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How to cut polycarbonate

Discussion in 'Scenery, Props, and Rigging' started by jwl868, Apr 2, 2009.

  1. jwl868

    jwl868 Active Member

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    What are the options for cutting clear polycarbonate (Lexan) sheet? The sheets are thin, the kind one can buy at Home Depot (I think it’s about 0.1 inch thick).

    I’m using the material as a window pane for a semi-circular opening, about 24.5” x 12.5”. The pane will be mounted behind the opening, so none of the edges of the polycarbonate can be seen. I don’t need to make a curved cut, but I have to cut down the rectangular piece that I’ll be starting with because of interferences behind the opening.

    My choice of implements of destruction are limited: hacksaw, saber saw, exacto knife.

    Thanks

    Joe
     
  2. soundman

    soundman Well-Known Member

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  3. Van

    Van CBMod CB Mods Premium Member

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    "You know what that smell is ? That's the smell of Poly-carb being cut in the morning. God I love the smell of Poly-carb in the morning, reminds me of Victory....."

    You will wear out your finger trying to score polycarb with an exacto, but it can be done. I've always found the big secret to cutting any-kid of plastic <acrylic, poly carb, abs, etc.> Is a slower moving, higher TPI blade. heat build up from a bandsaw or jig saw often results in a gummy mess. That being said, with the tools you have available try this: Un-do the blade in you skill saw, take it out and flip it backwards, so the teeth are pointing the wrong way. Re-tighten the blade. If at all possible set the entire piece of poly-carb on top of a sacrificial surface < top of a work table works fine if the TD isn't looking.> Now set the depth of the cut to the thickness of the sheet good if your poly-carb is.10" then set the blade to .12" or so, just enough to get through. Now put on safety glasses, ear plugs and if you are sensitive to icky smells, a respirator. Follow you line and slice right through.
    Important things to remember:
    Leave the plastic/paper sheeting on the Lexan until after it's cut.

    Put masking tape or board tape on the foot of your skillsaw to keep it from scratching the surface of the plastic, if you've already removed the sheeting, or if you need to re-cut it after the sheeting has been removed.

    Switch the blade back around before you let anybody else use the skillsaw.

    Wear long sleeves and a doo-rag if possible, plastic crumbs get everywhere and they're sharp!


    **** Goggles, safety glasses or a face shield are imperative when cutting any plastic sheet good. The little pieces of plastic that are thrown off tend to be Hot, sharp and tiny. They get everywhere, they can slice your arms up if you're not wearing long sleeves. I've cut plastic sheet goods on the tablesaw before and even with safety glasses on walked out of the shop with blood on my face 'cause I wasn't wearing a shield and little pieces of plastic had cut and embedded themselves into my face. < Yes Mark, That's why I look this way now...:rolleyes:>
     
    Last edited: Apr 2, 2009
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  4. cdub260

    cdub260 CBMod CB Mods

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    Just remember, a face shield is not a substitute for safety glasses, but a supplimental piece of safety equipment. You still need to wear your safety glasses under the face shield.
     
  5. jwl868

    jwl868 Active Member

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    Thanks for the input.


    But van, if by skillsaw you mean circular saw, it's probably not an option for me. The only circular saw blade that I have is standard wood-cutting blade that comes with the saw. On top of that, I'd probably mar the plastic in the process.

    How about the saber saw at low speed?

    Joe
     
  6. Van

    Van CBMod CB Mods Premium Member

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    Sorry, Miscommunication Yes I meant Circ-saw, and yes you can take any old wood working blade, cross or rip, and turn it backwards in the saw and use that for cutting plastic. I recommend doing that much more than using a Jigsaw / Saber saw. If you do use a saber saw make sure you use one that does not reciprocate. If you have a good Bosch you want to set the blade to up and down motion only.
     
  7. jwl868

    jwl868 Active Member

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    Although the thought of the experience of smoldering polycarbonate and flying plastic shrapnel was tempting, I used the box-cutter approach in soundman's reference. I only had to do 5 - 6 feet of cutting and the scoring-breaking method worked fine.

    Joe
     
  8. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    Table saw with a plywood blade is my favorite. If you are using a circular saw clamp some 1x4 on top of the plexi to work as both a cutting guide and to lift the blade up above the surface to prevent scratching.

    All the comments about safety gear are a must!
     
  9. David Ashton

    David Ashton Active Member

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    If using a jigsaw you need to frequently spray the blade with a release agent like silicon spray, this cuts down the heat so a cleaner cut and no re-melting.
     
