M548 tracked cargo carrier - RC 1:10

[Tanker929]

My next project is a scale 1:10 RC M548 tracked cargo carrier. I am making this model into a replica of one of the M548’s that the Bovington tank museum uses to drive visitors around a track (“the arena”). I participated in a ride myself a couple of weeks ago so this model is a nice memento for that visit. And somebody already made a 3D print design for this vehicle, that helps

https://cults3d.com/en/3d-model/game/pr ... ourhobby3d It's listed in the "3D models to print" topic. Check out the assembly guide on this page btw.

The design is very detailed and the entire build is challenging, not in the least because of the number of parts involved and because of the build complexity. As the designer puts it:

What are you dealing with? The main dimensions of the model are 570 x 269 x 293mm. Total assembled model weights 5.05 kg, and you will need 3.6 kg of filament. 118 hours printing time!
752 pieces are waiting for you to assemble them using over 1095 nuts and bolts. Top speed of 12.7 km/h with 540 55T Brushed Motors and 2S Lipo.

So I've been printing for 2 weeks now. That's 95% of the pieces printed. The entire RC part is not even on the table.



For reference: that's my glasses in the middle of the photo



For me it is also challenging on the RC side since I have very limited experience, save for the CyberBrick projects I did before. I presume “540 55T Brushed Motors and 2S Lipo” sounds familiar to most of you but for me it means learning curve ahead. And an impressive AliExpress shopping list.

Fortunately the design is high quality, not only in accuracy and detail (that’s the 3D modelling aspect) but also in translating the model into ready to print build files – the 3D printing aspect. The build guide is well written and quite clear.



I'll be adding custom decals I will make myself to make the model into the nr. 4 vehicle used in Bovington. To make it even more accurate I could add passenger seats in the back, just like in the real one. However, I didn’t think to take detailed photos of the vehicle interior as I didn’t yet have the idea to build this model at the time of my visit. Mhhh … next time

[Herr Dr. Professor]

The photos of the printed parts spread out over the table amazes me. I will enjoy watching your build progress more and more.

[Tanker929]

Today the motors arrived, the final pieces of the puzzle. I had no idea they would be so big & heavy, compared to the ones I have been tinkering with so far. One of the CyberBrick motors in the foreground for comparison.





That kinda explains the "pretty dynamic" promo videos I guess:

https://www.youtube.com/watch?v=3agVXcGssk0

https://www.youtube.com/watch?v=Bm7-XCY8gZA

I'm starting to wonder if I used the right filament for the axles, gearbox components etc. If I remember correctly I used both PETG and the new Bambu "PLA Tough+". ABS / ASA would have been better I guess. We'll see ...

[Herr Dr. Professor]

I realize that this is not a large AFV, but is a 2S LiPo going to be enough for it? I am curious, because I have so much to learn even after 20 years of RC AFVs.

[Tanker929]

*You* have much to learn you say?

I have no idea whether the battery will be strong enough. I'm pretty much painting by numbers here. I had a 2 hour conversation with Copilot yesterday just to learn about battery connector types, balanced charging and so on. The manual has one page on printing & building the gearbox, 2 pages on the motor mounts and rigid flanges - whatever those are. And for the rest, the entire electronics part, just this:



I'll be coming back with questions. Lots of questions

[Herr Dr. Professor]

Your situation doesn't seem all so different from mine. Fiddling with the electronics is still challenging to me. I have one or two some go up in smoke--fortunately at not great expense.

Here are a few videos that have helped me:

On two-motor control: https://www.youtube.com/watch?v=uQIGb8VzX08 and https://www.youtube.com/watch?v=sIgX9P8l8kw

On Lithium Polymer batteries: https://www.rogershobbycenter.com/lipoguide/

On charging batteries: https://www.youtube.com/watch?v=dGiInCMNq9w

[Stormbringer]

Reason you remove the red wire from the esc is each esc has a bec (battery elimination circuit) so you dont have to power the receiver with other batteries
if your esc has a bec of say 5A and reciever has a current limit of say 6A if red wire from 1 esc not removed it can give 10 A so if something shorts or a servo stalls it can fry receiver
sorry if you already know this but just thought mention it
Ohh you dont need to cut the wire you can remove it from the plug and tape it back out way handy for future use

[Herr Dr. Professor]

Sorry to butt in here, Tanker929: I am learning, too.
Alan a.k.a. Stormbringer: Is there a way to add (as in the schematic Tanker929 gives above) a steering servo, as used for a half track?

[Stormbringer]

It would depend on how many channels your receiver has (in my ships its usually at least a 4 channel receiver)
I guessing your wanting the front wheels steerable ?
each of the esc's will have their own receiver channel and the steering servo will go on another channel
I use a similar setup in my scale rc ships with twin screws and use the built in mixer on my aircraft transmitter to mix the 2 esc channels
bit like heng long do putting it on 1 stick for forward,reverse and turn and the other stick would be rudder or steering servo
is this what your asking mate ?

[Tanker929]

Not sure I'm following here: a half track actually has front wheels - this model doesn't. I would imagine steering a fully tracked vehicle is all about how you map the joystick controls to the motors driving the drive sprockets?

First things first: the bill of materials specifies the motors and speed controllers but not the receiver. Any suggestions here?