TH407C Telehandler 1:14 scale

[Blender]

This project has been on and off for over a decade. It's closer than ever, but in a way i'm starting over. Original chassis in 2014 was brazed together. It worked well, but was not very square. My fabrication tools and abilities have improved a lot. The hand built models on the larger forums are always interesting to follow. I present my own build to you all. I hope this thread will keep me motivated as to not disappoint you all.

In the last incarnation I was able to operate the basic functions of the model. Lift tilt, drive and steer all functioned, but not to full ability. The 4WD was never connected and the hydraulic pump would run pretty hot. Body was only partially done.




That Machine still exists and many parts will be stolen from it. I split a solder seam on the boom years ago which was unrepairable since it was fully painted. The boom was rebuilt, but that showed how wonky the original chassis was. New chassis is slightly thinner material (1.5mm) and now stainless to prevent rust in hard to paint areas. CAD design was adjusted and reordered. Tiny welder did its job well. This time I was ultra careful to ensure components are placed perpendicularly using a machinists square. A few internal plates were added to ease cable routing and prevent a messy look when the boom is lifted. Rear steering was entirely redesigned to help fitment and serviceability. A little lower steer force is the cost when switching to a much smaller servo. Drive was originally N20 gearmotors 1 per wheel. This is preserved, but i will use a left and right ESC channel to allow mixing to slow the inner wheels.

Previous Losi Mini Rock Crawler CVD axles were used, but sadly no longer available. I do have 2 pairs on hand, but fear any kind of breakage. Instead Mini-T CVD shaft might be a viable substitution. Steering knuckles will be redesigned to incorporate. Lastly, The Magom HRC pump produced good pressure, but ran too hot. Start-stop pump operation was difficult because motor torque was too low with the alternate required for fitment. A larger diameter outrunner was sourced: Gartt ML3508 415kv. This is the smaller brother to the Garrt outrunner in my Metal Hobi excavator. It handles low idle very well and build very little heat. I hope for similar results in this machine.

Last generation I hit a roadblock with how to build the tubular cage of the cabin. I want it to be metal despite styrene being much easier. A simple techique used in full scale tube bending was applied to 4mm stainless steel tube. A simple tube bender and a end clamp produced favorable results. Once again the small welder will be used to assemble this structure.


Will be painted in Sunbelt rentals scheme.


Building 2 identical machines.


Tiny welder did good work. Central tabs will be body worked before paint


Boom which was rebuilt 2 years ago. May rebuilt yet again to make incremental improvements.


Larger Gartt outrunner. Every bit of space was used to fit this. Hole in chassis plate will be sealed from below via access cover.



Current status. Reprinted engine cover with slight geometry change. Shows one tube of the cabin guard. Need to rework CAD model of cabin to allow battery acces via small door. Battery is on order now 2S 4000mah transmitter lipo.

[Blender]

On to the breakthrough of how to fabricate small tube: I used 4mm annealed stainless steel tube. It's very thick wall ~1mm. Comically expensive so i am looking for alternate sources. This should weld very well and not rust while i work slowly. Cuts ok with a jewler's saw or hand file, but certainly work hardens along the way.

First order of business was to add a clamp to the Dubro style bender. I 3D printed a resin block. It holds tight enough once clamped down with M3 screws.


Block installed on an aliexpress 4mm tube bender. Likely identical to the Dubro5/32" model. This allows an index point that is repeatable shown as red on the tube


Print a 1:1 scale pattern of the part to build. Use a test bend scrap bend which the index point was marked before hand. Line up the one leg and as much of the bend as possible. Mark the tube's index point onto the paper template. Repeat for all bend locations.


Transfer each index point onto the tube one at a time before each bend. Keeping everything in-plane needed a little bit more attention than i gave it.


End result is cut to length and laid over template. A little hand forming was needed to dial it in. Not bad for a first attempt. Slightly out of plane on the second bend, but workable.

This is reassuring that the tubular body that held me back for so many years can be built afterall. This is starting to light a fire so to speak.

[ddmckee54]

Don't worry about disappointing us, most of us have at LEAST one or more of those long term projects.

