RE: CRT tint masks

> http://marvin3m.com/vacuum/index.htm
>
> Basically they heat up a piece of PETG in the oven then drape
> it over the desired surface. Now I'd just need to find a
> source of tinted PETG at a reasonable price (found 24" x 24"
> for $25...seemed a little pricey...must keep looking).

Yeah, it's actually even a little easier if you use thicker plastics since
they retain heat better and stay flexible longer. I used to work with a guy
that built a (pretty fancy, actually) vacuum forming rig to reproduce Storm
Trooper armor from molds taken original from the movie props. The amount of
vacuum you can produce along with the temp of the plastic plus the mold
design dictates how deep of a draw you can get and how defined your corners
and details are.

Mold making is a bit of an art-- it's not necessarily just a negative of the
shape you want because you need runners for the air to escape and different
drafts to get the desired wall angles, etc... My friend actually evacuated
a pressure tank (used the $40 Harbor Freight one in 'reverse', IIRC) with a
vacuum pump and had a ball-valve on it to the table so he could more or less
instantly pull all the air in one 'bang' rather than a slower 'whoosh'. He
made some really impressive parts with it. He took a mold of my I,Robot
control panel but I don't think he ever reproduced it. I've thought about
trying it myself to do an Outrun control panel. (I have one NOS and like
three broken ones-- I know the NOS will get broken at Ground Kontrol, so
it's either reproduce it or maybe just repair the old ones with some
fiberglass or carbon fiber and epoxy and repaint 'em. ;-) Maybe when I
retire... ;-)

I suspect that if you got those theater gels (maybe the polyester/PETG ones
would be easier to work than the polycarb) you could probably just put the
front glass from a scrap tube in the over and set the plastic on top of it.
Heat it up gradually and I suspect that gravity would do the rest...
 
> Yeah, I tried that route but wasn't pleased as it didn't stay
> well and bubbles were an issue.

True... Bubbles do form over time in that stuff and require a re-do.

-Clay

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Received on Thu Feb 5 01:23:55 2009