About PVC: Yes, I used to make oodles of parts from it and it wore
tools worse than anything. Even to the point that when making a high
quantity of parts I could easily learn how much extra to turn the
handwheel with each part so I got the same finished size to make up
for the tool wear part to part. Of course, until the tool got so dull
it needed overall resharpening. This is also the time I became very
fond of using a diamond hone to touch up tool bits.
I also machined a lot of molybdenum-disulfide impregnated nylon.
(Sort of a plastic moral equivalent to "Leadloy".)
Chuck K.
Quoting John <John@...>:
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I doubt there is a "best" plastic for turning. Most of the less heat
sensitive plastics turn nicely if you use very sharp bits with low
rake and modest rpm -- plastic will self-feed like brass so zero or
negative rake helps if you take deep cuts. Regular bits work OK for
shallow cuts.
I've had good luck with: Delrin, nylon, HDPE, and polysulfone. These
are not too sensitive to heat but they do make long, stringy swarf.
Tufnol is less temperature sensitive and turns to dust rather than
strings - excellent for pulleys and gears.
Lucite is very temperature sensitive so it is much more difficult but
with care it can be used for lenses.
PVC turns OK, is a bit temperature sensitive and often has impurities
that produce surprising tool wear.
John
