The Craftmans Shop > Radio Control Models

Tracked Cat delta skidsteer

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I made up a battery adapter cable last night, no pictures, basically it's a 3-way wye.  One power feed to the TREX board for the drive motors.  One power feed to the TREX Jr. board for the bucket lift and tilt motors.  And one power feed for the cooling fan, I'll see if the 12VDC fan that I've got will run off a 2S Lipo pack.  If it won't I've got a 5VDC fan coming that I'll run off the 5VDC battery eliminator circuit for the receiver, it's good for a 100mA load and all that it will be powering will be the receiver - no servos.  I'll just use the battery connection as my power switch for everything.

Next I need to figure out how to set this thing up in either my Unimat or my Sherline to mill away the extra plastic.  The stuff that's no longer needed and will just be in the way.


Good news - Bad news:

The Good news is that I got my battery pack Friday.  I disconnected everything, removing it from the skidsteer, and was able to bind the receiver to the transmitter.

The Bad news is that last night I was in a hurry to see this thing move so I put it back together really fast and plugged in the battery to see if I could actually make the treads move.  Somehow, one of the motor lead plugs and the battery lead plug got interchanged.  I'm pretty sure that it was that lazy good for nothing shop gnome that did the dirty deed.

Anyway, the magic smoke got let out of the TREX board.  Along with smelling REALLY-REALLY bad, once you let the magic smoke out of the electronics they just doesn't seem to function QUITE the same as before.  Once it quit glowing and cooled enough to touch, yes I saw a red glow so something on the board was actually glowing red, I looked it over but couldn't see any obvious damage - even though I knew there had to be a problem.

Since it already smelled like it was fried I decided I couldn't hurt the board much worse and hooked everything back up, this time making sure that motor leads went to motors and the battery lead went where it was supposed to go.  Amazingly enough it mostly ran.  The left track runs forward and reverse, while the right track runs forward - no reverse.

The TREX board was overkill for this application.  It will drive motors of up to 13 amps, my little 130 main drive motors are way under that - I'm guessing somewhere in the 0.5-1 amp range.  The TREX Jr. will drive motors of up to 2.5 amps, more than I need and it's 60% of the cost of a TREX - so I've got another TREX Jr. on its' way to me.

I also found out that I need to print a couple of shims so that I can raise the transmission mount a couple of mm.  The treads are a little on the loose side yet.


I printed out a mount for the TREX Jr. board last night.  While it might be about the same length and width as the TREX board, within a mm, it's got different mounting hole locations.  I really wanted to see the loader move last night, but then I remembered the magic smoke incident and thought "NOPE, not gonna do that again!"  Not sure if I'm going to get a chance to make it move tonight either.  Its' finally quit raining here, at least for today, and I've got to get the lawn mowed and the leaves picked up.

I also printed out and installed 3mm worth of 1mm shims under the motor/transmission mount to tighten the tracks.  They look better, but now it looks like I may need to move the transmission forward a couple of mm as the tracks are AWFULLY close to the upper part of the body.  Close as in touching when the raised part of the tracks go by.

As you can see in the "Couldn't resist" shot in Reply #2 there's not a lot of extra room anywhere on this machine.  That includes on the inside, there's a bulkhead that will probably interfere with the transmission if I try moving it forward.  I could take the shims out and move the track rollers, that I have yet to install, down a few mm.

That would tighten the tracks AND not interfere with any internal structures.  It'll give me a couple more mm of ground clearance too.  Good thing I haven't printed out BOTH sides of the track roller frames yet.  The problem with doing that is that it will effectively reduce the track length by about 1/3, making the machine unstable under load.  It would be more likely to rock forward and backward.  If you've ever watched a video of the "pros" dancing with a skidsteer while the back end of it is in the air you'll know that they are unstable enough already.

Maybe I'll just take some of the shims out and say "YUP, I've got loose tracks."


It's alive, IT'S ALIVE - sort of.  It's making a lot of the Nnnnn noises that the monster in "Young Frankenstein" made.  (That's pronounced Fronk-n-steen!!!)  It's moving about as well as the monster did when first animated too.

It moved forward - slowly, and it didn't want to move backward at all.  I thought that the problem was the tracks rubbing on the body, so I removed the 3mm of shims that I recently put in.  It seemed to help but is still moving slowly, in fits and jerks.  Tonight I'll take the tracks off and see how things work with no load.

The tracks still look awfully loose though, maybe it's a GOOD thing that I haven't removed the fake track rollers yet.  I may have to do something to turn the front roller into a track tensioner, just like on the real deal.  Where the track roller would have been is about where I'd need to put the track tensioner.

I'm wondering if maybe I just have a dead battery.  I don't have much experience with Lipo's. just the little 100mah 1S packs for my micro helicopter.  I'm more used to NiCads and NiMHD batteries.  When I checked the battery pack voltage I measured 7.64 volts across the cells.  I thought a Lipo's nominal voltage was 3.7 volts across the cells, so I thought that I was OK at that voltage?  Maybe I'm just farther down on the discharge curve than I thought.

Tonight I'm going to get the charger out, decode its' Chin-glish instructions, program it for a 2S Lipo and run a discharge-charge cycle on the battery pack.  It was after 11:00 when I quit last night and I did NOT want a repeat of the magic smoke incident while trying to charge the battery pack.  That might have let the magic smoke out of my house too!  Hopefully charging the battery will cure all my problems?


OK, progress update.  Been very busy at work so by the

I got the battery charged and didn't let the magic smoke out of anything.

I've taken the tracks off and put them back on a number of times, fixing a number of little issues along the way.  The only problem is it didn't help the speed much.  I realize this thing isn't a race car, but even at scale speed it should move a LITTLE faster.  I re-motored the transmission/gearbox quite a while back, went from the original 3VDC motors to 6VDC motors.  Right now, I'm reconsidering the wisdom of that move.

I've still got the original motors stashed someplace.  I might try putting them back in, overdriving them will help with the speed.  I might also do a little poking around on the Inter-web and see if I can find some higher RPM, 130 size brushed DC motors.

I also received the TREX Jr. board that I ordered.  Now I can see if I can fit everything into the available space in the cab without having to amputate anything from the designated driver.  So far he's sitting about a scale 4-6 inches higher than he should be, but he fits.  But that's without any cables plugged into the receiver or battery, waiting on a low profile battery harness.  He just might wind up minus part of his butt and getting cut off at the ankles.

If my work day doesn't run too long I'll try getting some up to date pictures.


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