Thought experiment: scratchbuilding an RC car in my garage

[markbt73]

This is something I have been thinking about for a couple of years now, brought on by studying the designs of some of the simple old on-road cars from RC's early days. There was no CAD back then, no 3D printing, injection-molding was (and is) prohibitively expensive for small quantities, but still dozens of companies offered car kits. One has to assume that all of these started as somebody making a prototype by hand in their garage.

Which got me thinking: how hard would that be? Could I do it with the tools and skills I have, and materials I can easily get?

I'm imagining a simple 1/12 scale electric on-roader, something similar in design to an Associated RC12E or the early Tamiya cars. Direct-drive, little or no suspension, simple shapes. Cars like that are remarkably similar in shape, and very simple in design.

Chassis is no problem, just a flat piece of fiberglass sheet cut into the proper shape. Maybe with an upper deck to support the radio gear.

For the rear, I'd use two upright chunks of thick plastic for axle/motor supports, bolted together with some more fiberglass parts to make a rear pod. Axle would have no diff; a lot of the early cars didn't, and the little Mardave 1/12 scalers still don't. The pinion and spur would have to come from my spare parts stash; obviously I can't make those.

Front end is a little trickier; I'm imagining a pair of axle blocks mounted on kingpins, maybe on a separate plate a la Bolink. No need for suspension apart from parts flex, really.

The body would be interesting. Have to make a vacuum-forming machine, carve a wooden buck into shape, and probably ruin several sheets of Lexan (or styrene) getting the technique down. But it would be fun to try.

Wheels and tires: No idea. I have a half-baked vision involving a hole saw, some thick plastic for disc wheels, and plumbing pipe for rims, but I'm not sure it would work. And I don't know what kind of foam to use for tires. But even if I had to buy rolling stock, that's OK too, I guess. If I could make my own wheels, then brass tubing bushings wouldn't be too hard to do.

Running gear: Obviously I can't make a motor or radio, but I think I can make a simple mechanical speed control. Just need a rheostat and some scraps of copper sheet.

Not sure if I'll ever have time to try this, but it's a fun thought to throw around...

[yogi-bear]

cool thread, and with some of the right tools I think not too hard, well certainly not impossible. I would say to make it easier, you would need at least a drill press and lathe (a lathe is on my to buy list ). With these two, you should be able to machine most parts, in fact I found a thread a couple of years ago where a guy made a 1/4 scale V8 motor, full functional.

Body wise, you could also become a plastic-card magician like Johnny Retro (there seems no limit!) or back in the day many car shells where made from fibreglass, but that is heavy.

Tire wise, I would suggest either hard foam, solid rubber, on coincidently I was reading an early 1970's rc guide book and they mention using cross sections of a bicycle tube to get the final layer of tire on a wheel.

Most of your suspension can be cut from aluminium block or (going off this guide book) lots of piano wire with a bit of soldering for the swing arms.

As for electronics, if you are mega keen, there are plans to make your own circuits, but not for the newbie, and you would still need some specialised microchips.

Personally this is more where I want to go with rc cars, albeit with a little more machinery that they had in the past. I have a small cnc machine, so that is what I am trying to use to make my Volvo Body (just awaiting for some new pieces to arrive so I can make some deeper cuts). This machine I will upgrade, then I can make some chassis sections for a Mauri Big Bear.

Looking forward to see what other people post

[markbt73]

Oh yeah, forgot to mention the tools I have on hand: drill press, Dremel, scroll saw, tap and die set (metric), basic woodworking/metalworking hand tools. The challenge, I think, would lie in not using any computer assistance: no CAD, no CNC, no 3D printing, nothing like that. I have enough drafting skills to pull off the design (I think), and I'm no stranger to making parts by hand.

[MadInventor]

Oh yeah, forgot to mention the tools I have on hand: drill press, Dremel, scroll saw, tap and die set (metric), basic woodworking/metalworking hand tools. The challenge, I think, would lie in not using any computer assistance: no CAD, no CNC, no 3D printing, nothing like that. I have enough drafting skills to pull off the design (I think), and I'm no stranger to making parts by hand.

I make do with no CNC, no CAD, or no 3d printing. All my designing is done literally on the back of a cornflake packet. I've got the advantage of a mill and a lathe, but you can still do a lot with a drill press if the patience is there to accurately position the parts before drilling, and it was what I started off using to make parts for my clodbuster. You can make the drill press lot more flexible by getting a cheap cross vice, which will allow you to more accurately drill hole patterns. I would say that a cheap Chinese digital caliper is an essential tool for accurate marking out.

I would say it should be eminently possible to build a simple RC car with the tools you have

[LongRat]

Of course you can do it and I have made two complete RC cars from scratch with a lathe an mill manually like this. Then the engineering of the machines themselves became a hobby for me and I built several CNC milling machines for the purpose of making better RC cars. The ability to make pretty much anything you can conceive of is eye opening and totally liberating. Beware hobby overload in this field!

[speedy_w_beans]

markbt73, take a look at the RJ Speed kits. You could make a car similar to the Sport 3.2, LTO, or even the Digger quite easily with a few sheets of FRP, some aluminum L-channel, and fasteners/hardware from McMaster-Carr. Just download the instructions and parts diagrams, and you'll see what I mean.

[markbt73]

Oh, I built about a dozen of those back in the Bolink days. In fact, I used to race a Bolink 91 Sport, before I sprung for a 10L. I know them well.

Now that I think about it, maybe a pan car is too simple; perhaps I should be thinking in terms of full suspension...?

[Saito2]

Great idea! I've often dreamed of scratch building. If you watch the old RC10 Winning Edge video with Roger Curtis, you realize just how much was/can be hand made. The prototype aluminum tub was hand hammered over a wooden buck. Nylon arms and such were often fashioned with a Dremel. I remember checking out a book way back in junior high that showed you how to make and RC tractor trailer truck. Radio gear, wheels etc. were all borrowed from the model RC airplane world which was booming before cars became prevalent.

[beefmuffin]

The BEEF man gets exhausted just thinking about it! Well... I guess the BEEF man was already exhausted. But STILL!

[emory70]

I've thought off and on for over 15 years about building a car from scratch. But I have no issue with using factory made parts where it will make the job easier.

One of my myriad projects is an RJ Speed Digger. I really want to put a real front suspension on it, but the right simple idea has eluded me so far. This is it mocked up, but I need to come up with a mount that I like.