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Learning to Bend Lexan

  1. #1
    Mophead going grey dontpanic's Avatar
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    Learning to Bend Lexan

    I don't have any metalworking tools or skills, so I've started fooling around with bending some Lexan that I've had around the house. (I use it to close off the space above our air conditioners since our windows all slide horizontally, not vertically.) Lexan is GE's name for polycarbonate plastic sheeting, BTW.

    I got Brenda one of the closeout HP Touchpads, and was really annoyed at having to hold it the entire time I used it. Here's what I did with a scrap piece of Lexan (3/32 thick). I just heated the areas I wanted to bend with a propane torch and then bent them over the edge of the workbench:

    Learning to Bend Lexan-bending-lexan-1-jpg

    Next, I fooled around with an idea for mounting the Droid Razr in the car. You can see where too much heat from the torch caused the moisture in the plastic to cause bubbling when it got too hot.

    Learning to Bend Lexan-bending-lexan-2-jpg

    I wanted to do some brackets to adapt an SV1000S fairing to the upper fairing subframe of an EX500. The shapes were all compound curves, and I figured heating it in a stove would be better than using a torch. However, I couldn't find anything really helpful online. So, I've experimented on my own, and thought somebody might get something of value out of this.

    Here's what I've learned so far. Lexan will bend, barely, at 250°. It'll bend more easily at 275°. At 310°, it bends really easily. At 350°, it becomes like silly putty, but only for about thirty seconds.

    Learning to Bend Lexan-bending-lexan-4-jpg

    So far, I've made three brackets for the EX. They don't look terribly great, but they're strong as heck!

    I've discovered some useful things along the way.

    1.Use insulated gloves. Trust me on this one.
    2.It's helpful to have a pot of cold water nearby for when you forget rule #1.
    3.Going up on the temperature is best done s l o w l y. I spent 2 hours going up from 175° to 350° today to make the last bracket, going up in 25° steps. Even doing 15 minutes at 175° and then jumping right to ten minutes at 250° caused bubbling.
    4.If your wife agrees to let you use the stove, be nice and put down some tin foil on the baking sheet. Move the plastic piece around on the foil every half hour or so, so it won't stick to the foil when you're ready to work with it.
    5.Once you're ready to bend the plastic, you've got a minute or less. Be ready.
    6.Cut broad shapes before heating. This way, when a piece bubbles on you, you won't have wasted 45 minutes crafting that groovy shape you were hoping to have. Cut the finer aspects later. (A rotary tool works fine.)
    7.When you're cutting with a rotary tool, the plastic gets flung out at you, and it's hot. (See rule #2.)
    8.Drilling is best done with the finest bit you've got, and working up.

    Here's how I learned about rule #3.

    Learning to Bend Lexan-bending-lexan-3-jpg

    I'd be interested to hear what others' experiences are. Whatcha got?

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    Last edited by dontpanic; 09-22-12 at 04:41 PM.
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  2. #2
    Lifer
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    Re: Learning to Bend Lexan

    We work with polycarbonate sheeting fairly often, to make guards and machine parts. Rule #1 - bend it cold, if possible. Heat will make (the heated area) brittle.

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  3. #3
    Mophead going grey dontpanic's Avatar
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    Re: Learning to Bend Lexan

    How the devil do you bend it cold without snapping?

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  4. #4
    Lifer
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    Re: Learning to Bend Lexan

    Well, we have found that there are differences in the different manufacturers recipes. Are you using *real* Lexan, or generic polycarbonate sheeting? Lexan of 1/8"- 3/16", and sometimes even up to 1/4" should bend without snapping. I will have to ask my guys about any details, but we generally try to avoid heat.

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  5. #5
    Lifer
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    Re: Learning to Bend Lexan

    If you are using acrylic, PVC, or polyethylene, it will snap easily. Polycarbonate sheeting is the only one that bends without heat. We use the others as well, but for different purposes (window replacement, etc.). U.S. Plastics used to have a whole bunch of directions and lists of quality's and uses on their website.

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  6. #6
    Mophead going grey dontpanic's Avatar
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    Re: Learning to Bend Lexan

    Yeah, I'm using gen-u-wine Lexan. I'll be looking up U. S. Plastics asap.

    Edit: They pretty much confirmed what I learned on my own.

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    Last edited by dontpanic; 09-22-12 at 06:15 PM.
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  7. #7
    Lifer joeswamp's Avatar
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    Re: Learning to Bend Lexan

    Lexan is weird stuff for sure. It seems hard as glass but when you really stress it it bends like chewing gum.