  10. maccor

    maccor Member

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    Just finished helping a student make many cuts while she made a snake terrarium (sp?) for a prop. Started with the score and snap method...worked but is slow. She then took a metal straight edge, clamped it to a benchtop, with the cut line slightly hanging over, and used a jigsaw with a metal cutting blade in it on medium speed. The straight edge worked great to provide a guide, and keep the plastic from flexing. She didn't use any lubricant, and the blade didn't have a problem gumming up. I think the type of plastic may have something to do with that (she used the cheapest stuff you can get at Lowe's). She did almost make the mistake of removing the protective wrap before she made her cuts. Make sure that stays on to prevent any damage. Original post said something about window panes. Usually, when we use plexi for panes, we will "borrow" clear-ish trash bags from the janitor and staple behind the plexi to give the window more depth and reduce visibility.
     
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  11. pacman

    pacman Active Member

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    Nice tip, Van. I remember hearing years ago about flipping the blade over, but had forgotten it. I happen to have some acrylic with a crack that I need to cut down for re-use.

    Anyone have any tips for glueing & polishing to get that nice seamless look?
     
  12. MaddMaxx

    MaddMaxx Member

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    OK! Hear is the BIG SECRET! First when cutting ANY plastic sheeting use a table saw! There is a product that steel workers will know about called: Tap Magic. It will allow you to drill through even a 1/2" steel plate without creating any heat on your bit! It literally heat pumps the heat from friction away! I use it on blades for steel cutting also and can touch a blade right after cutting and it is cool! Extends the life of bits and blades. Since the problem with cutting plastics of any king is the melting and then immediate cooling and binding this product eliminates it! I have cut and drilled 1/8" cheap and brittle crap without any breakage or cracking. Get Tap Magic at your steel distributer.
     
    Last edited by a moderator: Aug 21, 2009
  13. headcrab

    headcrab Active Member

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    For short cuts tin snips work fairly well. They tend to leave a row of tiny notches on one side due to the serrations on one jaw, but the plastic doesn't crack and there are no flying bits. I've never had to cut any plastic thicker than 1/16" but I would assume this method wouldn't work on excessively thick polycarbonate.
     
  14. rcal

    rcal Member

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    I have to agree with all the comments about the PPE, I know a guy who scratched the surface of his eyeball and now can't see to well out of it, it was painful aswell apparently!
     
  15. kicknargel

    kicknargel Well-Known Member

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    We've had good success using a router (or laminate trimmer) with a small flute bit for cutting plastics. For straight lines, you'll need to clamp a fence down, but for organic shapes it works well. We discovered this making icicles out of prismatic poly-carb.

    Nick Kargel
    http://www.youwantwhatproductions.com
     
  16. ship

    ship Senior Team Emeritus Premium Member

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    type of plastic, its thickness as with length of cut or cutting fluid has a lot to do with melting thru.

    Too many teeth on the blade it melts, too few it breaks and cracks. Lots of play testing teeth per inch on the blade for length of cut so as to figure out whats best for your situation without good option for jigsaw.

    On the other hand scoring with matt knife on both sides sounds like a good idea for that thickness of plastic if not even following that up than with the jigsaw if not breaking cleanly.

    Reason even with jigsaw one cannot specify a tooth per inch specific blade is they vary by way of stroke length and one can vary the speed in use of them. I given say on average a 7/8" stroke length and hopefully not less than that, might attempt a 14tpi blade or 18tpi blade for that thickness dependant on the length of cut. This as not supplemented by above cooling solutions that are a good idea if not even luke warm water in this case perhaps.
    an
    Table saw or chop saw.... for that thickness I would go fine tooth and slow feed rate. For Jigsaw I might go 50% speed given a at start 14 TPI blade without orbit or even blade clamp that helps support but also helps heat it. If too rough for the cut assuming a short length I would go finer in blade, if too rough in cut for a longer length I would speed up my saw by 25%. If burning thru I would first speed down the saw some, than return to 50% and if still a problem go to about a 10 or 12 TPI bit. All about dialing into what you are cutting, it's length, the bit used, the saws stroke length (less stroke length the more hot the teeth engauged get) and speed of saw.
     
    Last edited: Aug 23, 2009
  17. BrianWolfe

    BrianWolfe Active Member

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    I have been working with polycarbonate for about 25 years. Given the choice of tools you gave I would use the jig saw with a fine metal cutting blade. Keep a piece of wood under the cut about 1/4" away from the cut to support the plastic. We put felt on the saw baseplate if the protective sheeting is removed A matte knife will work with very thin material but you should make many thin cuts with a very sharp knife. Using an angle iron as a guide can protect your fingers forma slip with the knife. Scoring and snapping with polycarb does not always work especially in thicker material.

    I would cut it with band saw if available or sheet metal shearer. It also cuts well with a router or as said before a cheap carbide blade turned backwards in a table or circular saw works well.

    Don't confuse polycarb with plexiglass. Plexiglass is an acrylic. Polycarbonate is much tougher stuff and is the plastic that bullet proof plastic is made from.
     

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