On Fri, 29 Aug 2003 01:39:45 +0100, Andy Dingley
wrote:

Use lubricant. Something oily is good. Buy some RTD if you want (it's
gooey enough not to run away from a hole in a wall), but old engine
oil is a lot better than nothing.

Is it?

When I was out of cutting lube I trued using a squirt of Mobil 1 once.

It was really bad. The drill would not "bite", despite the
application of significant pressure -- and then when it did bite --
well fortunately the work was clamped really well (as it always is in
my shop ;-) so the drill-press stalled (only 3/4HP and a 12mm drill
bit).

It would appear that the film-strength of a good motor oil (a
synthetic anyway) is too high for it to function as a good cutting
oil. I would assume that cutting oil should be designed to have a
relatively low film strength so as to allow the cutting edge to reach
the work and actually do some cutting -- rather than skating around in
a thin film of oil.

But, given that I'm not an industrial chemist, I might be completely
wrong.

However, if you've got some synthetic motor oil in your shop, try
using some as cutting oil and see what happens.

--
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