I'm guessing that you had the parts laser cut, is that expensive? A couple of years ago one of the fabrication outfits that I used to work with bought themselves an industrial laser. The presented everybody in the Engineering department at the plant where I was working with their own personalized laser cut and engraved Stainless Steel nametag for their desk, as a way of showing what they could now do.

It's REAL easy to screw up when you're doing multiple bends in a piece of tubing. Years ago I went through a LOT of SS hydraulic tubing when making repairs on hydraulic lines. You don't really notice that you got your bender out of alignment until a couple of bends later. You might want to clamp a reference block onto your tube someplace while you're bending it. That would give you a reference surface to check against when setting up the next bend. If you are doing in-plane bends like that, a couple of 3D printed jigs to hold the tubing and bender in the correct orientation might make things go a little easier.

Don

[Blender]

Originally Posted by ddmckee54

Don't worry about disappointing us, most of us have at LEAST one or more of those long term projects.

I'm guessing that you had the parts laser cut, is that expensive? A couple of years ago one of the fabrication outfits that I used to work with bought themselves an industrial laser. The presented everybody in the Engineering department at the plant where I was working with their own personalized laser cut and engraved Stainless Steel nametag for their desk, as a way of showing what they could now do.

It's REAL easy to screw up when you're doing multiple bends in a piece of tubing. Years ago I went through a LOT of SS hydraulic tubing when making repairs on hydraulic lines. You don't really notice that you got your bender out of alignment until a couple of bends later. You might want to clamp a reference block onto your tube someplace while you're bending it. That would give you a reference surface to check against when setting up the next bend. If you are doing in-plane bends like that, a couple of 3D printed jigs to hold the tubing and bender in the correct orientation might make things go a little easier.

Don

Laser cut isn't too bad cost wise. Both chassis were $180 shipped from Send Cut Send. Carbon steel is less, quantity discount starts at qty 2. Used to use a local water jet shop which was a bit cheaper, but an hour drive each way to pick up parts. Started looking at Osh Cut aswell. They have more thin material options around 0.5mm, but look to be a hair more per part.

A reference block on the tail end of the tube is a great idea. Simple and gets me some multiplied accuracy depending how big it is. All my bends will be in plane which makes it as simple as I can.

[Zabco]

Very cool build. I will be closely watching as you progress. Really nice to see a new project being documented like there used to be on this site.

[ddmckee54]

Originally Posted by Zabco

Really nice to see a new project being documented like there used to be on this site.

I know what you mean, it seems like there's only a handful of us that are regularly checking in on the site anymore.

[frizzen]

Great looking chassis! That looks like it'll be a really solid machine

If the stainless tubing doesn't work well, brass might be easier to work with

[ddmckee54]

Brass is easier to work with, but Blender uses a jewelry welder to stick things together. You can solder brass, but it's crap to try and weld - the zinc boils off.

Steel brake line might work though. It's cheaper, available in a lot of sizes, just about every auto parts store will carry it, and it doesn't work harden as easily as some flavors of stainless will. It won't polish up as nice as stainless though.

[Blender]

Originally Posted by frizzen

Great looking chassis! That looks like it'll be a really solid machine

If the stainless tubing doesn't work well, brass might be easier to work with

Thanks frizzen

Originally Posted by ddmckee54

Brass is easier to work with, but Blender uses a jewelry welder to stick things together. You can solder brass, but it's crap to try and weld - the zinc boils off.

Steel brake line might work though. It's cheaper, available in a lot of sizes, just about every auto parts store will carry it, and it doesn't work harden as easily as some flavors of stainless will. It won't polish up as nice as stainless though.

Agreed brass is way easier to work with. Been able to weld a couple parts as brass. Was way tougher. The soot ddmckee brings up is for real. Stainless is a pain to shape. Some specialty hand files work pretty well. Welds like a dream though

Best bead I could get on brass exhaust pipe for the zx245.

I'm out of town visiting family for thanksgiving brought the parts with to paint. The green is so thin it barely covers. Too messy to do at home.



