To summarize what Lloyd sez:

Be sure the width of "finish" chips is less than the depth of chatter.

Bob Swinney

"Lloyd E. Sponenburgh" wrote in message
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"Proctologically Violated©®" wrote in
message ...
I have observed that it is possible to take too lite of a finish cut, in
both side milling and face milling, and in turning.
I've forgotten the exact scenario, but something like .002-005 was too
lite, and .015-.020 seemed to have been much better.
Whatever the exact differences in the numbers were, the appearance was
strikingly different, in manual lathe work as well.

That really depends upon the metal, your tool geometry, and the tool's
degree of polish.

I usually DO take less than half-a-thou on the last cut; normally, just for
cosmetics, but also for close fit-ups.

Really light passes, just pulling black swarf, require that everything be
very, very rigid. Take up all the lost motion everywhere, make sure your
spindle bearings are at the right preload, and snug up every gib. (and don't
forget all your feed screws' loading nuts, if you don't intend to lock a
particular axis.)

LLoyd