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Mar 16, 2002, 12:39 PM
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DBlum's Avatar
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Stretch forming plastic parts


A few folks have asked me to detail how I make canopies and other plastic parts. It is quick,easy,cheap,and best of all produces nice results.
1. Start by carving a form for the part.I use soft balsa cause it's easy to work with. You dont have to go crazy filling the grain,because unlike vacuuforming,most of it won't show. I usually sand 80grit,220,and 400,and thats good enough.
2. Glue your form to a piece of wood tall enough to allow you to pull the plastic down over the sides.I have a small vise I clamp it in to hold it on the counter.Place this near the burner.
3.Thumbtack the plastic sheet(I use .010 to .015 thick) to a couple pieces of wood to use as handles.Don't use plastic coated thumbtacks cause the plastic melts and falls on to the burner.
4.turn the burner on high and hold the plastic 5-6in above it(I'm taking the picture.those are my stunt hands).Be sure to keep it moving to heat it evenly.Here comes the part that takes practice.
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Mar 16, 2002, 12:40 PM
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Mar 16, 2002, 12:41 PM
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Mar 16, 2002, 12:41 PM
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Mar 16, 2002, 12:51 PM
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5.The plastic will begin to sag,then it will tighten up just a little bit.Quickly pull the plastic down over the form,making sure it conforms to every part.The trick is to just pull far enough without stretching the plastic too thin.If you dont like the results,and the plastic isn't wrinkled too bad,you can reheat it and try again.Hold the plastic tight against the form until it cools completely.
6.Trim and paint.

It takes a little practice, but once you're able to do it there is no plane you can't build just because someone doesn't make a kit of it.
Mar 16, 2002, 12:52 PM
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Mar 16, 2002, 01:57 PM
Wow, great lesson in plastic forming. Thank you DBlum! I'm going to save the whole thing.

BC
Mar 16, 2002, 04:26 PM
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Good info, think we will leave it up top for awhile!
Mar 16, 2002, 05:07 PM
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The plastic drawing method looks like it works pretty good. For those interested in vacuum forming, which is very easy to do as well (trust me, IT'S EASY!), check out my website. I don't have an exact dollar amount for the cost of my setup, but I'm sure it was under $50. I purchased my plastic through SIG manufacturing (they are on the web). Anyway, for what its worth, just another method.

-Mike

my website
Mar 16, 2002, 08:16 PM
jah
jah
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jah's Avatar
Awesome, I want to do that when I grow up. Right now I can't play with sharp objects of hot things!

Seriously, thanks, yet another tid-bit from the Ezone!!!
Mar 16, 2002, 09:16 PM
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Carl Petersen's Avatar
Thanks Dave, gotta try that myself.

Jelly Beans in production,
Carl
Mar 17, 2002, 05:12 AM
Dave,

Thanks a million! I've saved it and will certainly make good use of the technique. No more paper mache for me.

RB
Mar 17, 2002, 05:40 AM
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Another method described sometime ago in open discussion from mumboender is folowing:

"For cowls and canopies, I carve a plug out of balsa wood. I insert them into a suitable bottle and hit it with a heat gun. The bottle will shrink around the plug and give you a perfect, lightweight part. "

the whole thread is:
https://www.rcgroups.com/forums/show...light=fuselage

appears to be a very simple and easy way of making plastic parts.
Does anyone have any experience?
Mar 17, 2002, 06:00 AM
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AussieParkflyer's Avatar
hey Dblum how did you tint that canopy?
Looks great.

I am very impressed to say the least with your workmanship and scale detail.

Any post by you is a "must read" for me :-)
keep up the good work and thanks.
Mar 17, 2002, 06:55 AM
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tinting


Aussie,

I don't know what DBlum uses, but I use clothing dye. I believe the brand name is Rit, it comes in a concentrated liquid or a powder, you have to mix both with water. All it takes is to pick out the color you want to tint your parts (black for the "smoked" look), and an old pan/pot that you don't care about...the pot will be dyed as well. Put the pot on the stove and heat it up to low---medium heat and put your plastic parts in. To adjust how "darkness" of the tint is directly proportional to how long you leave it in the dye.
Also, you don't have to throw the dye out when you're done, just put it in a container when its cool, and store it away until you want to dye some more parts...my tid bits. Hope it helps!


Good luck

-Mike


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