Nothing is wetsanded or polished. Straight from the can. It'll certainly get scratched up during future build steps. Facets from the stl are visible.

Next step is a more CAD work to add the battery door for the cab and a few metal brackets for the cage. Then lots more parts will be ready to assemble.

[Zabco]

Always wondered how well those little tig machines could do brass. I use a lot of brass but have always silver soldered it. Have you ever tried it with aluminum? Happy holidays.

[Blender]

Originally Posted by Zabco

Always wondered how well those little tig machines could do brass. I use a lot of brass but have always silver soldered it. Have you ever tried it with aluminum? Happy holidays.

Best result with brass would be some weld beads to fixture, then flow the solder over it for more strength imo. Decorative welded brass has been fine.

I had terrible results with aluminum. Tried all kinds of alloys and a couple filler materials. Dialed settings every which way. It has a setting for aluminum so I figured it would be easy. I gave up all together.

Brass and silver solder is tried and true. In a way the nice solder wicking and resulting shape is the most scale result. Fixturing was always hard for me, so I swapped to carbon steel so I could use magnets to align. Worked fine, but I'd usually accidentally solder the magnets to me workpiece. So much time spent waiting for things to cool after one joint made.

[Blender]

Nothing like cutting up a new motor. Had to skim cut the back face and the outer edge to fit the chassis


Pressed out the shaft using the lathe and adjusted the length of both sides. Ran true once reassembled, but did take a few tries to knock out the metal shavings tangled in the windings/magnets. Silky smooth now


Smaller motor coupler lets it all fit. Test run had the motor starting up smooth and stayed cool. Bad news is I need another pump for the second machine and the latest models are slightly different.


Welded up two new booms. Now they're stainless so in inside in raw, but won't rust. Previous Gen boom had weld through primer inside, but it didn't slide smoothly enough for my liking. Also added the continuous surround on the end. First soldered boom split right there when I was wrestling with the telescope. Should be much improved.


Experimented with some adhesive backed strips of UHMW plastic as a guide face. Works well on the raw inner faces.


Second set of tires were originally destine for another project, but they may get used here. Shorter but wider with a really nice tread. Wheel fitment will be critical.

Cab cage is waiting on a printed cab shell welding jig.

[frizzen]

Looking like really nice progress!

I like that your setting up the rental machines differently to help meet customer needs. Floatation tires vs High clearance AG tires.

[Blender]

Rear servo actually fits. Based the chassis of listed dimensions, which was a gamble. Rear servo has way less torque than before in order to improve fitment. Should drive okay since the back end is pretty light. 50-60 oz-in should be plenty.



Made a set of couplers to attach each wheel's gearmotor to the CVD joint. Previously the bores were just cut with a twist drill. Results were OK. These were brought to ID with a proper reamer. Day and night difference. It's like the right tool matters. Set screws are M2 such that they fit within the 6mm OD. These couplers nearly fit in the axle housing so the exterior must be smooth. Normally I'd mill a flat and drill on my tiny mill. I left it at my folks place since I don't use it much. Instead these were made on a tiny drill press. I've been using the stand up machine at work, but it has too much runout for 1.6mm holes. My sherline mill is too cumbersome to use as a drillpress. For about a year I've been looking for something a little nicer than the harbor freight or home depot grade drill press. The price gap is huge to get into a Dumore or similar. Proxxon was interesting, but I'm not totally sold. For awhile I even planned on another identical sherline mill, but keep it manual to let it function as a drill press and simple mill operations. Decided not to. Instead, the China special. I'm pleasantly surprised with it. Baseplate is just about the size of my hand print. Spindle runs true, motor/belt will be easy to modify later. $80. Anything bigger than 4mm is best done on a fullsize machine. It's a timing belt, so it does not slip if a drill grabs the workpiece. Grabbed the optical centerpunch I've been lusting for from McMaster. Should have done that years ago.



