...Only thing I can 100% guarantee they are not doing is working dry. In
stainless, that would result in an immediate loss of tooling.
Joe Agro, Jr.

I almost always cut dry or with a little brushed-on oil, at low speed
and manual feed. Do you have any handy rules of thumb on the limits of
dry machining?

We are talking stainless steel here I presume?

Brushed on oil is usually enough with stainless as long as you re-apply
somewhat often or the material is not really thick. If going dry, RPM rates
have to be super-low.

Rules of thumb for me are to never drill stainless dry. I use only HSS
tools so drilling SS dry results in immediate dull tooling. Stainless
simply does not carry heat away from the source very well and overheating is
virtually instant at normal speeds.

The chart on the following page presumes coolant for stainless and is a
conservative set of numbers in most cases:

http://tinyurl.com/ToolSpeeds

Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
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V8013-R