Anyone use the thermoform technique?

[philo426]

Recently received this incomplete diecast Hubley 32 Chevy in trade.Missing the trunk lid so I cut a piece of sheet styrene slightly oversized and clamped it to obtain the correct curvature.The plan is to immerse it in boiling water and allow it to cool.   

[MrObsessive]

That sounds like an interesting technique that should work, but there's a caveat.

When it comes time to paint, I seriously recommend washing the body parts in very lukewarm water as opposed to hot. You've bent the plastic to shape, but it still has its "memory" and as soon as any type of heat is applied to it, it'll want to go back to its original shape which was straight.

The same can apply to resin too.........that can be fixed with some heat, but I strongly advise against washing the parts in hot water, or using a dehydrator to dry the paint.

One thing that can also help in keeping the shape of that trunk lid is to perhaps epoxy some brass strips on the inside perimeter of it, which will help reinforce it against any possible deformation.

Hope this helps, and keep us posted how it turns out!

[philo426]

Okay thanks for the tips!

[Ace-Garageguy]

Bill Geary has a point, but there are some other factors to consider...which I know from personal experience.

Styrene (and many other plastics) have what's known as a "glass transition temperature" or T_g.

This is the temperature above which the plastic in question will be permanently deformed.

For typical styrene, this occurs at about 100C, or 212F, which is boiling water. If you get your plastic that hot, any "memory" will be erased.

Also, a lot of styrene sheet, tube, and strip stock is in a "non-tempered" state. That simply means it's "floppier" than it will be if you bring it to its T_g and allow it to cool again.

Fastening a sheet of styrene stock to a form, as you have here, and dipping it in boiling water for just a few seconds, will usually result in the new part permanently holding the new shape. The new part will be "tempered", and not as flexible as it was before heating and cooling.

I use this technique frequently for scratch-building things like trans tunnels, and getting smooth, permanent bends on sections of roll-cage material.

Just be careful you don't leave it in the water too long. You don't want the kit part to warm through and deform as well.

 

 

[philo426]

Okay!Thanks!

[philo426]

ok it seems to have worked,dunked it into the boiling water for for 20 count.I glued the rumble seat to ensure it retains its shape.Very cool!  

[philo426]

Came out pretty well!