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How to make plastic disks

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  • #16
    My laser can't cut 1mm Polycarbonate cleanly. It chars the cut all black and takes about 5 or 6 passes at maximum power. On the other end it will cut 15mm Acrylic in 4 passes. It's a modified K40
    Helder Ferreira
    Setubal, Portugal

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    • #17
      Originally posted by KMoffett View Post

      What Firm? Link?
      Woops! Silly me.

      https://www.techsoft.co.uk/Products/...oubleSidedTape

      George B.

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      • #18
        Originally posted by Noitoen View Post
        My laser can't cut 1mm Polycarbonate cleanly. It chars the cut all black and takes about 5 or 6 passes at maximum power. On the other end it will cut 15mm Acrylic in 4 passes. It's a modified K40
        Leave the protective paper on when laser cutting, worked fine.
        Larry

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        • #19
          VERY INTERESTED!
          OOPS, I thought it said plastic dicks.

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          • #20
            Originally posted by challenger View Post
            VERY INTERESTED!
            OOPS, I thought it said plastic dicks.
            So, you got experience in cutting those things, do you?

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            • #21
              Thanks for all the great ideas!!! Wow!

              I think the stack of disks is an interesting idea. It would require cutting to rough size first and I feel like I would pucker pretty good hoping my tailstock didn't slip.

              One idea I had was to make a steel punch tool that I could simply hammer onto the sheet and it would instantly create the disks. But I'm not sure if it would just deform the edges and wreck them.

              Putting a hole in the middle is not an option. These would be used as lenses hence why it needs to be perfect in the middle.

              I asked a friend who has a laser and he said the reason the windows on laser cutters is made from polycarbonate is because it doesn't cut unless you have a very high power one. Acrylic is easier.

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              • #22
                I would try an arch punch to create a slightly oversize blank then finsh them in the lathe as others have suggested. When punching I prefer end-grain wood to punch into.

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                • #23
                  Originally posted by SLK001 View Post

                  So, you got experience in cutting those things, do you?
                  No! That's why I was so interested 😁

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                  • #24
                    Originally posted by kuksul08 View Post
                    Thanks for all the great ideas!!! Wow!

                    I think the stack of disks is an interesting idea. It would require cutting to rough size first and I feel like I would pucker pretty good hoping my tailstock didn't slip.

                    One idea I had was to make a steel punch tool that I could simply hammer onto the sheet and it would instantly create the disks. But I'm not sure if it would just deform the edges and wreck them.

                    Putting a hole in the middle is not an option. These would be used as lenses hence why it needs to be perfect in the middle.

                    I asked a friend who has a laser and he said the reason the windows on laser cutters is made from polycarbonate is because it doesn't cut unless you have a very high power one. Acrylic is easier.
                    Are the discs for a one-off project or a product that you how to market (even in limited #s)?
                    You might get a quote from a sign shop as suggested, you might be surprised at the price.
                    I think an arch punch will cause unpredictable cracking and crazing, even if oversize. Still leaves finishing to size and you won't know how many are defective until you remove the protective paper.

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                    • #25
                      Originally posted by reggie_obe View Post

                      Are the discs for a one-off project or a product that you how to market (even in limited #s)?
                      You might get a quote from a sign shop as suggested, you might be surprised at the price.
                      I think an arch punch will cause unpredictable cracking and crazing, even if oversize. Still leaves finishing to size and you won't know how many are defective until you remove the protective paper.
                      Good point.

                      I will contact a sign shop. This is for a low production run so I might mill them out manually even though it will take a while. Eventually I will outsource all parts and leave it up to the shop to figure out how to make them.

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                      • #26
                        I have also done perspex discs years ago for breast phantoms (don't ask).

                        Stuck a stack together with thin double sided tape leaving the film on the discs, turned with pressure from tailstock using a centre drilled blank.

                        Worked perfectly. Could not get the discs apart afterwards without damaging them.

                        2nd time no tape, there is so much friction from the protective film that it is like turning a solid block.

                        So as has already been suggested put up a stack, say 16, and turn your inch long cylinder. Worst case some little bits of plastic fly out.

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                        • #27
                          Earl,
                          How do you pre-cut the disks before you mount them?

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                          • #28
                            Originally posted by Earl Sigurd View Post
                            I have also done perspex discs years ago for breast phantoms (don't ask).
                            The things you can't unsee: https://www.peo-radiation-technology...hantom-gammex/
                            Last edited by reggie_obe; 12-21-2020, 12:03 PM.

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                            • #29
                              These were, shall we say breast sized, each slice was 10mm thick. Just chopped the corners off on a bandsaw and turned them using a razor sharp ccmt insert designed for aluminium.

                              Don't over think this. Put an inch thick stack of squares on the machine and do it. Takes less time than reading these posts.

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