Coroplast thermoforming

[Otto]

Has anybody tried heating Coroplast to shape it, such as creating permanent bumps or depressions, or gentle curvature at the edges?

If this works, it would be very useful adapting a flat piece of Coro to fit over the occasional underbody protrusion, or making fairings for the wheels, etc..

It would also be very handy for a shaped pickup truck bed cover.

Thoughts?

[Frank Lee]

I've formed it with a heat gun. Of course simple 2-D curves are a snap; compound curves can be done as well. It is very easy to overdo it with the heat and cause unwanted melting. The ribbed internal structure of coroplast collapses if too severe angles are attempted- that might be no problem though. The concave side of curves collapses/wrinkles as well, so if you are concerned about the aesthetics of the part try to only have the conves surfaces visible as the concave ones will look shriveled.

Overall it is a very easy material to form and work with but the ribbing causes some aesthetic limitations.

[Varn]

I agree with my twin frank lee. (that is if I lost 30 pounds and I lost 30 years and he grew a decent beard )
Coroplast can be heated on the inside of the bend with a heat gun. The side that you heat gets funky but once it cools the structure becomes much more rigid. It takes practice to do it right. Keep the heat gun moving over the entire area that you want to flex. Gentle bends are sometimes the most difficult. Practice on a scrap or two first.

Remember this is becoming election season. Do your civic duty and pick up as many 4x8 election signs as you can. You have to go out on the evening of the election.

[Otto]

Thanks, guys, that's what I was hoping to learn.

This will come in handy at belly pan time, when a low hanging widget would otherwise prevent use of flat sheet of Coroplast, or when I want to make an AR-5 type of vent to the slipstream of engine cooling air. In such cases, heating would allow the Coroplast to have a teardrop-shaped blister at the low hanging widget, and gently curl up to make a nice exit pathway for the hot air.

BTW, is there a good, durable adhesive for Coroplast?

[skyl4rk]

I have folded the coroplast using heat, with the purpose of doubling the edge for strength and to make it easier to fasten to. I took a metal straight edge, clamped it down along the coroplast at the bend, and ran a propane torch along the bend area, then quickly grabbed the coroplast and bent it. Then flamed the other side a bit to make the coroplast relax and keep the bend.

I think you could make a bump in the middle of the coroplast. Cut a hole in a piece of plywood in the right shape. Set the coroplast on the plywood. Make a plug with rounded edges, smaller than the hole in the plywood, and make it so you can add weight. Put the plug with weight on the coroplast over the hole, and from underneath, start flaming the coroplast. It will probably get wavy and buckle, but I think it would work and would be permanent if you let it cool before removing the plug and weight. You might want to make a stop so that the plug doesn't go all the way through.

Coroplast could probably be vacuum formed, within limits. The corrugation reduces the ability to change the shape, but some changes could be made.

[Otto]

Originally Posted by skyl4rk

I have folded the coroplast using heat, with the purpose of doubling the edge for strength and to make it easier to fasten to. I took a metal straight edge, clamped it down along the coroplast at the bend, and ran a propane torch along the bend area, then quickly grabbed the coroplast and bent it. Then flamed the other side a bit to make the coroplast relax and keep the bend.

I think you could make a bump in the middle of the coroplast. Cut a hole in a piece of plywood in the right shape. Set the coroplast on the plywood. Make a plug with rounded edges, smaller than the hole in the plywood, and make it so you can add weight. Put the plug with weight on the coroplast over the hole, and from underneath, start flaming the coroplast. It will probably get wavy and buckle, but I think it would work and would be permanent if you let it cool before removing the plug and weight. You might want to make a stop so that the plug doesn't go all the way through.

Coroplast could probably be vacuum formed, within limits. The corrugation reduces the ability to change the shape, but some changes could be made.

That's what I was hoping to hear: Suppose I could otherwise attach Coro to existing fix points on the bottom of my Ford Econoline van, but for a couple or widgets protruding below a horizontal plane formed by the vehicle's rocker panels and other structural geometry. By making a plywood template of teardrop shape and putting it at the proper places on the Coroplast, I could make thermoformed aerodynamic blisters in the sheet, so it bulges down far enough to clear the pesky widgets, but is still basically flat to take advantage of the van's rocker panels and other co-planar attach points.

Such localized heat forming would also be handy for making flat nose undertrays into wheel fairings--flat in the middle but gently drooping blisters at sides to fair the air past wheels. Some of the baby Benz cars have this sort of fairing, but we could do it on the cheap.