How would you bend polycarbinate (lexan)

I need to bend some 4 foot long (almost), 1/4" thick Lexan sheets. It does not have to be super pretty, just good enough. How can I do that?
i
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Ignoramus25935 wrote:

heat. ideally a strip heater. you can do this with a torch if you're careful. bend it over something.
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wrote:

that?
Perfect. Ideally, you want to mount it to something rigid with fiberglass mat insulation under it, and then rig up a couple of support strips on either side to hold the sheet just off the heater. Try a couple of test pieces first, but once you have the timing figured out, heat it up & it will bend in a nice straight line.
Doug White
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On Tue, 08 Mar 2011 19:16:21 -0600, Ignoramus25935

My strip heater is only about 42" long. It is a heater element out of a dishwasher straightened out and mounted in the channel from a single tube fluorescent fixture. These elements are 120V. When I have ice dams on the roof eve, I turn it upside down to melt channels for water drainage. Gerry :-)} London, Canada
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I love it when you talk dirty...
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That's why leftists breed like cockroaches!
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McMaster Carr used to sell, and probably still does, heat rods that you use to heat up plastic sheet for bending. This should work for polycarbonate, I have a vacuum former and it works with polycarbonate.
RogerN
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Sheet metal brake with radius nosing.
Lexan bends and holds its shape wonderfully.
(WARNING!!! A BAD THING just happened. I just discovered that blue Loctite destroys Lexan almost as quickly as chlorinated solvents do. It doesn't dissolve -- no. It sits for 15 minutes without visible changes, then collapses into tiny "kenerbles" about the size and shape of tempered glass fragments.)
LLoyd
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message

Now I wanna try that. I need to get me a couple beers and a bottle of blue loctite.
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Later, I put some on the surface of a piece, and it did not damage it.
However, when some was trapped between a nut and the surface of a sheet (torqued lightly, and I'm certain there were no defects in the piece) and allowed to cure, just about the time it hardened, the piece fell apart.
It might be mechanical -- the compound searching out microscopic defects, then (perhaps) expanding to break it apart. But I've seen this same kind of deterioration before, when I cleaned a lexan item with GC "Cloro- Cleen", and it disintegrated about five minutes later. Again, there was no solvent action, it just fell apart into granules.
LLoyd
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On 2011-03-09, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:

I am gonna try it too.
i

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"Lloyd E. Sponenburgh" wrote:

Which "Cloro-Cleen" The original was Carbon Tetrachloride.
--
You can't fix stupid. You can't even put a Band-Aid on it, because it's
Teflon coated.
  Click to see the full signature.
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Nah... this was mid-80s, so I presume it was perc, not CT.
LLoyd
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"Lloyd E. Sponenburgh" wrote:

You could have got old stock at that time. Some still had bottles on the back of the shelf that had been there 10 years or more. The only time they cleaned out old stock was when GC changed labels. I had several bottles that were Carbon Tetrachloride bought at the end of the '70s. The newer version would break down in the bottles and stink.
--
You can't fix stupid. You can't even put a Band-Aid on it, because it's
Teflon coated.
  Click to see the full signature.
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in

Doesn't have to be blue. The red stuff will destroy Lexan just fine. We had an overly concientious technician ruin a big job right before it was supposed to get shipped overseas. He decided adding Locktite would be a good thing. The machine shop had to work a lot of overtime to make a new assembly for us.
Doug White
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Glad to know I wasn't hallucinating! Thanks.
LLoyd
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I used to run a plastics forming company for Point Of Sales displays and bent all manner of plastics. For a bunch of bends then you will need two lengths of square aluminum tubing with water fittings to flow cooling water through. Space them about 1" apart. Then use a straight electric heating element in between them and about 3/4" down below the tube top surface.
Place the Lexan over the heating element and then gently lift an edge ever few seconds to feel when it is soft enough. You may have to flip it er to heat the other side, but do some test bends. Make the bend then shut off the power an hold the material until it sets. You can have a fan blowing on it after the heating element shuts off to speed up the setting.
For a one-off item you an do what I did to make a chip guard for my big mill. Run two strips of 2" masking tape about 3/4" apart either side of where you want to bend. Use four or five thicknesses of tape. Use a paint-stripping heat gun and move it up an down the bend area. The masking tape will absorb some of the heat either side of the bend. Again, you may want to flip it over to heat the other side. Don't get too close with the heat gun as it will blister. Take your time, maybe two three minutes to heat the Lexan through then make the bend. For my guard I just leaned the Lexan up vertically then heated both sides, made the bend then let it sit to cool down.
As another poster mentioned cyanoacrylate thread lockers will crystallize the Lexan (many other plastics too) and it will fall apart. Also do not try to bolt anything tightly through as that will cause stress cracks over a few weeks and it too will fall apart. If you have to bolt it, use thick soft rubber washers and minimal tightening torque.
Good luck.
Dave
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Ignoramus25935 wrote:

Do you have a heat gun? Make a fixture in the shape of your bend, and blow the heat gun at the lexan on the part that needs to do the bending, and let it droop as it softens, to conform to your mold/fixture.
A hair dryer isn't hot enough - you need one of those heat guns that says "CAUTION!!!!! DO NOT USE ON HAIR!!!!!" ;-)
Good Luck! Rich
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