Question about forming bends in styrene sheet

[Adam Baker]

Ok, on the GT One build I'm working on, I'm trying to replace the rear wheel wells b/c they werent shaped correctly.

One of the things wrong w/ the stock parts, is they dont have the correct curvature in them to conform to the tires.

I've been racking my brain for several weeks now, trying to figure out how to get the curve in a piece of sheet styrene. Last night I hit on a method for creating the curve. Using the blue foam insulation I have, I cut it to the shape needed using my hot wire cutter. I then taped the styrene to the foam and hit it good w/ a hair dryer. It helped some, but its still not quite to the shape I need yet.

This got me thinking about something I read awhile back in a modeling forum where a guy was doing something similar to me, he needed a curve in a thin piece of sheet styrene, and he said that if you put a bend in a piece of styrene, even w/ heat, and it sets, eventually the single peice of styrene will straighten out. However, if you put the bend in the styrene, and then glue two pieces of styrene together, it will hold the curve and wont straighten out.

Is this true? For my curved sections, I'm using .010"/.25mm thick styrene sheet, so gluing 2 pieces together wouldnt be too big a deal, as it wouldnt affect much the thickness I'm trying to achieve on the edge of the part.

 

[jknaus]

This would be a good one for Bob Letterman or Alex De Leon. Maybe if you check his motorcycle thread you might see something. Wish I knew the answer.
James

PS Randy might be another good guy to tap, he's an incredible scratch builder.

 

[Sherman 18]

There is a couple of ways to do it. You can rubber band the cut sheet to a tire and leave it over night.

Another is find a piece of PCV pipe (the size you need) and do the same thing. You might even be able to dunk it into hot water, I have never tried the hot water thing.

My favorite is cut a piece too long and then pull it over a knife hand to make it curl. (like curling a ribbon)

I know that if your glueing it to a flat surface (your half moon for the wheel well) the thicker the better. It is just easier.

Iron Mike may have done some wheel wells also, other than that James has is covered.

 

[Adam Baker]

Part of the problem is its not a true circle, its more of an elliptical shape, more akin to something like a french curve, it doesnt have a constant radius, so rubber banding it to a cylinder or one of the tires wouldnt work. I've got a lot of old prescription pill bottles on my desk that I use for various things, and those were the first things I looked at, but the shape just wasnt right, so I went looking for other things.

Right now i have 2 pieces of the styrene sheet taped to my piece of foam that I cut to shape, sitting in my dehydrator, w/ the temp selector turned up to about 130°, and I'll leave it there for awhile and then check it and see how it looks.

 

[Sherman 18]

You got to take pictures!

Hope it works for you, and I think I just might have learned a new trick from you.

 

[Adam Baker]

Oh yea, definitely gonna have pictures, haha.

 

[paddy]

I think you are right , a laminate will hold the curve, its how woodworkers do it. It will also be much stronger for the given thickness.
Let us know how you get on.

You can see the idea here in wood

http://www.finewoodworking.com/SkillsAndTechniques/SkillsAndTechniquesAllAbout.aspx?id=2962

 

[willem]

Hi Adam,

I dont have much experience myself, but here is a link to a gifted scratch-builder over here.

http://www.twenot-forums.nl/viewtopic.php?f=25&t=25946

He was asked the same question.
Answer was that he bends the sheets with his fingers repeatedly, meanwhile rubbing the bend to make it warm/bendable.
This way he claims to do any shape ! Look at the vehicle.

Succes, willem

 

[Bagge]

the sandwich way should work i think otherwise just heat it in warm water for a while then it should stay in place
//Mats

 

[chukw]

I would find a cylinder or disc the same size (mostly) as the tire or wheel well. Cut a strip of styrene to the proper width and a little longer than you need. Wrap it around the form and secure it with a heavy rubber band and some string or thread. Dunk it in water that has just been taken off the boil for 10 seconds or so. Let it cool and viola! Curved plastic that will stay curved.

 

[moon puppy]

How thick is it going to be? Will the fender have like a lip on either side?

 

[Adam Baker]

I think I've managed to get 2 of 'em made. I took the 2 pieces and taped them to my foam form and put it in my dehydrator at 140° and left it there for about 4 hrs. After taking it out, I put it in the refrigerator for about 10 minutes, and they seem to be formed about what I want. It didnt hold 100% to the shape of my form, but its pretty close.

I think I may go ahead & glue the 2 pieces together, to help hold the shape, and then carefully sand them down to have the thinner top edge that I'm trying to replicate.

It wont have any kind of lip on it, the finished wall is pretty thin, which is the look I'm attempting to replicate.