Slot Car Material Help

[osubound]

For a competition we are building a slot car, and we are building ours in a typical drag/CO2 car fasion. We need the body to be light as possible yet strong enough to survive the crash into the netting at the end of the track (shouldnt be too hard of an impact)
Our current idea is to carve the body out of styrofoam and coat it with a fiberglass or hard enamel for strength.

Any suggestions on the shell/coating (needs to be easily available and decently cost efficient)

New body material ideas are welcome too

 

[AlanD]

For a one off shell, this may make you laugh, but make a mold of the shape you want and then make the shell out of paper mache'. It should end up lighter, just as strong and easier to build than the equivalent in fibreglass.

 

[MintJulep]

I second the make a mold idea. Why bother with a core when you can have only the shell.

How big is this thing, and how strong does it need to be? You could use an epoxy or polyester resin only, with no fibers at all. This would give you essentially a plastic part.

Pretty much the whole universe of textiles is available if you need a cloth in the shell to increase strength.

Fiber glass is heavy. Carbon fiber is lighter, and way more cool. Kevlar is cool too. Any number or polysomethings would probably work.

 

[osubound]

It's ~12in long by ~3in wide, and they really did not specify how strong it needs to be, just that they did not have a great stopping system, just some sort of netting contraption, probably some sort of runway.

The mache idea sounds great, i never thought of that.
Thanks for your help so far.

 

[btrueblood]

A few more ideas for ya:

Buy a few cans of polyurethane foam (sold at most hardware stores as insulating/caulking foam), and squirt it into a mold. This stuff is cheap (we use it in our packaging machine here at work), so you could mold several bodies, and replace them as they become too damaged.

Mold outer shell and inner shell using paper mache' as above, then fill between them using urethane foam - the resulting "sandwich" will be much stronger than any of the elements it's made up of.

If you want a smooth shell surface, buy some thin ABS or ABS/PVC or styrene blend sheet material. Thermoform the sheet material into a female mold carved in a wood block. Thermo-forming is pretty simple (heat the sheet in an oven to the plastic temperature, clamp it to the open side of the mold, apply vacuum to the mold cavity and the sheet "sucks down" into the cavity. Allow to cool, and voila.

 

[EdStainless]

Thermoformed ABS is how the real ones are made.

We used to buy one that we liked and then waxed it with silicone wax. Then mold over it with polyester fabric (lining material) soaked in a polyester resin. Let it cure and pop it off, and mold another. They are usually too thin, so you have to add some internal reinforcement at mounting points, but they are light.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[AlanD]

Don't underestimate the strength of paper mache'. Helmets made from paper mache' were used as hard hats by cavers and climbers before plastic ones were readily available.

 

[btrueblood]

AlanD - I agree. And using a more modern formulation of epoxy resin with chopped cellulose fibers can give some really astounding results.

 

[SMF1964]

liquid/fiberglas patch material sold in most autobody stores could work for a surface as well, but again you have to start with a mold.