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Thread: UHMW misery

  1. #1

    Unhappy UHMW misery

    What's the secret to turning UHMW??? I was playing around with a 2 1/2" [6 inches long] solid rod. I wanted to turn it down to 2"
    Problem was, as I made each pass the material was staying wrapped around the rod. Almost like thread or string.
    Heavier cut? Was taking light passes of only .020" One buddy thought a larger radius on the nose of the cutter. Higher RPM? Currently working at 950rpm.
    Any and all suggestion gladly accepted.
    owen


    ------------------
    "Enjoy Life, Race a Yamaha."
    \"Enjoy Life, Race a Yamaha.\"

  2. #2

    Post

    Owen

    Had a similar problem with nylon. Ended up using a broad nose{big radius} hss tool with a good bit of positive rake. Would also try lowering that speed.

    Chris

  3. #3

    Thumbs up

    Thanks Chris. I'll be sure to give that a try when I get home from work.
    Owen
    \"Enjoy Life, Race a Yamaha.\"

  4. #4

    Post

    A larger radius helps with a heavier cut.
    I've found that a left hand turning tool, turned upside down, cuts better as it lets the chip ( or ribbon) drop straight into the chipbed.

  5. #5
    Join Date
    Nov 2002
    Location
    Kenosha, not the pass the other one
    Posts
    2,437

    Post

    You could do the same thing with a back side tool post if your set up for one
    The optimist says the glass is half full, the pessimist says it's half empty. The paranoid in me says somebody put a hole in it.

    Remember pessimists are at heart opptomists. They know things can and will get worse.

  6. #6
    Rotate Guest

    Post

    I had the same problem few months back.

    Stop the string from wrapping around by interrupting the cut, and also use a long tweezer to pull the string as it forms.

    Albert

  7. #7

    Post

    Jero100,
    I am safe in assuming the lathe is spinning backwards during your upside down technique? I am not set up for a back side tool post. Yet.......
    I haven't yet made it out to the shop. Was busy training all last night, home late.
    Thanks again to every one for the assistance with my UHMW misery.
    Owen

    ------------------
    "Enjoy Life, Race a Yamaha."
    \"Enjoy Life, Race a Yamaha.\"

  8. #8
    Join Date
    Jan 2003
    Location
    On the Oil Coast,USA
    Posts
    16,773

    Post

    Over the years I have machined tons of it my usual procedure is to use a slow speed and a fast feed something like 200rpm and .040"per rev. to rough out the part then high speed and about.005"per. rev.with a tool radius of about.032"for the finish cut.If that is not possible then what I do is start at the mill and cut a groove parallel the axis down just short of the finished od and turn as normal.
    I just need one more tool,just one!

  9. #9

    Post

    Owen:
    Ultra sharp tools. I have a HSS tool cut like an eagle talon - turn slow so the plastic does not melt. I cut off with a HSS blade with a viscious hook as well.

  10. #10

    Post

    Yes....sorry for leaving that out.
    once you get the chip going...gravity should pull the ribbon into the chipbed.

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