I'm working on a project for a friend.   It's a display cabinet with a curved door where the glass has cracked.   No glass shops in town that I can find, including the wholesaler, do curved glass and one told me even when they order it, they've had problems.   Doing some research, it appears that my next option is polycarbonate (Lexan) in that it will take some bend and is UV resistant.  The piece sits in a sun room.

 

Before I plunk down a Benjamin for an 18"x48" sheet of it, I am wondering how it might bend in 1/8" thickness.   

• I've had variable results with some of the scraps I've experimented with.   The scrap I have is about 30" long and 12" wide.  It bends great on the 30" side, but not so much on the 12.  Unfortunately, the 48" that I need is the vertical and the 18" is the curve.  Does having more dimension in either dimension help or hurt the bending?
• Is there an orthotropic  property to polycarbonate (does it bend better along the length of the sheet vs. across the sheet)?
• Back when I was in Jr. High, we bent acrylic (Plexiglas) sheets into some tight shapes, but (a) I have no idea what the temperature was (b) this was acrylic, not polycarbonate, and (c) I don't have a 48" oven. 
• The guy at the glass shop said he'd tried to heat polycarbonate but just before it bent it blistered (he was using a propane torch, I'd use a hair dryer or heat gun).  In my limited heating, it did not seem to help much.  Would an afternoon in a hot car with some weight on top help the bending?
• If I managed to bend it into shape, does it have a memory to either stay in shape or want to return to flat?

Never tried bending it. 

Here's a website for a glass co. I've heard does good work on curved glass.

When I sold mechanic tools I called on a shop out at the airport that put the finishes touches to new turbo-prop aircraft and one of their jobs was to install the windshields... another was making all the upholstery products, and doing all the painting, inside and out...They started with clear flat plastic of some type,, heat it in small ovens then put it between lumber that had been formed the correct shape and let it sit till cool then wa-la, curved windshields for the large aircraft. So I say, if those dumb arse mechanics could do that maybe the average american like yourself could also do it...I never heard of any windshields falling out during their flights so, get yourself some lumber, build the forms and buy some plastic....sounds simple to me.....and the ovens were wide models built for home use....no biggie there .....

yes.. a lot...

polycarbonate isn't UV resistant...

it dries out and grazes...

 

corrugated_tech_manual.pdf

Cut, Drill, Finish, and Glue Acrylic.pdf

Lexan_940A_DataSheet_Polycarbonate.pdf

lexan_polycarbonate_sheet_processing_guide.pdf

ltc_technical_manual.pdf

LTCTechnicalManual.pdf

plexiglas-forming-manual.pdf

Thermoclear 2UV Manual Tecnico.pdf

Doing some research, I find:

- different than acrylic, you can cold bend

- no you need to heat it.

 

 

Another place says that do a curve the radius has to be more than 200 x the thickness.   My radius is 440mm, so ~2.2 mm thickness (or 0.0866") that is quite a bit thinner than the .118 mm (~1/8") that they told me would work.   (Lexan appears to be sold in metric, so don't yell at me)

7 minutes ago, Stick486 said:

yes.. a lot...

polycarbonate isn't UV resistant...

it dries out and grazes...

 

???

 

Description: This virtually unbreakable, transparent Lexan polycarbonate sheet comes with UV protection on one or both sides of the surface and provides remarkable clarity – even after many years of intense sunlight and weather extremes.

 

Polycarbonate sheet maintains glass-like clarity and is highly impact resistant and strong. LEXAN is approximately 250 times stronger than glass. ... Its protective UV coating and its insulating property also make it a reliable glass alternative.

warm it is more like it and vacuform it or hard mold it......

that radius is better done w/ a heat blanket/strips and not warming the full sheet

 

dumb design.

 

rebuild with normal, flat glass?

36 minutes ago, Stick486 said:

warm it is more like it and vacuform it or hard mold it......

that radius is better done w/ a heat blanket/strips and not warming the full sheet

 

Sign shops have ovens & do vacuforming, this might be the answer. Maybe you could make the curve with thin ply & they could heat and shape it for you.

I do know that some glass cleaners will fog Lexan.

windex will scratch lexan.

6 minutes ago, DuckSoup said:

I do know that some glass cleaners will fog Lexan.

 

dish soap solution is your best bet..

alcohol dries it out... as does vinegar..

 

why,,,,,, I was just bending the stuff with a  hear gun yesterday.

i love POLYCARB~!!!!!!!!   I mean the stuff is the best thing going, period,  the end,  absolutely.

With methylmerthaculate ( plexiglass)   all machining operations set up stresses that eventually cause the part to craze and break.  It's UV resistant  but  pretty much everything else  causes it to fail.  And it burns when drilled or machined.

 

With Poly Carb  these issues just  don't inhere~!!!!!

No need to put it in an annealing oven after machining. It doesn't burn easily, There is no stress build up. It bends with hear easily.  I love the stuff.

I replace windows with it I use it for ballistic  applications and It bends like buttah with heat.

 

15 minutes ago, DAB said:

windex will scratch lexan.

nope.  That's the cloth  used doing the scratching

 

45 minutes ago, Cliff said:

With Poly Carb  these issues just  don't inhere~!!!!!

 

it's still nick sensitive and will dry out if you don't seal you machining/cut/holes..