[Nastyzen]

Hi,I'm trying to get a nice finish turning some 2.625" dia grey pvc plastic Knobs out of round bar.What kind of rpm should I be at? I am now at 1200 rpm and .004 lead for finish pass.I also have inserts that are supposed to be for this purpose.
Anyone had experience with plastic?
Thank's

[PixMan]

Define exactly what the problem is with the surface finish. Is it looking like it's tearing up rather than cutting?

Which brand size, type, grade and tool nose radius insert are you using? For PVC, I should hope you're using an uncoated, dead-sharp one.

[Nastyzen]

Hi Pixman,
I think my problem was rpm and feed and feed direction with dull tooling.....
Should have better tooling on monday.Ill post the results when I have
something presentable.
Thank's

[Rustybolt]

As a rule of thumb on grey PVC. Run it at alum. speeds if not higher and use razer sharp tooling. Otherwise you just run the risk of melting it. If you have coolant all the better.

[Nastyzen]

Finally received the inserts on Tuesday.I was able to get something respectable as far as the facing tools go but not so much the parting.
I programed an M01 before every finishing pass to remove the swarff manually and it worked great other than opening and closing the door 400 times to get 100 parts made.The tooling for this was uncoated and ground finished ,very sharp.
The parting luckily is underneath any visually seen area of the part so I got away with it this time.I guess I"ll get plastic specific parting $$ tooling next time.
I tried using coolant on plastic and I was surprised to see that it improved the finish,but it is a little messy.Anyhow this part is for medical and can't have any liquids get in contact with it.
Tuesday also brought a thunderstorm which took out the shop pc network card and port com 1,16 of the 18 green led's in the lathe pat light?!And also took out the network card in the office pc.Thank god the cnc's were all off main n all.
But as my youngest son put it"Well Dad at least the lightning bolt didn't hit you!"
I feel better now.
Have a nice weekend all!