UHMW misery

[Owen]

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


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"Enjoy Life, Race a Yamaha."

[Chris Fazio]

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

[Owen]

Thanks Chris. I'll be sure to give that a try when I get home from work.
Owen

[jero100]

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.

[Spin Doctor]

You could do the same thing with a back side tool post if your set up for one

[Rotate]

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

[Owen]

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

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"Enjoy Life, Race a Yamaha."

[wierdscience]

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.

[Thrud]

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.

[jero100]

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