UHMW/UHMWPE Turning Pucks/Feet

A

aluminum

Registered
Registered
Joined
Nov 8, 2023
Messages
57
Hi folks,

I have tried several times to turn some UHMWPE (Ultra high molecular weight polyethylene) 2.5" round bar into these pucks. Trying to practice to make some pucks to use as feet/sliders. I get a decent finish by drilling, partially parting each puck, chamfering, then a finish pass, but after I part them off they look terrible. I am turning with support from a live center except for the final parting about 3/4" diameter). I am also having a hard time with chip breaking and stringing. Any advice for a better result?

I got this material for free so was hoping to be able to turn it. I also have some acetyl/delrin which I haven't tried for this application yet.

Thank you.
 

Attachments

  • PXL_20240212_160100738.jpg
    PXL_20240212_160100738.jpg
    457.1 KB · Views: 22
  • PXL_20240212_160114916.jpg
    PXL_20240212_160114916.jpg
    548.5 KB · Views: 21
first, it doesn't look like your tool is 90 degrees to the part. That is showing with the doming, and the tearing. The side of the parting tool is rubbing on the part tearing it apart.

But all is not lost, just face the part after ... for the future square the parting tool with the chuck.
 
UHMW is terrible to machine. It has great wear characteristics, but it is soft, dimensionally unstable and melts easily. Extremely sharp HSS tools are the ticket for turning this stuff, but you will never get the chip to break. It will form long ribbons that wrap around the part and chuck. The best you can hope for is to direct the ribbon into a garbage can. The difference between UHMW and acetal is night and day. Acetal is a joy to machine.
 
Everything MrWhoopee says plus I use every bit on rpm my lathe will muster. Just be prepared for a shower of stringing chip.
 
+1 on the stringy "chips" and the problem with them wrapping around the part. The strings tend to rub against the work and sort of re-weld to it, making for a very poor finish.

In addition to using a very sharp HSS cutter, I set up my shop vac to suck the string in as it's being peeled off the work.
 
homebrewed said:
+1 on the stringy "chips" and the problem with them wrapping around the part. The strings tend to rub against the work and sort of re-weld to it, making for a very poor finish.

In addition to using a very sharp HSS cutter, I set up my shop vac to suck the string in as it's being peeled off the work.
Click to expand...
Oh, and in addition to that I find it helpful to frequently stop advancing the cutter so the strings are short.
 
As Mr Whopee said; UHMW is a royal pain to work with; acetyl (Delrin) is a joy to machine, it was made with acetylene, which is distilled electricity, so it is a bit pricey.
 
If you don't grind your own HSS tools but use inserts, use a new CCGT or DCGT or TCGT insert. These G type inserts are ground and polished and have very sharp edges. I use them not only for plastics but also on aluminum and some times even on steel and stainless steel.
 
You must log in or register to reply here.
Back
Top