Custom body, How do I achieve this, cheaply!

[Roog]

Dear RC car builders,

I have built an electrically driven custom car chassis, because it is a tethered race model it is narrow 135mm/5.3" wide and long 545mm/21.5".
As you can imagine I am struggling to find a suitable ready made body shell to put a skin over it.
Resigned to having to make a suitable body shell I am looking for a simple way to make one that doesn't require the use of a commercial vacuum forming rig.

I have drawn an example of how I think it might look, see below.

Because the main body is only 51mm wide I could make it narrower although the rear wheel would have to stick out, dragster like!

My ideas so far are:

• Fabricate out of thin modellers plywood on formers, like an upside down boat
• Fabricate from domestic plastic rectangular duct, subject to finding one which is the right cross section!
• Make a plug from foam sanded to shape, then coat with Resin and a couple of layers of glass fibre mat then dig the foam plug out.

Polished finish isn't my priority, although I accept that sanding to get a reasonable finish would be desirable before painting.

I would be really interested to hear of your ideas.

I could go with tin plate I suppose, I suspect this smaller clockwork model is made like this.

And yes my use of this design would require me to paint on the front wheels!

 

[WickedFog]

Back in the day, my friend's dad built the baddest RC car I have ever seen. It was a 1/4 scale Mustang funny car body on a pulling tractor chassis. He even built a 1/4 scale sled to pull behind it that he scaled down from actual blieprints he hot for one of the big named pulling sleds here in the US.

Anyway, he built a wooden body, then used it as a mold and laid fiberglass on it. It turned out really great.

Another suggestion, since your car will end up in a gazillion pieces if it crashes anyway is use styrene. It's super easy to work with and there are tons of YT vids on how to work with it.

Or, since your club may find a great need for custom bodies, it would be awesome if you were to buold your own vacuum form table to form your own lexan sheets over clay molds. I have looked into it, and have worked with vacuum tables before in the machining industry. @johnnydmd can give you some pointers as well, as he makes some killer lexan bodies.

 

[Chubaka]

Make a wood body and then vacuum form lexan, abs, or styrene. Need an oven to heat the plastic, a wood frame to hold and work the plastic, a 2x4 and pegboard airbox sealed with tape and a shop vac.

 

[tudordewolf]

Just looking at the shape, I think a 1L soda bottle cut in half lengthwise could be a good "base" for the shell, the bottom of the bottle forming the back of the car. Might be worth browsing the bottled water selection at your grocery store for good "donor" shapes.

Apart from that, I like the wood & formers idea - I think it would give you some of the best repair-ability and it feels to me like it would be the easiest to get started on & adjust your design as you go. You could even hand-shape a block of balsa for the nose pretty quickly, and use iron-on covering for the body, like an RC plane.

 

[johnnydmd]

Not sure what kind of bodies tether cars use, going that fast I wonder if lexan/poly would not just flap around insanely. Thinking fiberglass is the way to go.

@WickedFog I have been planning to rebuild my table for a year now, it's too small and the holes aren't really right (would use pegboard supported by joists instead). The metal car it's in is 24x36, so I'm going to probably build the box to fit just inside of that, 35x23. Lot of things I want to change too, like having the frame clamp better on the glass instead of having to drill holes around the edges for bolts to go through. Would also have guide posts at all four corners to ensure no twisting, and nice handles on the frame to lower it down the posts. It's a big project though, just haven't had time.

 

[Roog]

Thanks for all of your ideas, I am grateful.
I was hoping to avoid vacuum forming mainly because of the up front investment. The other guy in the club who makes wheel driven cars makes his own GRP bodies via traditional means, they are tough and quite heavy.

@johnnydmd Traditional bodies in the UK in the 1950's would have been tin plate or if you had money and the skill beaten from thin aluminum sheet. I quite like the idea of using tin plate, because it is easy to work and solder allowing details to be added and its traditional.
I have doubts about my ability to beat a decent shape out of a sheet of aluminum plus its is more difficult to solder.
Good point about very thin lexan, it might be flappy and troublesome at speed.
I haden't thought of making a foam body and you are absolutely right @WickedFog if this hits anything the body and chassis will be toast so the fragile foam body won't matter.
Similarly @tudordewolf I like repurposing things so a bottle might be an interesting starting point too.

I have seen one high speed RC car which used clay to create the plug, I liked that and would lend its self to vacuum forming.

 

[WickedFog]

Thanks for all of your ideas, I am grateful.
I was hoping to avoid vacuum forming mainly because of the up front investment. The other guy in the club who makes wheel driven cars makes his own GRP bodies via traditional means, they are tough and quite heavy.

@johnnydmd Traditional bodies in the UK in the 1950's would have been tin plate or if you had money and the skill beaten from thin aluminum sheet. I quite like the idea of using tin plate, because it is easy to work and solder allowing details to be added and its traditional.
I have doubts about my ability to beat a decent shape out of a sheet of aluminum plus its is more difficult to solder.
Good point about very thin lexan, it might be flappy and troublesome at speed.
I haden't thought of making a foam body and you are absolutely right @WickedFog if this hits anything the body and chassis will be toast so the fragile foam body won't matter.
Similarly @tudordewolf I like repurposing things so a bottle might be an interesting starting point too.

