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Old 04-22-2021, 05:28 PM
dremu dremu is offline
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Default Re: 1:10 M1070 and M1000 HETS

I've seen several M1070 builds, but not so many M1000 trailers. Not only is there not need if you don't have an Abrams or other crazy huge thing to pull, they're a complicated setup.

Five axle rows, with independent bogies each side, each bogie having four wheels. The really tricky part is that all of the bogies steer, but at varying angles. The fronts turn a little, the next ones back turn more, all the way to the rears turning a lot, and the outer ones turn a bit more than the inners. Here's a 1:1 in action

https://www.youtube.com/watch?v=f7jHBH_zrDs

No way I was gonna do that purely mechanically, especially when doing it electronically means that turning ratios can be changed at the push of a button. As always, draw the thing up first in CAD (donno what the red block is, musta been testing something)





Arduino (top), servo controller (middle), and a power distro board down by the big capacitor at the bottom. Had some issues getting enough current to run all the stuff (servos, lighting, outrigger legs), so there's a separate lager-gauge power wire in addition to the smaller trailer signal wire. The M1070 has matching plugs for both, but if it's being pulled by a smaller truck, a battery directly connects to the trailer power.

Also, that many servos create some serious spikes on the 6V side when turned quickly and/or under load, like enough that they'd brown out the Arduino Thus the big filter capacitor for the Arduino (and servo controller board and the LED string).

This one is more mixed-media than most of my builds. The trailer frame is welded steel



Bare steel, being clamped and tacked, and the two white plastic things are 3D printed servo mounts to keep all the crossmembers aligned.



and the bed is wood of various thicknesses



That's the bed and the frame. Doesn't look like much yet!



there with the PLS on it. When I was working on the trailer, often had to borrow a second pair of hands to flip it over as it's so unwieldy. (Why did I pick 1:10 again? Just so my builds match? Ugh!)



Doing individual pieces of different thicknesses of wood allowed me to do the center rib with the pockets on each side, without having to try and route the pockets or the like. Also means it's less prone to warping as it's not one piece. (It's also glued-and-screwed, using Tite-Bond glue, which I found to be downright nuclear in its adhesion.)

Hard to see, but the neck is an engineering challenge as well. It's a number of printed pieces, glued together (again, bit surprised it can handle the load placed on it.) It's hinged at the base (lower white piece with two holes, the left/lower hole being the hinge) and then a short shock absorber acts as a dampener (right/upper hole, shock goes down underneath.) Filled the shocks up with fluid so they're pretty tight, just enough travel to hold the neck in place with a bit of give.



The bogies mount on 608ZZ bearings (I love those things as they're cheap and mount nicely on an M8 bolt or rod), and then there's a servo inboard to turn them, on a 3D printed mount.



Again with the cat scans. That second one was when I was doing turn testing, and she just HAD to check out what all the noise was.

Each bogie has an M8 threaded rod axle, and then a very stiff vertical spring. They have nice flat ends and fit into rings printed into the upper and lower bogey halves. As previously mentioned, I use pool noodles for tire foams. However, I discovered after the fact that when loaded, the trailer tends to pop the tires off the rim, so apparently I should have cut these rather wider. Sigh.



It's very hard to get motivated to redo 42 wheel-foam-tire setups.

Though you don't really see them, the bogies are actually pretty close to the 1:1, both in appearance and function. The upper and lower halves are hinged on a piece of 3mm brass rod.



The wheels also have 608 bearings. Each "dually" is actually printed as one, with the inner face being solid save the cutout for the inner bearing. The outer face has faux lugs printed, the joys of a dual-extruder printer. There's a washer on the inner face to space the bearing out from the bogie just a smidge, gives the tire clearance, and then nylocks on the outer faces/bearings to actually hold the wheels on.



A small spring keeps the lower half from dropping and the blue spring from falling out when it's not held in place by gravity.



Each servo has a steering stop to prevent the bogie from turning too far and getting locked up. To the right is an M8 bolt holding the upper bogie to the frame via the 608 bearing; the ring outside it holds the big suspension spring in place. The lower bogie has a match ring.



The stop has two M4 threaded inserts; adjust via turning the bolt and lock in place with the nut.

Front and rear have outrigger feet, vaguely similar to the 1:1. Unlike the 1:1, they're not independently adjustable; mine only do front and rear, but I've found that's enough. When hooking up the fifth wheel, I raise the rear of the trailer, which puts just a smidge of pressure on the kingpin, enough to latch it.

Here's the front, sorry for the errant thumb



and the rears



Aluminum channel down the center keeps the servo and outrigger actuator wiring mostly in check. The lighting is strung around the outside; they're the "NeoPixel" style, so are point-to-point.



Another design compromise is that the feet stick down too far and get caught up when the trailer is on any real incline. However, these are the shortest actuators I could get in that strength rating, and even the next ones down wouldn't fit much better.

The rear ramps hinge on 3mm brass rod, and are width-adjustable for the Abrams, or for narrower loads like trucks. They're not counter-spring loaded or powered or anything, as I just couldn't find any clever way to do any of that in the space available. Instead, there's those chain-binders made out of left over bits, small turnbuckles, chain and hooks, threaded rod, and vacuum caps.

Another thing I'd change if doing over again is the length of the ramps. These are made to be close to the 1:1, but are a bit steep for the Abrams (it teeters, and then when it comes down, the trailer bangs a bit and lifts the truck up just a smidge.) It's better loading the tank backwards, which IIRC is how the 1:1's are done, but it's still hairy.



And there it is without the tank. Hard to see, but there's a pulley at the back that just about matches the 1:1 sheave, rescued from my junk drawer. I think it used to hold up clothesline, but slightly justifies my hardware hoarding habit

Last edited by dremu; 04-25-2021 at 09:11 PM.
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