Here is a link to a 27 page PDF file that the Lexan Manufacturer publishes titled Lexan Sheet Processing Guide. P.8 has the procedure for Drape Forming Lexan. It seems to me to be geared to industry guide....but we are fabricators aren't we!! Knowing that they recommend around 150C is good gouge.
-
I like your idea of using an aluminium strip to spread the load - might try that.I did drill 3/8th holes for #6 screws and used a strip of aluminum over the stringers to help spread the stress of the screws and installed them fairly loosely. -
Sorry to hear that. Mine is 1/8th Lexan. I didn't try to heat form it. I did drill 3/8th holes for #6 screws and used a strip of aluminum over the stringers to help spread the stress of the screws and installed them fairly loosely. I would like to know what temperature is required to heat form the lexan. Would be beneficial for installing the lexan on my gullwing doors.
Leave a comment:
-
Polycarbonate (Lexan) Skylight
I installed my skylight yesterday and got small cracks around 3 of the holes. I see there are a number of threads discussing this already, but I’ve decided to put it here in case there’s some revolutionary advances that I’ve missed. Mine is a large skylight that I’ve modified to do in one piece. The result is that I am dealing with compound curves (I’m not as smart as I thought I was
)
I would have preferred to use Acrylic and heat formed it, and it’s something I’m still considering, the downside is that it’s quite a big task. Probably I’d make a mold and take it to a commercial shop and get them to do it.
The Polycarbonate on the other hand forms over the compound curves quite well. I suspect my problem occurred when I used Loctite on the machine screws, and it’s made the poly around those holes brittle. Unfortunately I only learned that after the fact.
I also had a tip to apply some heat to relax the lay of the poly where it bends, and I’ve tried this. It definitely looked like it was removing the stress from the sheet, however when I removed the skylight it still had its original flat shape. Probably it would help though, as I only need to reduce the stress where the holes are.
My main concern is what happens when I get fuel on it as inevitably it will. I’ve been trying to source a sheet that has Noxtat treatment for chemical resistance here in NZ but so far no luck.
Originally I had planned to use an adhesive to bond the Polycarbonate to the two center stringers. I still think it would be pretty strong, and even if it isn’t, the sheet is still captured on all four sides and almost impossible to remove without removing the side strips first. I even thought about not having anything retaining the center stringers. However it does “float†up at the aft end and would probably drum.
F5192880-6578-4B0D-857A-28A2925D30A6.jpeg
Leave a comment: