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How to make plastic disks

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  • How to make plastic disks

    Hey guys,

    I need to cut a bunch of 1" diameter circles from 1/16" polycarbonate. They need to be pretty accurate within a few thou, without damaging the clarity of the plastic.

    I have a mill, lathe, and some basic tools. I thought about taping down the plastic sheet, but cleanup can be really difficult and getting them off the tape without damaging them is hard. I would need to make about 50 of them.

  • #2
    1. Turn a .75" diameter cylinder about an inch long.
    2. Put a 60 degree cone in one end.
    3. Put this on the tailstock.
    4. Use a faceplate or a wasteblock in a chuck on the lathe.
    5. Rough cut a circle with a bandsaw.
    6. Place the rough cut circle on the faceplate.
    7. Bring the tailstock up to the workpiece.
    8. Turn the 1" circle.
    9. Repeat 50 times.

    Comment


    • #3
      Originally posted by elf View Post
      1. Turn a .75" diameter cylinder about an inch long.
      2. Put a 60 degree cone in one end.
      3. Put this on the tailstock.
      4. Use a faceplate or a wasteblock in a chuck on the lathe.
      5. Rough cut a circle with a bandsaw.
      6. Place the rough cut circle on the faceplate.
      7. Bring the tailstock up to the workpiece.
      8. Turn the 1" circle.
      9. Repeat 50 times.
      I like this, but I would replace step 5 with rough cut with annular cutter

      Comment


      • #4
        I would find a sign shop that has a laser and have them cut.
        I did the very exact thing. Look at my steam punk thread and look at the lens I cut. It was .062 material.
        Would probably take all of 10 min to get them all. Each one would be perfect.

        Sid

        Comment


        • #5
          Make a 1/2" wooden disk ~0.9" in diameter. Center drill the disk.

          Mount another piece of wood (preferably a disk) that is ~ 4-5" in diameter in a 3 jaw chuck. Use real wood, not plywood here.

          Face the piece in the 3-jaw.

          Cut your pieces of PC larger than your ultimate goal.

          Place a piece of PC on the wood in the chuck, then place the small wooden disk over the PC, then move your tailstock (with a center in it) to insert into the center hole of the disk. Lock down your tailstock, then run the ram up until tight.

          Use a sharp HSS cutter to trim the disks. Use a high speed, but below the point where the PC starts to melt onto the cutter.

          Using this method, you should be able to mount two or three at a time (stacked) to accomplish the task at hand.

          Comment


          • #6
            I did thousands way back when I worked in an instrument shop. Generally 2 1/2" diameter and larger, but occasionally 1 1/2".
            All we did was compress an impressively long stack of blanks (paper still on) between flat 'centers', one in the 3 jaw and one in the tailstock.
            Surprisingly, I never once had the stack 'let go'.
            Location: North Central Texas

            Comment


            • #7
              Originally posted by Michael Edwards View Post

              I like this, but I would replace step 5 with rough cut with annular cutter
              This for cutting your blanks out. JR
              My old yahoo group. Bridgeport Mill Group

              https://groups.yahoo.com/neo/groups/...port_mill/info

              Comment


              • #8
                Originally posted by Joel View Post
                I did thousands way back when I worked in an instrument shop. Generally 2 1/2" diameter and larger, but occasionally 1 1/2".
                All we did was compress an impressively long stack of blanks (paper still on) between flat 'centers', one in the 3 jaw and one in the tailstock.
                Surprisingly, I never once had the stack 'let go'.
                Was about to suggest this.

                So how long stack is too much? I think it comes down to diameter/length ratio, 1:3 probably works and 1:20 for pretty sure doesn't work
                Location: Helsinki, Finland, Europe

                Comment


                • #9
                  I did something like 450 discs from uhmw at one point. Hole saw did a nice job. In this case I needed the central hole so I used it as a guide- plus to be able to cut the discs out from both sides for a cleaner end result.

                  Without the central hole you can still do it easily, but from one side only.

                  A trepanning cutter works nicely- set something up in a boring head.
                  I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                  Comment


                  • #10
                    Vacuum chuck would solve the holding question, would be pretty easy to make something up to the task of plastic cutting

                    For the cutting, question, is a hole in the center of the disk allowable or no? If a pilot is okay, id grab one of these: https://www.amazon.com/General-Tools.../dp/B00004T7P1
                    Lets you dial in the cut diameter, and get the cutter nice and sharp and youd get cleaner results than you would with a hole saw. If thats not an option, rig up a boring head with some form of trepanning cutter maybe?

                    Comment


                    • #11
                      Originally posted by kuksul08 View Post
                      ... I thought about taping down the plastic sheet, but cleanup can be really difficult and getting them off the tape without damaging them is hard. I would need to make about 50 of them.
                      This firm sells double-sided tape which they have specially made for the purpose. It makes a world of difference compared with the ordinary stuff. I don't know if they supply outside the UK. Usual disclaimers.

                      George B.

                      Comment


                      • #12
                        Originally posted by Georgineer View Post
                        This firm sells double-sided tape which they have specially made for the purpose. It makes a world of difference compared with the ordinary stuff. I don't know if they supply outside the UK. Usual disclaimers.

                        George B.
                        What Firm? Link?

                        Comment


                        • #13
                          Originally posted by Joel View Post
                          I did thousands way back when I worked in an instrument shop. Generally 2 1/2" diameter and larger, but occasionally 1 1/2".
                          All we did was compress an impressively long stack of blanks (paper still on) between flat 'centers', one in the 3 jaw and one in the tailstock.
                          Surprisingly, I never once had the stack 'let go'.
                          This works and I also have done it. A piece of tissue paper between each one and stack em up with something thick on both ends.. I did stacks about 3" long with good results starting from square cut material. It's so easy with a sharp hss bit you'll be amazed.

                          Comment


                          • #14
                            There's lots of ways. But the fast and easy one that doesn't require buying any new cutters or other tooling would be the pressure turning options mentioned a few times.

                            Live center in the tail stock and turn up a pusher with a deep drilled center hole and 60° bore on the one side so it gets support off the whole length of the point.

                            And provided the sheet stock still has the protective paper on it you can rough out a bunch of square or octagonal blanks and likely stack cut 10 to 15 at a time. And once you have the numbers for the proper diameter off the first batch each of the subsequent batches would go even faster.

                            No need to buy new cutters and no need for double sided tape... which for a few only would be the way I'd go. Where fussing with the tape uses less time than making up the pusher for the live center it would be the way to go.
                            Chilliwack BC, Canada

                            Comment


                            • #15
                              Originally posted by sid pileski View Post
                              I would find a sign shop that has a laser and have them cut.
                              I did the very exact thing. Look at my steam punk thread and look at the lens I cut. It was .062 material.
                              Would probably take all of 10 min to get them all. Each one would be perfect.

                              Sid
                              Sid is right on. I did this with a laser at the TechShop, and it is a good way to go. Unfortunately the TechShop closed.
                              Larry

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