question for Perry Owens

[mescalero1]

Perry,
I see in your reply where you mill plastics on your mill attachment.
I would like to lathe bore some plastic.
Any tips on , feeds, speeds, tooling?

[perry owens]

I should point out that I am a scientist by profession, not an engineer, so my technique might make a real machinist cringe. My turning experience on plastics is limited to acrylics such as Lucite and Perspex. The main thing is to keep the work cool to avoid heat distortion - I use a cutting oil of unknown origin that you dilute with water and squirt it on the work in a continuous stream. Tools should be ground with zero top rake and about 20 degrees front rake. I was told that HSS tools give a better finish than carbide but I only have HSS tools anyway. Cutting speeds should be low, around 300-450ft/min, reducing to 50-100 ft/min for a good finish.
Hope this helps.
Perry Owens

[mescalero1]

Thank you sir, very helpful.

[Buffboy]

I have done quite a bit of machining of parts with a metal lathe and agree with Perry. Most of what I did was with hard nylons and similar plastics making bushings/bearings. Keep the speeds down or you will get melted shavings and those mess up your cutting tools. You generate a surprising amount of heat doing this and melted shavings really gum things up. I've used both HSS and carbide for plastics, either works as long as they are really sharp. HSS is better. Be sure to wear eye protection as the chips can have a lot of velocity off the work even at low speeds.

[mescalero1]

Having my surface grinder back is a comforting thing.