their pricing is hit or miss. Sometimes very affordable, other times it's a go-away price. They make nice pieces and are responsive via email. Their machined part lead times are long. They are East coast based which isn't great for me.

Machined parts at Xometry are made overseas, but have a 7 day lead time. Add ~3 days for international shipping (included). Not bad.

Originally Posted by ddmckee54

Blender:

Any chance you could give us family picture, as an exploded view, of the parts in that axle? I currently don't have any plans for a 6x6 version of my Frankendiff axle, but... I'm not above "borrowing" a good idea when one comes along. Your use of that Losi axle as a starting point certainly qualifies it as a good idea.

Ya know.... I never REALLY was happy with my N20 gearbox solution for the axles when I was working on my Bruder Manitou conversion. Maybe I need to pull that guy out of the box where it's been "resting" for a while, and take a fresh look at it.

Don

I've driven it around in a past incarnation. It's workable. Not really a machine that will travel across a large course. That's what trailers are for. In tight spaces unloading jersey barriers I think it will be OK. Won't be able to dig or load a dump truck. The Lesu MCL8 is only slightly better in term of drivetrain. No room in there to swap parts out, so it stays stock.



I didn't include the hardware, drive pins, etc since I didn't model it. I'm not making a production-quality drawing package here. Originally i was reusing the Losi MRC steering knuckles. They have a different drive pin location than the MiniT CVD stubs. That's why the picture a few posts up shows the grey printed steering knuckles are deeper. Also lets the bearing space out a bit.

[Blender]

while i'm here I did rough in the front steering. Not really fan of how it looks. Works OK, but the M2 rod ends are very sloppy.


This got me thinking.... can i make the steering more scale. Full size machine uses full hydro steering. I won't like the way that drives, so I need to keep servos. Looking at swapping in rack and pinion steering to kind of mimic full hydro look. Rack gears can be bought at SDP-SI. Their metric flavors are lacking, but English size is OK. Might as well build a scale inner tie rod to omit the sloppy rod end. Had to test this part out to verify I can do it. Pinion will mount to a servo horn and be cut down to a sector gear.





3mm ball bearing drilled/reamed to 1.5mm at ~2.2mm depth in the lathe. Welded to a stub of stainless rod. Sits in a socket cut using a 3mm ball ended endmill. Makes a nice fit. Rack is 0.25in diameter. The have smaller diameter, but it doesn't play nice with the 3mm ball size. I'm not sure i can go any smaller than 3mm. Rear will be improved a lot with this. Less bump steer and easier to assemble.

Will need a chassis rebuild to fit. Need to recut the chassis to get the Leimbach pump bolted down anyway. Will make a couple other tweaks at the same time. Nothing like almost starting over

[ddmckee54]

Thanks for the exploded view. One more question. What's the OD of the Losi axle stub that goes into the coupling which connects it to the N20 gearbox?

Thanks,
Don

[Blender]

The MIP CVD losi axle where it goes into the coupler is 2.40-2.62mm diameter. It's a bit smaller near each end and largest at the center. Must have deflected while MIP machined it. 2.5mm nominal. That's the bummer since i made my couplers 3mm to fit the MRC parts

For comparison the losi LMT18 axle is less consistent diameter in the same region which was my main reasoning for not using them despite being less expensive.

[ddmckee54]

Thanks Blender, you've given me an idea for modifying the axles in my Frankendiff. Now that I've got the remote readouts installed on my Sherline I can get back to working on the diff.

I will still need to shorten each axle by about 30-ish mm, but my new idea cuts the required machining steps in half.

Plus, thanks to your input, I've now got a handle on making a powered front axle.

[Zabco]

Shapeways is apparently back in business with a couple of it's original investors now back and running the show. Their web site is back up and running. They seem to have everything except the store where you could buy designs. All that data was apparently destroyed/lost in the bankruptcy. They did buy up another site similar to thingiverse and pritables called Thangs.com though.

[ddmckee54]

Blender:

FYI - I got some of the front axles for the WLtoys 12428 1/10 scale 4WD crawler. I wanted to see what they looked like, and also to determine if using them would make it possible to build a powered front axle. They have a slight taper from the inboard end at about 2.5mm to about 3.1mm at the outboard end next to the joint. (They look very similar to the Losi axle.)

Now that I finally figured out the secret to getting the screw loose that was holding the gear on the donor rear axle shaft, 10 minutes in a 300 degree F oven, making a powered front axle is very do-able. It will require some minor redesign of the axle housing, but that will just keep me off the streets and out of trouble a little longer.

[ddmckee54]

Blender:

Got a couple of questions for you. What are you using for the steering knuckle pivots on your axles? It looks like a socket head cap screw of some sort? Do those pivots just thread into the resin housings, or do you have some type of insert in there?

Don

[skeeter]

FANTASTIC build!