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    Mophead going grey dontpanic's Avatar
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    Re: Learning to Bend Lexan

    I'm going to have to do some more experimenting!

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  9. #9
    Lifer Garandman's Avatar
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    Re: Learning to Bend Lexan

    If you sand the edges but want them smoother, you can wipe them with acetone. Unlike acrylic, if you scratch polycarbonate you can't buff out the scratches.

    We cheat. We have a Stratasys Fortus machine that can make any shape you can design in 3D CAD directly out of Polycarbonate. But's white only, not clear.

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  10. #10
    Old and Slow Sheppo's Avatar
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    Re: Learning to Bend Lexan

    I used to bend it in a sheet metal brake when I was making shit for my race car .

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  11. #11
    Lifer
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    Re: Learning to Bend Lexan

    Yup, that is what we use, Sheppo.

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  12. #12
    Lifer
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    Re: Learning to Bend Lexan

    If you can to sacrifice some strength at the bend, you can scribe it, or partially cut it using a tool that looks like a fish hook, and then bend it easily.

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  13. #13
    Senior Member smokinjoe's Avatar
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    Re: Learning to Bend Lexan

    I have used sheets of this to make fairing extensions for winter. You can get it soft in the oven and grab it with ovgloves and bend it to conour from the mirror to the fairing, blocking wind to your hands.

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  14. #14
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    Re: Learning to Bend Lexan

    now i want to make a full set of bodywork for my race bike out of lexan

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    Re: Learning to Bend Lexan

    I'm now curious as I would really like to make a pair of these:

    http://mts1200.info/mts12_faq/multis...1200_wings.htm

    http://mts1200.info/mts12_faq/multis...king_wings.htm

    This guy used something called Perspex but Lexan would be good too one would think.

    Dave

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  16. #16
    Newbie Slowride's Avatar
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    Re: Learning to Bend Lexan

    Quote Originally Posted by dontpanic View Post
    How the devil do you bend it cold without snapping?

    When I did commercial glass we would make lexan windscreens for bikes, we would basically use a round object at first to get the initial bend going (keep in mind slower is better). Then we would make a wooden frame jig for the shape we wanted and c-clamp it into place.

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  17. #17
    Lifer Garandman's Avatar
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    Re: Learning to Bend Lexan

    Quote Originally Posted by davemon View Post
    /This guy used something called Perspex but Lexan would be good too one would think.

    Dave
    Perspex is acrylic, AKA Plexiglass, Lucite etc. PC would be a better choice due to better impact resistance.

    Note that you can "line bend" PC with heat as is done with acrylic if you don't have a brake.

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    Last edited by Garandman; 09-24-12 at 10:18 AM.

  18. #18
    Wife calls me a member Svenny's Avatar
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    Re: Learning to Bend Lexan

    Perspex is the UK name for Plexiglass or Lucite, an acrylic material, and is not as impact resistant as Lexan, which is polycarbonate. Acrylic will snap if you try and bend it cold (like in a sheet metal brake). Polycarbonate can be cold formed in a brake, but will retain it's bend better if heat is used. Slow, even heat is important to avoid the bubbles. I may have some scrap pieces (12x12 and smaller) sitting around in my shop if someone needs some smaller pieces to mess around with...it'll either be 3mm or 6mm thick...I'll take a look for it later today.

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  19. #19
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    Re: Learning to Bend Lexan

    Quote Originally Posted by dontpanic View Post
    How the devil do you bend it cold without snapping?
    COLD FORMING

    A bend in Plaskolite acrylic sheet can be accomplished without applying heat. A minimum radius of 200 times the thickness of the acrylic is required to avoid stress cracking.

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  20. #20
    Lifer Stromper's Avatar
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    Re: Learning to Bend Lexan

    When I did thicker stuff I would run a saw a 1/4 to 1/3 through and then it would ben in a nice straight line.

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  21. #21
    Senior Member smokinjoe's Avatar
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    Re: Learning to Bend Lexan

    Dont know about you guys but here in the City I can get 1ft squares to practice with at plastic shops. You put it in the oven at like 190 & keep testing till its flexible/floppy. You hold it in shape while your girl sprays it with water to harden it.

    Fun for the whole family

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  22. #22
    Junior Member hdscarbro's Avatar
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    Re: Learning to Bend Lexan

    I made a windscreen for my SRX250 from Vivak. Here are some photos:
    https://picasaweb.google.com/hdscarb...eat=directlink

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  23. #23
    Mophead going grey dontpanic's Avatar
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    Re: Learning to Bend Lexan

    Now THAT is very cool....

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