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Thread: How to Drill Plastic Delrin Rod

  1. #1

    Question How to Drill Plastic Delrin Rod

    I am in the process of making bore guides for rifle cleaning .. I am using Delrin Rod.. but am having an aweful time drilling
    the hole thru the center .. I'm just using
    a regular drill bit , 12" long, with most of the shank turned down ..
    Is there a drill bit more better suited for the task and what should I use for a lube ??\
    Thanks in advance


  2. #2


    Never had much problem machining delrin. It machines very well, doesn't melt like nylon and needs no lubrication Make sure your drills are ground the same on each lip, use as short a drill as possible and use high lathe or drill speeds.

  3. #3


    135* split point should work. You may have to retract the drill often to clear chips or they will packup and cause you grief.

  4. #4
    Join Date
    Apr 2003


    It can vary but I find a slow speed similar to what you would use for stainless steel for drilling most acetron materials seems to work. Over heating the drill can be a problem so use air to cool your work and your cutter. This air cooling applies to most work in "plastic". There are drills specificly made for "plastic" but if you sharpen the bits you have to a very low angle you won't have a problem. In larger diameter holes the Fortsner style bits work well with air cooling.

  5. #5
    Join Date
    Oct 2002
    Cheyenne Wyo


    yes, what they said. I find if I let the drill flutes pack full, then there's problems. With frequent swarf clearing, it runs just fine.
    I'm here hoping to advancify my smartitude.

  6. #6
    Join Date
    Feb 2002


    I have made dozens of bore guides for Rem 700’s and Win 70’s from Delrin.
    I buy the ¾” Delrin and turn the outside first, drill the hole, and then cut the solvent slot.
    I make mine with a cut-off cartridge expoxied to the end of the bore guide this way it is a tight fit to the chamber and solvent usually doesn’t get into the chamber. Most of the bore guides I make have a 5/16” hole but I have made some with ¼” for guys that shoot .22 cal.
    Some of the Delrin will be bent when you buy it and will remain bent after turning the O.D. with follower rest and will create a problem when drilling the borehole. I have a piece of tubing with .700 I.D. and set screws on each end that I slide the bore guide in for drilling and this way I can drill from each end if the 12” x 5/16” drill bit will not reach the complete length.
    Oh, and as for drilling the hole, I let the tailstock slide on the ways, this way I can drill about ¼” and slide the drill out while turning about 500 rpm (Just don’t force the bit and cause a wreck). Like the guys said – don’t let the flutes pack up and use lubricant if you like. Actual time drilling the hole takes about one and a half minute.
    I will send you or anyone a picture of my bore guides if you like.
    Hope this helps you or someone since I have learned more from the guys on this board than I would have ever dreamed of.

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