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


OK, let's explore this,

Let's not and say we did Ed.
LOL
One thing your analysis omits is the lazy factor, if you want to call it
that, especially in a HSM environment.


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.

OK but I've seen a lot of guys ruin a drill when the squirt bottle runs ot
a half inch before the hole does.

Use bigger squirt bottles. g Better, use a fast drip, if all you're doing
is squirting it on. Drips are easy to rig up.



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.

I've never seen a lathe without a sump or a pan so you have me there.

Hey, my SB has a *pan*. You don't want to run flood coolant into that pan.
It's not made for it. It's about as deep as a saucer for a coffee cup.



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?

HSS or indexable uncoated carbide turning tools


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.

Exactly, and soluble oil (lard based) is probably what I'd be using.
Can you still get that sruff?

I don't know what soluble lard oil is. I use Buttercut, straight lard oil,
although I'll probably change to mineral-based when my current batch runs
out.

Did they ever make soluble lard oil?



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.

Consistency counts Ed. A coolant stream at low preassure that doesn't need
a third hand is going to give a better result overall because it's
consistent. Oil that isn't brushed on appropriately isn't much good.

Again, the issue there is consistency, not the use of coolant versus cutting
oil.


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.

Mold shops don't do production anything Ed, at least they didn't in those
days.

Well, 50 is at least a batch. g

John, we're getting two different subject mixed up here -- flooding the work
with cutting fluid versus the question of soluble oil versus straight oil.
Let me try to summarize my points:

Straight cutting oil is a good lubricant for cutting. Soluble oil is, at
best, mediocre. Coolant is good for cooling; straight oil is mediocre.
Coolant is cheaper, until you get into the real exotic synthetics, which
have little to offer the hobby machinist, anyway.

The lubricating qualities of your cutting fluid are very important when
you're machining in a non-commercial setting and your machine is low-powered
and/or flexible, and if you're using HSS or you're trying to extend the life
of your carbides. Lubricating the cut means much less when you're using
modern, powerful machines and advanced cutting tools with radiused edges. It
may even hinder your cutting if, for example, you're using a multi-coated
tool that contains a thick layer of aluminum oxide or a top coat of moly
disulfide. They both need a lot of friction to do their job.

Cooling is important if you're doing this for money and you want to optimize
your production rate versus costs. Cooling is all but irrelevant if you're
doing this for fun and you aren't punching a clock, as long as you're not
pushing your tools to the limit of surface speeds they can tolerate. Few of
us hobbyists are pushing our tools that hard, because we value tool life
more than flat-out production rates.

If you have the luxury of flood cooling, and you're willing to put up with
the mess on a machine that isn't fully enclosed, then flood cooling can help
some things. But it's because it's a flood, not because you're using
coolant. And some of the reasons flood systems are used commercially,
particularly in semi-tended or untended operation where you have to clear
all chips automatically and where you can't apply lubricant accurately,
don't apply in the hobby shop. Likewise, unless we're using CNC, we can't
fully enclose our machines to keep the crap inside. A spray shield is
half-assed at best. I've had to stand in the slop that gets around a shield
for hours and days on end. It sucks.

Unless you're a well-off hobbyist with modern machines and you like to push
the production envelope, flood coolant is problematic. And the key thing for
most of us is that we'll do better with straight oil for most cutting of
steel than we will with coolant applied from a bottle, a drip, or a brush.

I think the key misunderstanding many beginning hobbyists have is the
reasons *why* coolant is used in commercial machining. It isn't for reasons
that apply to most hobby machining. For most of us, oil is better. And there
is no reason, for most of us, to go to the trouble to apply flood coolant
just to cool the cutting tool. The simpler answer is to slow down a bit so
you don't need to cool.

There. g

--
Ed Huntress