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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
    2,482

    Post

    You could do the same thing with a back side tool post if your set up for one
    Amatuers cut gear teeth one at a time. Professionals generate them via gear hobbers and shapers

  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
    17,036

    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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