Is it possible to heat & bend plexiglas, lexan, etc? - The Hull Truth

Semi · 01-19-2007, 04:47 PM

Anyone ever, or know if its possible, to heat a flat piece of plexiglass, lexan, or clear acrylic enough to bend it at a 90 degree angle?

Thanks

Ed Smith · 01-19-2007, 04:50 PM

Yes it is, but you had better know what your doing. To high a temp and it will melt and deform.

Semi · 01-19-2007, 04:53 PM

How? Heat gun?

mtcfish · 01-19-2007, 04:59 PM

You should use a router and cut a V groove on the inside of the bend. I've also used a 4" pipe and heated it over that but scrapped a few pieces using this method. If you heat it too much it will bubble...

2005FishermanWinner · 01-19-2007, 05:07 PM

i used a cutting torch ,heat gun was not enough. NEVER stop keep moving quickly side to side
how i did it was use a strip of angle iron as your bend point lexan laying over the angle iron so it dont absorb all the heat. clamp it to the angle iron. used 2 vice clamps close to each end to equalize the downward pressure with a strip of ferren across where you will attach clamps to the lexan and ferren

practice! you will need to practice to figure out how much you will lose due to the curvature of the bend when you bend you keep heating and test with pressure til it wants to bend then push the clamps down evenly also mark a point somewhere where bend will end , rebending will probably not be an option

davidridenour · 01-19-2007, 05:17 PM

I have a friend that makes displays and such for a museum. I was eyeballing a display and asked him how he bent the lexan. They go very early to a local pizza restaraunt and use the oven to gradually heat up large sheets. They take it out and bend it immediately. I'd say for a small bribe a similar arrangement could be made about anywhere.

moschoj · 01-19-2007, 05:32 PM

Yes. I straightened a piece of 1/2 inch thick plexy by placing it my oven. The trick was not to put the heat too high. I put the oven on 200 degrees and waited about a half hour before I touched it. The slow heat will ensure the plexi is evenly heated all the way thru. Torches and heat guns will deform it for sure.

Caution- Make sure there are no kids or women in the house and windows open. When heating up plexi it will release a toxic fume in the air.

SweetD · 01-19-2007, 05:46 PM

I also bent a piece of Lexan with my buddy in his garage - we measured and cut for the CC windshield, then he used a commercial heat gun on the top, and I used a smaller (like a "crafting") heat gun underneath, back and forth as evenly as possible where we wanted the bend. Bent it to 90 deg. over the edge of his large table saw. Worked pretty well, in hindsight we should have cut a groove at the bend area to make it bend more smoothly, but it came out pretty well for my needs - nothing too fancy but looks fine.

Dave

Shorty · 01-19-2007, 05:51 PM

Yes. I made a windshield for an old boat out of 3/16 lexan using heat. I did get some very small bubbles however. Now that being said, we use quite a bit of the stuff were I work and had to come up with a better way to shape it. We sent a piece to our metal fabricator and he is able to bend it 90 degrees in a heavy duty metal brake or bender. Not the ones for coil stock, but the ones for bending heavy metal. If you have a metal fab shop in your area, have them give it a try. Now as you probably already know, plexi will not bend, it is to brittle. Has to be Lexan or similar.

mymojo · 01-19-2007, 05:56 PM

Semi - I was pleasantly surprised to find out that my local auto glass shop fabricated a new windscreen for my boat. Its basically two pieces about 10" high curved along the top by 4 1/2' long each. They had a 60 degree bend as the screen wrapped around the dashboard. $250 total materials and fabrication so I thought it was worth it to have them do it and no worries for me.
You can make it out barely in my signature pic below up on the flybridge.

rwidman · 01-19-2007, 05:58 PM

I once made a project of 1/4" lexan and bent it with a sheet metal bending brake without heating it at all. It worked fine but it was a heavy duty brake. Actually, the guy who usually used the equipment made the bends, I just "supervised".

Eyeball · 01-19-2007, 06:23 PM

Semi, if you want to do it the right way (consistent results) you need to make/use an acrylic bender using nichrome wire. An electrical current is run thru the wire and it heats up and glows red like the zig-zagging wire in your toaster. The plexi is held over the red hot wire and it droops right over with a perfect bend, no flowing plastic to distort the plexi. In industrial applications they may run a tube of cold water on either side of the nichome wire to keep it cool on the sides, yielding a very narrow blade of heat for bending the acrylic.

