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With the long weekend, had a little time to dive into a project I have wanted to do since I was a teenager.... RC Sprint Car!

Got the tub first mocked up in cardstock, and then 30g sheet metal so that the suspension and powertrain could be mounted for fitment. The sheet metal is a PITA to work with, and difficult to make small changes to, which was the whole point of it, but none the less, the basic design for the tub is complete (I think?). I will make a few more changes, and hopefully be cutting and bending some 16g aluminum tomorrow.

This is awesome! I love RC10-based sprint cars.

So I bought a big enough piece of aluminum for two tubs.

1st one, I didn't like the radius of the bends, and then I made a couple of mistakes, and it went into the bin.

After jerry-rigging my el-cheapo brake, I got it to make acceptable bends, and went ahead and made my second tub.

This would be the moment I realized I bent it upside down and the sides are reversed.

Dont ya hate it when that happens!! Its a great project, love the modern sprint tires too. Gonna be great!

joelwhite wrote: ↑Tue Jul 06, 2021 5:16 pm Dont ya hate it when that happens!!

I do, but the great thing about working on these vehicles as a hobby is, oh well, screwed up, do it better next time.

TBH, I had flaws in that design anyway, so the next one will be better. But then again, that one will have flaws also, and then the next, but oh well. Whichever one seems to be symmetrical and everything mounts semi-straight to it will be the one I go with. I went by the metal store today and they had a "drop or dragged" piece of .063 5052 with my name on it, so back in business to take another shot tomorrow. The piece is 14"x48", so I have to get it right by the eighth try!

Biggest change in design is that I am going to go brushless, which I hate to do on a RC10 based build, but I hate how close an open end ball of a brushed 540 is to the aluminum tub. I can get a BL motor that is just slightly stubbier, and has insulated wires coming out from the side, and that way I can just eliminate the whole/hole opening in the side of the tub. I hate to do it, and maybe I find the perfect brushed motor in the future, but for now, BL is the plan.

Starting to look at other systems during the down time on the tub. I printed a servo mount so that all of the front tub screws are used as they should be, but a simple servo with generic saver can be used. This will save space in the tub, as it has been drastically reduced. Wide arms bring the track width out to close to where it needs to be.

Got back on track and have the tub to where I think I want it. I tossed the redesign to BL, and just cut a big ol' hole in the side and will run a brushed open end ball motor. It is close and sketchy, but I will work out the details later. It also makes part of the tub super thin and weakens the whole thing a little, but later there will be enough support throughout the rig to stiffen it all up enough I think.

I originally thought getting the tub complete on this project would be 50% of the job, but now I am thinking it is 15-20%. There is so much left to figure out!

I ended up moving the rear arms back a bit which increases my WB to 9.375", which is outside of the 90" rule at most 1:1 tracks, which bums me out a bit, but it'll be fine.

Oh well, as it stands tonight:

Built a new bulkhead / battery hold down to act kinda as the original did. The aluminum trans plate screws to it to add rigidity to the whole thing. With that in place, it is time to start bending some tube!

Not much progress lately as I am neck deep in real work, but a little got done recently. I started bending some cage tubing, but got distracted by trying to clean up the inside of the tub some.

I told myself as soon as I started thinking about this build that I did not want the typical screw on headers that I see on too many sprint car builds. I wanted the tubes to go into the chassis and, well, attached to something, maybe something like an engine. The original plan was to bend my own aluminum or steel tubes, but after a few minutes of that, nope. Those radii are way too tight, and at 90* to each other, and yea, ain't gonna happen. I decided to print the main part of the headers, and then the plastic tubes will end up in an aluminum collector from that point until the end. Not the right way to go about it, but the right way for now. When said and done, I think it will look great.

The tub will end up with two basic printed covers. The rear cover acts a support attaching to the rear bulkhead, the trans, and the mid bulkhead, while covering the spur gear. Currently it is just a simple plate, but it will end up changing as I figure out the interior / driver later. The front cover will be easily removable and will hold the engine / headers, and cover the battery pack and RX.