www.TK560.com

[SPACEMAN]

well im gunna start off a little poverty stucken and use my vaccume and oven to try my hand at vaccum forming , IM GUNNA TRY TO MAKE A HEADLIGHT LENS FOR MY CAR . MY ? IS WHAT THICKNESS DO YOU THINK I SHOULD TRY .I WAS FIGURING ON 1/4 OR SO ? unless i can go thicker .HAS ANY ONE TRYIED IT THIS WAY AND CAN HELP ME OUT .pics would be great . IT MIGHT SPARK ME TO BUILD A DECIENT MACHINE ONCE I SEE THAT I CAN DO IT ,I SEE MOST OF YOU HAVE VERY NICE MACHINES AND PROBLY COST A NICE PENNY . PLEASE HELP

[jegner]

Well, I would consider .125 PETG as it is less shatter prone than Acrylic, and is about as easy to pull as ABS. I would test your machine with HIPS first, to learn how the process works.

[spektr]

You can choose to believe me or not, but I make an array of replacement plastic lenses for Porsches, have been doing it for years and still bet kicked in the teeth every so often..............

Heres the deal.... PETG will work IF (big if) the part can be cooled in use because it's Tg temp is quite low. Acrylic can be used if you can tolerate the fracture sensitivity, which on headlights is an issue do to the impact potential of the lenses. I find decent results can happen with .118, .125 and some .187 PETG, .120 and .187 Acrylic. Lexan works but you need to look at it so hard that a generalization on thickness isnt going to help you.

OPTICS..... None of the plastics have the same refractive index as glass, so gtting a plastic lens to focus like glass is very difficult. If you are attempting to replicate a newer bonded headlight housing with a coated polycarbonate lens, you should be able to make the skin for it without too much problem. The shape is easy to replicate, BUT injected molded polycarbonate will have a different refractive index than sheet molded parts. This is due to the IM parts varying thicknesses and sheet parts being unable to match the thickness profiles of the IM part. Consequently, they will look acceptable but fail to focus.

Our plastic lenses will not focus like glass, we are replaceing glass for cosmetic purposes in daylight conditions. I hope Im painting the picture in a way that you find helpful.

Tooling.

Optic parts require squeeky smooth epoxy or polished cast aluminum tooling to make parts without markoff. Tools are usually heated to keep the plastic from developing "chill marks", areas of local shrinkage that make things yucky. Lots of work for you if you arent hip to whats going on. I've been doing this a while, and tooling for optic parts still have a bit of voo-doo in their design.

More later when you can tell me just what lens you want to remake.....

Scott.

[SPACEMAN]

well i was not planning on having the lens purpose on focusing the beam ,i was planning on making a set of color matched (blackout) for car show purpses mainly .i also considered making a a lens that would be clear so when i customed a projector in there it would work as an outside lens thats just there to cover from the weather rather than to focus the beam.
am i making it clearer to what i want to do or am i missing your point .let me know ,im all ears for advice on a subject i dont have any experiance in

also how do i post pics ,i have a question about something i want to make out of abs or plexi if i have to andi feel that if you saw it ,it would be better.i just cant figure how to do it