The acrylic benders I have seen used were, ironically, homemade units at the boatyard. They are cheap and easy to make, also used by hobbyists that make model airplanes, cars, whatever. Google for where to buy the BARE nichrome (nickel chromium) wire. Also Google for the diy plans and formula for current to wire lengths, etc and what to use for the power supply.

If the length of plexi is short enough, and the little lady isn’t looking, just a couple of screws are holding the toaster together …

KeithS · 01-19-2007, 06:32 PM

As Shorty said we used to bend lexan with out heat in a press break in our sheetmetal shop. Be sure not to have to tight of a radii and you realy have to over bend your target angle because the stuff has a lot of spring back, a lot more than titanium.

1stGrady · 01-19-2007, 10:33 PM

Do you know anybody, (kids, teachers) at a high school that have Tech Ed, Industrial Arts, Technical school? We do acrylic bending and use a plastic strip heater to form the plastic. After one bend, any student can perform this operation. For a home-made strip heater I am thinking electric oven cal-rod unless the piece is too large. We made a windshield for a kids 16 foot bass boat out of 3/8 acrylic. Lexan, (polycarbonate) which will not break is a little more difficult to bend and is more suseptible to scratches. Over size the mounting holes so the screws do not chaffe the sorounding plastic which can cause cracks. File and sand the edges with some 150 paper then buff with an electric drill and buffer head with some acrylic buffing compound. It is also helpfull at the corners to make a small radius cut to relieve the pressure where the plastic tends to build up while bending. Wish you were closer, I could hook you up. Like previously stated, you could use an oven, but you will be very limmited as to the size. As an alternative, check out a local fabricator and get a price for bending. The other operations, drilling and buffing are pretty simple.

Jettywolf · 01-19-2007, 10:38 PM

SEE THIS GIGANTIC WINDSHIELD?

I HAD IT CUSTOM MADE.....I WON'T TRY IT. BUT I'D LET A PRO DO IT.

AND THAT WINDSHIELD COSTS $350.00 TOO!

and by the way.....I'll let ya have that whole boat with a brand new trailer for $18,500.00 FIRM.

Hookster · 01-19-2007, 10:38 PM

Quote:

mtcfish - 1/19/2007 3:59 PM

You should use a router and cut a V groove on the inside of the bend. I've also used a 4" pipe and heated it over that but scrapped a few pieces using this method. If you heat it too much it will bubble...

dpowell · 01-19-2007, 11:28 PM

I bent a piece to make a mount for a fish finder that didn't come with a bracket. I used a torch and kept a nice steady heat along the bend area with my son keeping pressure on the piece until it bent into the shape we needed. Pretty neat actually.

Semi · 01-20-2007, 12:27 AM

This is the website of the brand of lexan I got

http://plaskolite.com/fabguide/pg11.pdf

I have heated it in my oven at 320 degree's, and it bends, but I am trying to get two tight 90 degree right angles in it, and it just doesnt want to bend as tight as I want...

I have it fixed in place, and draped over a two inch piece of aluminum angle.
I dont think I can attach any kind of weight to pull it more sharply against the angle,
and its too difficult to pull it out hot and bend it againt a flat surface...

OK crud...just pulled it out from 350 dgrees and it got hot enough to bend closer....but now there are bubbles in it...

mtcfish · 01-20-2007, 06:58 AM

Use the V Groove router bit... tight as a ducks $^#

jerryk · 01-20-2007, 08:57 AM

Semi, I guess you were never my student. I teach Plastics at a high school in Miami. First, don't confuse acrylic plastic (Lucite, Plexiglas, Acrylic) with Polycarbonate (Lexan) They may appear similar but they are two completely different types of plastic. Acrylic heats at a fairly low temperature and if you put it in an oven (kitchen oven) the entire sheet will get soft and rubbery. If you need to bent it on a 90 deg. angle, you will need a strip heater. Most windshield we make in school are from 1/4 in smoked acrylic. You don't need any thing thicker. Forget about Lexan. It needs to be dried (pre-heated) in an oven before bending and even then, your bend temp "window" is very critical. If it gets too hot it will blister. Although Lexan is almost unbreakable. it is not as clear as acrylic which is optically perfect. A tip for all who have acrylic windshields,headlight covers on their car, never ever clean them with a glass cleaner (Windex). They will in time craze ( spider web designs) when the sun hits it. Use a kitchen wax, Jubilee or even a boat wax but never a glass cleaner.