Tool sharpening and shaping for plastic

[Matt Ranum]

Curious if there is a shape to a tool that works better than others when turning plastics on a metal lathe?

[Bruce Boone]

I use carbide insert tooling on everything, and those certainly work fine. On normal tooling, sharper edges and good chip relief should be all you need.

[Chris Fournier]

As Bruce points out carbide works on plastics just fine but in my experience freshly sharpened HSS tools do the finest job and wear well too.

If you are using UHMW well nothing will cout it nicely! Acetal/Delrin turns very well.

[Johnny Kleso]

My experience is the oppsite..
On small lathes with less than 3 HP I find HSS works 10x better unless your cutting something extra hard

I worked at a place called ChemPlast now owned by Norton

You want a tool with a 1/16"+ raidus and very high top angle like 25º and side angles of about 15º
We ran the tools upside down to throw chips in to the pan..

On last passes you want to start cut very slow and stop cut to get a hold to the end of the chip and then start machine and pull the chip off the whole lenght as if chips wraps around work it may damage finish..

PS stone tool to a polish..

Let me use the correct terms open this pdf
http://www.metalartspress.com/PDFs/Sharpening_Steel_Lathe_Tools.pdf

Side and Back Rake 25º
Front Cutting Angle 25º
Side Clearance Angle 15º