Reshaping plastic

KariFS wrote:How about heating it more while it is still clamped? Maybe you need to ”over-bend” it slightly to compensate the ”bounce-back” of the plastic  

This is an interesting topic for me too, since the fin of my P-40 is bent, probably because of being stored upside down and/or under a pile of stuff.

I tried that Kari heating with it clamped.  Tried the "over bend" too but because I don't have a third arm it went nowhere.  

Heat "probably" caused the distortion in the first place softening the plastic and causing the molecules to expand.  But, wouldn't heating it again cause the same expansion multiplying the problem and resulting in even more distortion. The theory is more heat with applied pressure compresses the molecules back into place.  

But, if heat causes expansion and cold causes contraction.....I'm about to clamp the thing on a flat board and pop it into the freezer.  

Someone here. I think it's Jim or maybe Roddie is proficient in molding plastic canopies over a mold, maybe they know the secret of how to get them back into place.

Bob

Thanks everybody. When all else fails I will try the steam/hot water route.

It's presently clamped on a flat board, checked it this afternoon and it seems to be coming out. At the very least, it's a whole lot better.

Thinking all-over olive drab and proper decals.




Bob

Mark Boesen wrote:Problem with a heat gun is it can get too hot and the plastic will suddenly melt without any indication, its a small window, lol, i know...

I agree, and that's my fear not just with this $7.99 (went back and checked the actual ebay price) Testors P-51 but with my Aurora models too @ $100+.  Large chance to make it worse than it already is.  

I have a couple of dual range heat guns and use them very carefully.  Problem is, they spread the heat out over a large area when I need concentrated heat in a small area for a short period of time.  I have a butane torch that does that, but imagine the consequences of using it on plastic.  

Balsa is so much easier to work with.  

I had a difficult time removing the side decals.  Testors did a good job with them.  The side decals had three layers, a base of metal foil, the decal and a clear plastic cover.   Simple Green removed most of the silver paint on the model but getting it out of the highly detailed (simulated rivets) areas was a pain.  

I had some paint remover, directions say "Do not use on plastic" so naturally I had to try it.  It took off the paint and seemed to do the plastic no harm.  Same for the decals but it took a lot longer.  Later my son reminded me that I could have used Easy-Off oven cleaner which does not harm plastic.  I did rinse it well right after using the paint remover.  

Thanks Chancey, Brake fluid works but it takes awhile.  I have lots of experience with non-synthetics eating away at the paint around my MG and others master brake cylinders.    Does a great job at that.

Eric It seems to me that the plastic used in these model cars and airplanes is some sort of high density polyethylene with melting temperatures of around 250 to 350 degrees F.  I wouldn't think it was acrylic.  No way would I heat it that high.  

Heat gun moderately applied then clamped over and over is showing promise.