I have seen one high speed RC car which used clay to create the plug, I liked that and would lend its self to vacuum forming.

Then maybe, if it were me, I would look into styrene. Like I said, it's super easy to work with. It forms easily with boiling water or a hair dryer or heat gun. It can be glued easily and is easily repaired. Plus it will be a lot more rigid than lexan, depending on how thick the styrene sheet you use is. You could also weld in some ribs in any areas that might be a little floppy in the wind.

With your machinery and skillset, I would be dying to build a vacuum form table though, just because it would be useful for future projects

Regardless, I can't wait to see what you come up with.

 

[Roog]

Then maybe, if it were me, I would look into styrene. Like I said, it's super easy to work with. It forms easily with boiling water or a hair dryer or heat gun. It can be glued easily and is easily repaired. Plus it will be a lot more rigid than lexan, depending on how thick the styrene sheet you use is. You could also weld in some ribs in any areas that might be a little floppy in the wind.

With your machinery and skillset, I would be dying to build a vacuum form table though, just because it would be useful for future projects

Regardless, I can't wait to see what you come up with.

I Like your logic @WickedFog I have never tried to make a car body , wooden model boat hulls and superstructures but not car shells.

I think I might buy some foam and see how I get on, them I can decide whether GRP might be the next step.

 

[WickedFog]

One thing I will say about adding those front, fake wheels - if your car tilts at all and those make contact, really bad things are going to happen I would think.

And you can't be a Brit and tell me you don't love this

 

[Roog]

Ha ha I can think of worse, a Bond Minicar https://en.wikipedia.org/wiki/Bond_Minicar my old man had one in the early 1960’s

 

[WickedFog]

Ha ha I can think of worse, a Bond Minicar https://en.wikipedia.org/wiki/Bond_Minicar my old man had one in the early 1960’s

I love the Top Gear episode where Clarkson keeps rolling the Robin.

 

[Roog]

I love the Top Gear episode where Clarkson keeps rolling the Robin.

A bit like a Citroen 2CV they aren’t as bad as they look. I have been a passenger in a Reliant robin 3 wheeler whilst it wasn’t confidence inspiring it didn’t kill me either!

Faint praise “well it didn’t kill you!”

 

[tntpoof]

Roog. oood luck on having a teether car for speed. have you tested the tires curious on any results ?

 

[Roog]

Roog. oood luck on having a teether car for speed. have you tested the tires curious on any results ?

I tried my previous IC car, which runs on 4 of the same tires at the back end of last year in a rain down pour, the car skidded all over the place so it was a bit inconclusive, but the guy who showed me this way to make them has run them for years with reasonable results. The embedded fibres (Kevlar maybe?) and very thin steel wires in the conveyor belt rubber, apparently make them less susceptible to exploding.

They are very hard and don't offer much grip. I should grind them down to size but now that they are fitted to my car I might just run them as they are, they are surprisingly well balanced for such a rough finish, the first high speed runs will no doubt show up any weakness.

I'm not actually looking forward to running it. I enjoy designing and building but running them less so because I have to take time out of work to do this and it makes me very uneasy.

One thing I will say about adding those front, fake wheels - if your car tilts at all and those make contact, really bad things are going to happen I would think.

And you can't be a Brit and tell me you don't love this
View attachment 181782

You know, this body style is beginning to grow on me!

 

[WickedFog]

I tried my previous IC car, which runs on 4 of the same tires at the back end of last year in a rain down pour, the car skidded all over the place so it was a bit inconclusive, but the guy who showed me this way to make them has run them for years with reasonable results. The embedded fibres (Kevlar maybe?) and very thin steel wires in the conveyor belt rubber, apparently make them less susceptible to exploding.

They are very hard and don't offer much grip. I should grind them down to size but now that they are fitted to my car I might just run them as they are, they are surprisingly well balanced for such a rough finish, the first high speed runs will no doubt show up any weakness.

I'm not actually looking forward to running it. I enjoy designing and building but running them less so because I have to take time out of work to do this and it makes me very uneasy.


You know, this body style is beginning to grow on me!

I kinda figured in the beginning you were aiming for more of a 3 wheeled speed run car look.

 

[Roog]

I kinda figured in the beginning you were aiming for more of a 3 wheeled speed run car look.

This is true, although it scuppers the choice of body styles! There must be a car that looks good with three wheels surely?

 

[WickedFog]

You might just have to run it backwards for that

 

[Roog]

You might just have to run it backwards for that
View attachment 181821

Yes, it seems that most three wheelers run the other way around!

 

[Weezel]

Have you tried looking at a cowl for a tunnel boat? I didn't know if something like this cowl would work.
This is just an example. This picture is from a Zippkits boat.

 

[Roog]

Have you tried looking at a cowl for a tunnel boat? I didn't know if something like this cowl would work.
This is just an example. This picture is from a Zippkits boat.
View attachment 181915

Excellent spot @Weezel i like your thinking