19 replies to this topic

[Lovefordgalaxie]

I think everibody had this problem once or twice. You bring a new kit home, and when you do open the box, you find out that ther is a clear part broken.
That happened to me with a AMT '58 edsel prepaint. All parts were inside this little bags, and the windshield sat there, happy divided in two

Well, like I didn't want to butcher a Edsel kit to fix my prepaint, I decided to try a little trick I learned card modeling: heat forming a clear part with actual curves, just like the original kit part.
You only need to glue the original part back together (it will be the template for the new one), a small or mini torch, and a soft drink bottle, those made from PET plastic.

First, it's important to know that this only works with PET (polyethylene terephthalate) plastic bottles. This plastic shrinks when heated, so you have to direct the heat to the area around the mold, and over the mold itself to form the parts. I never tried to do this with an oven, so I don't know if it works without the mini torch.
If you don't have a torch, a little gas lighter can do it, but with less control. The secret is to move the flame all the time, and never to stop the movement. If the flame is directed to the same place for about two seconds, the plastic first turns milky, and then starts to melt, so constant movement is the key.
You can find those torches at places were they sell cigars.

Here is the picture tutorial:



















The windshield in place:

[Hoosierfarmboy]

What type of clay did you have under the bad winshield ? Also did you remove the broken piece b4 you applied heat? I have wondered if something like this was possible

[sports850]

That is cool , opens up potential for a lot of small shaped panels actually (like a clear mini bonnet perhaps)

[Lovefordgalaxie]

What type of clay did you have under the bad winshield ? Also did you remove the broken piece b4 you applied heat? I have wondered if something like this was possible

That's not clay, its epoxi putty, and believe me, it has to be a strong stuff, when the plastic starts to shrink it gets really tight.
I don't remove the bad windshield, as it is the template for the new, it only has to be smooth (you have to sand the glued part smooth) before being used, because every imperfection will show on the "new" windshield.

[bill_rules]

WOW ! Even better than the original, it's more to scale in thickness. Thanks!!

[kobuzz]

Is that just a regular 2 liter bottle like Coke, Dr Pepper, ect? Very cool trick.

[Lovefordgalaxie]

That is cool , opens up potential for a lot of small shaped panels actually (like a clear mini bonnet perhaps)

Oh yes, the oly limitation is the size of the plastic bottle. A clear bonnet is easy, you just have to reinforce the template with some epoxi putty to avoid any distortion, and you are done, not to mention you can build as many as you want.

[Lovefordgalaxie]

Is that just a regular 2 liter bottle like Coke, Dr Pepper, ect? Very cool trick.

This one in the pictures is a section of a 2 liter Pepsi bottle. Can be any PET bottle that's clear, and smooth. In fact, you can actually build colored glass if you want, like green, blue or red, just use a colored bottle!!

[rustymodeler]

Hey man, I have tried this in the past and got frusterated, because the new windshield part ends up bigger than the whole its supposed to go in. I will try it your way and see if that makes a difference. Thanks for the tip.

[peekay]

Great tip, thanks for sharing. And as bill_rules says, the result looks better than the kit piece, which is kind of thick and distorted.

[Steve Milberry]

What a great tip !!

I've heard of the vaccuform method and the "heat and mash" method [which I've used a couple times] but this seems to beat tham all.

Thank you so much for shareing this with us.

[sjordan2]

Tulio's tutorial is quite good. Once upon a time, Squadron sold a Thermaform process that worked like that, used mainly by aircraft modelers to duplicate canopies. I believe they have discontinued that product (supposedly using a "proprietary" material - I have several sheets left). Their instruction sheet is below: I used a heat gun - a hair dryer on steroids, which was intended for shrinkwrapping. I tried this on a dime and I could read the mint mark.

http://www.squadron....view-sq9003.htm

Someone may have more experience than I do on the variety of materials that can be used, but wouldn't vacuum forming sheets work, such as those below? They offer clear PETG and ABS for this application.

This is also a good technique for creating glass T-tops (though you'll need to use your ingenuity for making the frames - maybe using the edges of the original T-tops or roof - and tinting the glass).

http://www.widgetwor...&show=50&page=2

I also tried this technique on an experimental basis using thin, clear plastic covers for report binders. It worked - except those covers turn yellow over time.

Edited by sjordan2, 21 May 2012 - 09:56 AM.

[wraith]

Very cool tip!
I have a diecast that I an redoing and all the glass in it is tinted red. ugh! So I might have to give this a try and that way I can get the clear glass i wished it had!

[Lownslow]

nice tip does it have to be a torch will a heatgun work?

[Lovefordgalaxie]

I think a heat gun will work just fine. It will be slower, but will work, yes.
Skip, I can't garentee it will always work wit plastic that is not PET.
The vac forming plastic is quite different.

[george 53]

WAY TO GO, Tulio!!!!! THAT'S a GREAT idea, THANK YOU!!!!

[Jdurg]

I think a heat gun will work just fine. It will be slower, but will work, yes.
Skip, I can't garentee it will always work wit plastic that is not PET.
The vac forming plastic is quite different.

Yeah, I think a heat gun would actually be a better instrument to use since the heat gun disperses its heat over a much wider area, thus preventing too much of a hot spot in one area with cool spots in another. With a torch, you have to be careful as the nose of the torch flame is super hot, and the temperature quickly lowers as you move further away from the tip of the nose cone.

I'm not sure if this would work, but to make the cutting away of the finished piece easier, you could take some really thin metal sheet and perhaps sharpen up an edge and place that where the edges of the finished glass would be. This way, when it droops and sags over your mold you'll have the sharp edge forming a thinner area in the glass. This would be easy to trim away.

Great tutorial though. I may make use of this when creating headlight lenses, or other lenses where the kit parts don't look right.

[Ace-Garageguy]

That is an absolutely OUTSTANDING trick. Thabks for posting it.

[sak]

Last time I tried this the original part melted and warped along with the new plastic. That I suppose it the purpose of the putty..to keep it from warping ?

[MrObsessive]

This is a great tip! Especially for those who aren't adept to bending clear stencil sheet for wraparound windshields or backlites like your '58 Edsel.

One of my MAJOR pet peeves in a lot of American kits is the way too thick clear "glass" that they include. There are certain kits I won't build for that very reason-----(AMT '57 Chrysler comes to mind). I'm certainly saving this whole thread for future reference. It will come in very handy down the road! I personally think a heat gun (or hair dryer) might be a better idea for most.

Sure it's slower, but it's also safer especially for novices who aren't familiar with using a mini torch properly.