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  • Engraving Help Needed

    I am trying to engrave some plastic flashlights with rough results. I have started with a 1/16" 4 flute ball end mill and have varied my speed from 1200 to 3500 and my feed from 6IPM to 12. My depth of cut is .035". I keep getting rough edges with a lot of whisker hairs and my engraved areas are full of plastic swarf. It apprears that I am melting the plastic possibly. Any suggestions.

    P/R

  • #2
    It has been a long time since I did engraving, but I recall the specialized plastic cutters were single faced carbide, or rather one cutting edge. I think you need to try a different bit. Go for the least number of cutting edges you can get. Also, try a different bit geometry. I am confident the ball profile is a bad choice for plastics, and is causing too much friction at the center point, especially with such a small radius.
    Last edited by gmm22; 06-17-2008, 11:20 PM.

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    • #3
      Here is a link to the kind of bit used on sign plastic.

      http://cgi.ebay.com/2-New-Hermes-Eng...2em118Q2el1247

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      • #4
        Try using water flood coolant if possible. If not then use a direct and continuous blast of compressed air. Air works remarkably well as a coolant but must be kept on the point of contact at all times. I also agree that a 4 flute ball mill is not the right tool for plastic. You want as little edge contact as possible so either a two flute or a single edge cutter would be best.
        Free software for calculating bolt circles and similar: Click Here

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        • #5
          You are running that endmill way to slow and the feed is way to fast for a 1/16" end mill. Slow the feed down or kick the rpm up and it should clean up. 3500 rpm should be around 2.8 ipm. Ideally a 1/16 endmill should be ran somewhere upwards to 36000 rpm at 30 ipm.

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          • #6
            Ideally a 1/16 endmill should be ran somewhere upwards to 36000 rpm at 30 ipm.
            Not in a thermoplastic. You want the absolute maximum possible chip load and the lowest rpm that will do the job without breaking the tool to minimized friction and melting. The poster also said he is cutting at 6 to 12 IPM, not 30.
            Free software for calculating bolt circles and similar: Click Here

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            • #7
              you could try using a small center drill as your cutter

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              • #8
                plastic engraving

                I use 1/8" ball nose single edge engraving tools @ about 2,000rpm @ 10ipm on delrin & pvc sheet with vary good results

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