"John R. Carroll" wrote in message
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"Ed Huntress" wrote in message
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"John R. Carroll" wrote in message
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"Ed Huntress" wrote in message
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"Ignoramus20251" wrote in message
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I personally disagree with bashing of flood coolant as used on
lathes. (and, granted, I do not have much experience).

First, with reasonable speeds, flood coolant is not being sprayed
around by rotating parts that are being turned. Not enough centripetal
force, at speeds that seem reasonable to me. The only way it would get
sprayed around, for me, is if it would find its way on the chuck
itself, as in turning near the chuck.

Iggy, if you're not turning fast enough for that coolant to fling half
way across the shop floor, you aren't turning fast enough to justify
water-miscable coolant.

Sorry Ed, that just isn't true.

JC

Oh, boy, shades of cool-grinding HSS. g

OK, John, please tell me why it's not true.

Well drilling and tapping for two but believe me Ed your tools and
finishes will defenitely benefit from a steady stream of coolant.

OK, let's explore this, because this is the heart of what I'm talking about.
This is where carrying over production practice to hobby practice can result
in misconceptions.

Yes, a stream of fluid will flush chips and greatly improve drilling and
tapping. Through-hole flushing is best, but a well-directed stream helps a
lot if the holes aren't too deep, even without through-hole flushing.

But that's NOT because it's coolant. It's because it's fluid. As you know,
gun drilling in difficult material was (maybe still is) done with
through-hole flushing of oil, not coolant. Oil is a much better lubricant
and it will give better performance in most cases.

However, it's expensive; modern cutting tools often don't need it (as many
don't need, or benefit from, cooling); and it's a mess when applied as a
flood in production. Anyone who has been around a gear-hobbing production
operation that uses a flood of oil lubricant knows all about it. I used to
go through a pair of leather-soled shoes every few months when I was
covering gearmaking. g

In a hobby operation, most people don't have a sump, a pressure coolant
system, and flex nozzles. They don't have through-hole tools with glands and
pressure fittings. But some get the idea that it's the coolant that's the
issue here, when the fact is that coolant is just a lot cheaper and leaves
somewhat less slime on the floor. And it creates some problems that you
don't have with oil, which matter in production but not in a hobby shop.

A travelling shield ( on the cross slide) and a coolant stream are worth
the trouble.

As for tools benefitting from it, what kinds of tools, run at what surface
speeds? Again, let's separate the layer-cake exotic coated carbides, CBN,
ceramics, coated diamond and so on that you may be using in your commercial
operation, often with radiused edges that we could barely get to cut in our
old (or Chinese) machines, from the HSS and plain grades of carbide used in
the typical hobby shop. This is, after all, RCM, and this kind of basic info
is of greatest interest and use to hobbyists.

In general, in commercial machining, tool life is a minor factor in the
production cost equation, as you know. In a home shop, it's a very big deal.
Oil will, in most cases, give longer tool life under hobby-shop conditions
than will water-miscible oil. We don't need cooling unless we're pushing the
envelope for maximum production rates. We need lubrication to protect tool
edges and to reduce cutting forces, partly to get the most out of the feeble
horsepower our old machines have and partly to minimize the spring of those
old machines, like my South Bend 10L.

You mention improved surface finish with flood coolant. Again, compared to
what? At what speeds, and with what kind of machines? Most hobby machinists
use a brush or drip lubrication. If we have the luxury of pressure
lubrication, we may get better finishes with flood *coolant* (although I
doubt it -- try using some modern mineral-based oil on the same job some
time), but it's NOT because we're using coolant. It's because we're using
pressure to get fluid into the cut interface a little better than you can
with drip or by brushing ahead of the cut.

One place where the different effects of lubrication really show up is in
cutting a deep, long thread, or an Acme thread. Try it with sulfated oil, or
even a plain mineral-based cutting oil, and then with a typical coolant, on
a long screw on a 50-year-old lathe. That's a real test, and the oil, in my
experience, beats the coolant hands-down. There's just a lot less drag on
the tool, which pays off in several ways.


I had a guy instruct me on the fine art of facing, drilling and then
tapping pillar supports once. I'd finished fifty of the things without a
hitch by the time he'd realized the joke was on him.
Shall I tell a story or sing a song?
LOL

I'm not sure I'm following you, but it sounds like a production story. I
don't think I've ever made 50 of anything in my home shop.

--
Ed Huntress