In article , Harold & Susan Vordos says...

Exactly as I do, too. I've found that the tops of parting tools respond
well to the radius of the wheel, so I grind what surely must be no more than
three degrees of positive rake on the tool as an almost last operation.
One has to start well back of the edge and extend the grind back to the
solid portion of the shank. Tools seem to have superior chip flow and
cutting ability with this minor variation. The only negative is as you
push the tool back from sharpening, the cutting edge drops slightly, so they
must be shimmed up. I keep a huge collection of shims on the headstock of
my lathe, so that's no problem at all. For those that use the insert type
tool holders (KDK, Aloris, etc.), it's a simple screw adjustment.

Interesting. I keep my home-grown grooving/cutoff tools with
purely zero top rake - I don't grind the top face at all. This
seems to work pretty well, given that these are most often
used as grooving or chamfering tools (with the indexable
toolpost kicked over a notch or two) and never get buried
more than about 1/4 inch deep in a part. Beyond that and I
reach for a real cutoff tool.

The Aloris holders do indeed put that three or so degrees of
back rake on their cutoff tools, but again I tend to run mine
at zero back rake, in a home-made holder. If they didn't
work tolerably well, I would consider making one with
rake (angled bottom to the holder) but so far it just hasn't
been needed.

Jim

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