Cab's overhead protection is coming together well. Did have to re make the slightly out of plane main tube. It just wouldn't fit right. The plastic bottom structure and the little roof were used as jigs to weld it all together. The 1mm anti-intrusion bars ended up being assembled a little differently than I planned. Final 4mm round tube will get welded in underneath them. The square sections are solid stainless. Total pain to work with, but I got it eventually.

Seat steering wheel and driver figure will be added. Thought I had one more Tamiya driver figure, but I can't find it. I'll build the seat to match that figure. Cabin will be open style with not much detail beyond some basic faux controls and guage stickers. No door, or windows. Tail lights will be installed, although headlights are a maybe. Roof rotary beacon provision is already integrated into the tiny roof.





Boom and telescope both have plenty of travel remaining


No extra room. Receiver will sit on the gray shelf. All the ESCs will need to be in the cabin voids.

Been operating the hydraulics with the big motor. Runs well, but the system is weak. Pressure was 175psi and can be bumped up to an even 200 psi, but is still way weaker than it was last time it ran. Before it would do 250 psi and the lift capacity was way beyond what it could stabilize. I need to pull it all out and bench test it. Off the hip I'm thinking the pressure relief spring is to blame. Teardown will tell.

[Blender]

Spent some time troubleshooting the hydraulics. Pump would deadhead at 200psi. Valve block would deadhead at 75 psi. One of the unused spools wasn't zeroed. Fixed that and get 100 psi at the cylinder port. Not much change in terms of lift force. I did disassemble this valve block to mill one face for fitment. Maybe I put it together wrong. Dug out my old leimbach 2 spool valve. Same results. Lastly connected a new lesu 4 spool. That reads 125 psi at the port. I do expect some pressure drop in the valve, but not that much. Machine ran well before being boxed up with same hardware except for motor. Cylinders don't leak down. Pulled up old images to confirm I was using small 2mm line to each cylinder with good performance. No foaming of the oil in the tank. Clear lines show no air in the system.

I'm still suspicious of the pump. PRV spring measures at 5.5mm free length. Replacements state 10mm, but the design might be different. They also updated the gears to steel from brass. Mine are dark on the backside of each tooth, but no other damage. Don't have a an alternate pump to test with right now, but is on order. Fumotec valves will kind of fit with some work.

Plenty to do on the body, drive and steering in the meantime.



Made tail light mounts

Seat is a high back out of a semi truck for mockup. Looks really good with the boom down.

[Blender]

Back on the drive line:

Losi MRC shafts are no longer available. Instead of having each machine use a different axle I'll rebuild them both to use MIP MiniT CVD. Stub axle is longer than previous so I'll hide it in a dummy hub. Gives an excuse to swap to lug nut mounted wheels while also tightening up the wheel fitment. Will get a cap over the giant M3 nut

One aluminum hub took me way too long to cut myself, so I farmed it out for a reasonable rate. 12 hubs are in hand. Nicer than i expected.











Magom cylinders + Pump arrived. My previous pump is just worn out. New pump (upper) is a totally different design and not well suited to swapping the motor. Motor shaft has a detent pressed in to drive the pump pinion. Low parts count, but too much effort for me to mess with. May revisit Leimbach pumps or maybe a premium Kampshoff. The Leimbach motor attachment is pretty slick as shown. Would be easy to cut down their mounting adapter or make a fresh one to minimize OAL.

Focus is getting the 4WD and steering connected up. That will remain no matter what the hydraulic end up morphing into. I have to re-cut all the axle motor couplers since the new CVD are 2.5mm instead of 3mm like the previous.

[Zabco]

Looking good, I like the axles. What kind of plastic are you printing those parts from? Nice thing about these machines is that you don't have to make some kind of suspension system for them.

[Blender]

Originally Posted by Zabco

Looking good, I like the axles. What kind of plastic are you printing those parts from? Nice thing about these machines is that you don't have to make some kind of suspension system for them.

The white parts are SLA Accura 25. Supposed to be similar to an injection molded polypropylene. The grey parts are also SLA but Accura Xtreme Grey which is similar to an injected molded ABS. Both are from Xometry.com

I'm happy to avoid any such suspension. Much simpler this way with just a pendulum rear.

[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.

[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