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  • Delrin question

    I need to buy a short length of 2" diameter Delrin. I've never machined or purchased Delrin before. I read there can be heat issues. I don't have coolant nor air on my EMCO Maximat V10. I just need to turn it down a hair so it fits inside a tube. Any advise on machining it would be appreciated. Is there any specific type of Delrin to be aware of or is Delrin, just Delrin?

    Thanks ...

  • #2
    Delrin is a brand of Acetal. It machines easily. I don't think you need to worry about heat when taking a small amount off. If it is a problem, use compressed air. Welding stores have compressed nitrogen.

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    • #3
      I made a bunch of Delrin parts many years ago. Medium speed and sharp HSS and it cuts like butter with no issues of overheating. It's actually better than UHMW PVC for this issue.

      The little amount it sounds like you'll be removing will be an easy job with no issues.
      Chilliwack BC, Canada

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      • #4
        Originally posted by BCRider View Post
        I made a bunch of Delrin parts many years ago. Medium speed and sharp HSS and it cuts like butter with no issues of overheating.....................
        +1
        Yes- Sharp HSS -No Carbide
        Rich
        Green Bay, WI

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        • #5
          Originally posted by Rich Carlstedt View Post
          Yes- Sharp HSS -No Carbide
          Ground carbide inserts cut it beautifully. I use the cheap generic ones intended for aluminium.
          Last edited by pinstripe; 06-19-2020, 01:57 PM.

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          • #6
            ... thanks, ordered some Delrin.

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            • #7
              You will not have any problems turning POM dry.
              This is a roller turned with a carbide full radius grooving insert, 1 of 280 parts. I only used coolant because it helps drive the chips into the pan.
              No coolant for the video, I do not desire a coolant shower (-:

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              • #8
                Delrin cuts like butter using HSS or carbide.

                12" x 35" Logan 2557V lathe
                Index "Super 55" mill
                18" Vectrax vertical bandsaw
                7" x 10" Vectrax mitering bandsaw
                24" State disc sander

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                • #9
                  There is one gotcha. If you are aiming for close fits, the coefficient of thermal expansion is about 7 thou/inch/100°F.

                  This can, actually, be a lifesaver if you're trying to fix two delrin parts together (say a delrin endcap in the spindle end of a delrin machine handle). Turn/machine them with a 'dovetail' interference fit, then use the large thermal expansion to 'heat shrink' the two parts together.
                  Location- Rugby, Warwickshire. UK

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                  • #10
                    the only heat issues I've had with delrin are when drilling it. Get too greedy with the feed or forget to clear chips and you can get a melted mess inside the hole that wants to become part of the original piece again. Also it can grab and self feed drills. Turning it is lovely though.

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                    • #11
                      I've had good results treating delrin like aluminum as far as speeds and feeds go, but it can be tweeked faster for production runs if needed. Sharp HSS with a tool radius greater than the feed rate and the finish is great. As for heat, if your pushing it then use water soluble oil. The water for the heat, and the oil to prevent rust on your machine. There isn't any special lube qualities needed. Thin wall bushings can be a challenge as the material is easy to flex when thin

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                      • #12
                        You might want to stop cutting every once and a while to break the swarf from becoming a rats nest. It can happen very easily. And I totally agree with the 'sharp' cutting tool comments.

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                        • #13
                          Delrin is one of the easiest plastics or any material to machine. You can push stupid high feedrates and speeds as long your workholding is enough secure. Drilling with large feed looks more like extrusion process (you can even feed normal twist drills so fast that they run out of relief angle and start rubbing)
                          Location: Helsinki, Finland, Europe

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                          • #14
                            If only everything machined and parted off like Delrin, forums would have a lot less How-To-Questions....

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                            • #15
                              Originally posted by mattthemuppet View Post
                              the only heat issues I've had with delrin are when drilling it. Get too greedy with the feed or forget to clear chips and you can get a melted mess inside the hole that wants to become part of the original piece again. Also it can grab and self feed drills. Turning it is lovely though.
                              Totally agree on all counts....

                              As with any plastic I strongly suggest the negative rake lip mod that also works well for brass. And again keep that negative rake scrapping edge nice and sharp and the drills will do a lovely and cooler cut.

                              I'm rapidly building up a "specials" drill index with brass and plastic negative rake drills. I do them as I need a new size and into the index it goes.

                              Good point on clearing the flutes though. Packed in chips will rapidly heat up and overheat both the work and the drill and then soften the body of the piece and then life seems a lot less happy.
                              Chilliwack BC, Canada

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