[Blender]

Originally Posted by ddmckee54

Blender:

Got a couple of questions for you. What are you using for the steering knuckle pivots on your axles? It looks like a socket head cap screw of some sort? Do those pivots just thread into the resin housings, or do you have some type of insert in there?

Don

Stock losi mini rock crawler hardware is a flanged metal bushing and a unique socket head cap screw with M2 threads, but a 3mm diameter shank. The screw cinches the flanged bushing to the housing and the knuckle swings on the bushing. Bolt does these into the housing. No insert. Works fine, but I can't get replacement parts anymore. Grabbed some bronze rod to turn some spares, but haven't started.

Anything that keeps us out of trouble is time well spent.


Can kind of see the bushing under the screw head and the flange near the axle housing.

Originally Posted by skeeter

FANTASTIC build!

Thanks skeeter. I've been slacking the last few weeks, but I am still going, at a slow pace.


Got the gears on the servo horns. Took a few tries to drill/tap the first one


The 2mm stainless steel tie rods are a bit too hard to thread. Thought I bought annealed, but maybe not. I need to remake the batch in 2mm carbon steel since I have some on hand.

Also cut down the leimbach motor mount. I like their design, but it wastes a long of length. I think I cut 6mm from it. Now it's limited only by a different shaft coupler inside.

[ddmckee54]

Blender:

Thanks, I was thinking about using a small shoulder screw for the pivot. They are available in thread sizes down to M2, usually made of 304 stainless. The M2 shoulder screws have a 2.5mm OD shoulder, and the M2.5's have a 3.0mm shoulder OD.

[wedicotrucker]

That's some a long way since I saw it last. Good to see your making some pretty good headway on this little unit.

[Blender]

Originally Posted by wedicotrucker

That's some a long way since I saw it last. Good to see your making some pretty good headway on this little unit.

Thanks! I've lost a little of my momentum, but I am making progress still.

Latest task was redesigning the chassis to fit the rack and pinion steering. While I was in there I made room for a leimbach pump/custom reservoir and upsized the lift cylinder from 10mm to 13mm to account for the possible lower pressure. Boom had to be rebuild to change one part that I can't easily cut out for the bigger cylinder.

I also made a little tweak to fit lesu MCL8/skidsteer implements. Forks are my only plan, but technically I could attach anything. No aux hydraulics so the fun will be limited. I may try to get some wires routed to run electric accessories.

Axles, body, cab will all bolt on with no changes. Despite how it looks it closer than ever to running. Front steering works great. Rear needs a little tweaking, but nothing major.

[Zabco]

That is really looking good. Love the rack and pinion steering setup. Can't tell for sure from the short videos, you have limit switches on the pinion drive motor to protect it? Odd looking plate on front of pinion gear.

[Blender]

Originally Posted by Zabco

That is really looking good. Love the rack and pinion steering setup. Can't tell for sure from the short videos, you have limit switches on the pinion drive motor to protect it? Odd looking plate on front of pinion gear.

Thanks Zabco

Pinion is actually driven by a servo so it has all the built in limits and self centering. Front of it is an aluminum servo horn. OD was cut down a little and there are a few extra holes in the face from me measuring wrong repeatedly

[ddmckee54]

Blender:

The extra holes are un-documented features. If Microsoft can get away with it so can we.

Don

[Zabco]

Originally Posted by Blender

Thanks Zabco

Pinion is actually driven by a servo so it has all the built in limits and self centering. Front of it is an aluminum servo horn. OD was cut down a little and there are a few extra holes in the face from me measuring wrong repeatedly

Ok, now I fully understand what you've done. Great idea to save for future reference.

[Blender]

Sorted out the binding at the rear servo and that tightened up some of the freeplay in the splines. Assembled the steering to try it out. Rear knuckles need higher mounting point to prevent binding when acticulated. Easy fix. Inner tie rods will need threadlock for final assembly.

Ackerman geometry was only mediocre in CAD, but looks to function pretty well. Neither tire scrubs when rolling through a turn. I like it. 2S lipo on the drive is justright speed wise. Good control. Slow if running on the "road" with trucks.







Couplers on the axle shaft are a press fit, but do spin under high torque. Pinned one pair with a 1mm stainless steel rod. Buggered up the ends with the welder to retain them. Need to do the other pair.

Also got my sherline mill out of storage and freshened up. Nice to have a capability again. Been eyeing DRO systems after reading ddmckee's conversion.

[Blender]

Also removed the counterbore of another Leimbach valve set. These are the mini sized. Way smaller, but not enough to fit a 4th spool. The factory counterbore at the pump and tank connection don't work with my SMC 90 deg fittings, so I machined a little pocket.



Will use the stock pump tank for first run, but will try to build my own out of welded stainless. If that leaks I'll have the tank printed as MJF nylon.

Boom is coming along tacked together, but need to turn some spacers to (re)build the tilt mechanism.

[ddmckee54]

Since you have a gearmotor for each wheel are you doing any mixing to get some differential action?