Regarding "six sides instead of three":
If you are planning to use "negative" inserts, I'd think again. I have
an Altas 10 inch lathe and it is not rigid enough for negative inserts.
I use the "positive" inserts a lot, but they only have 5° or 7° of
relief (I don't remember which).
You really have to PUSH the "negative" tool into the work before it
can cut. That's where rigidity becomes a REAL issue.
Sometimes I switch to hss tools when even the front relief on positive
carbide inserts causes too much twist for the job at hand.

Pete Stanaitis
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