Cutting oil on lathe bits

The "Thatlazymachinist" on YouTube had a video that explained that the purpose of cutting oil was to enhance the flow of the chip on the face
of the cutting tool. I posted this comment question, but I'm getting impatient & I expect that someone here has the answer.
[quote] If cutting oil helps the chip flow along the face of the tool, it needs to be ON the face of the tool. But if it is applied to the stock ahead of the cut, how does it get from the surface of the stock to the face of the tool? This seems especially unlikely given that the chip is in constant contact with the face (how would oil get between them?)? [/quote]
Thanks, Bob
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I've wondered about that, and if the oil moves as hot vapor instead of liquid. There isn't all that much difference between low speed threading with and without oil. I think oil might improve the surface finish somewhat and reduce the torque when I pull the belt to run the bit up hard against a shoulder.
It could be informative to measure the torque to slowly hand crank the spindle on a roughing cut with the feed engaged, first without and then with oil. I don't know if a Kill-A-Watt would indicate power delivered to the spindle clearly enough to be useful. --jsw
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Whoever made that quite seems to think oil is like a thin layer of paint and can't flow at all or something like that. It's a pretty easy test to do too. Cut something that was oiled. Is the cutter oily? Ok, done.
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On 11/29/2016 3:11 PM, Cydrome Leader wrote:

Good point. I did that, being careful to not get oil on the tool before starting. And the tool stayed clean! Only makes me more confused.
Bob
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You could start a cut dry and then add oil to see how much difference it makes.
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typed in rec.crafts.metalworking the following:

    If memory serves from tech school, the cutting oil doesn't lubricate the chip, so much as cool the chip & tool. (After all, where the tool meets the metal,there isn't room for anything else. Cutting oil is last on the scene.)
    FWIW: I first read the subject line as meaning "how does one cut oil on a lathe?" -- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."
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wrote:

http://bbs.homeshopmachinist.net/archive/index.php/t-20828.html Sulfur isn't a coolant but it bonds to freshly exposed surfaces. -jsw
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On 12/3/2016 10:10 AM, Jim Wilkins wrote:

Thanks - the reply there explaining the 2 "regimes" of lubrication was especially interesting.
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On Saturday, December 3, 2016 at 11:48:55 PM UTC-5, Bob Engelhardt wrote:

That is a really good explanation. I might add one detail: it's not clear t o me which types of lubrication are involved, but some lubricants not formu lated for cutting (such as motor oil) can cause a cutting edge to skate ove r the work if the machine isn't sufficiently rigid or if the cut isn't suff iciently aggressive. This is why I cringe when people discuss cooking up th eir own brews of cutting oil, including the use of ATF. I have no idea how any individual concoctions perform, but the chance you'll get that combinat ion of normal lubrication and extreme-pressure lubrication right seems pret ty slim. Unless you use a lot of it and like to experiment, I'm strongly in favor of buying the stuff that's made and tested to do the job right.
--
Ed Huntress

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On Sunday, December 4, 2016 at 12:36:20 PM UTC-5, snipped-for-privacy@gmail.com wrote:

to me which types of lubrication are involved, but some lubricants not for mulated for cutting (such as motor oil) can cause a cutting edge to skate o ver the work if the machine isn't sufficiently rigid or if the cut isn't su fficiently aggressive. This is why I cringe when people discuss cooking up their own brews of cutting oil, including the use of ATF.

Cringe away! For God's sake., do not under any circumstances actually try using ATF.
Dan
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On Thursday, December 8, 2016 at 7:24:50 PM UTC-5, snipped-for-privacy@krl.org wrote:
e:

ar to me which types of lubrication are involved, but some lubricants not f ormulated for cutting (such as motor oil) can cause a cutting edge to skate over the work if the machine isn't sufficiently rigid or if the cut isn't sufficiently aggressive. This is why I cringe when people discuss cooking u p their own brews of cutting oil, including the use of ATF.

I don't use it on my lathe for the same reason I don't put sulfated cutting oil in my car's transmission.
--
Ed Huntress

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On Thursday, December 8, 2016 at 7:36:16 PM UTC-5, snipped-for-privacy@gmail.com wrote:

Ah. Tradition.
Dan
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On Friday, December 9, 2016 at 8:53:07 AM UTC-5, snipped-for-privacy@krl.org wrote:

Common sense.
--
Ed Huntress

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On Friday, December 9, 2016 at 9:04:58 AM UTC-5, snipped-for-privacy@gmail.com wrote:

If it were common sense, you would have tried ATF as a cutting lube and decided on how it performs. It is not as if trying ATF is ooing to contaminate the lathe. No it is tradition in your case.
Dan
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On Friday, December 9, 2016 at 2:09:06 PM UTC-5, snipped-for-privacy@krl.org wrote:

Why don't you just piss on it, Dan, and see how that performs?
And why buy ATF for an experiment when I already have real cutting oil that works?
--
Ed Huntress

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On Friday, December 9, 2016 at 2:19:02 PM UTC-5, snipped-for-privacy@gmail.com wrote:

ATF is a low viscosity lubricant good for high pressures and has good antir ust qualities. _Pretty much the properties needed for a cutting lubricant. And since it is used in millions of automobiles and sold almost everywhere . So it is inexpensive.
Piss on the other hand is cheaper, but is not good as a high pressure lubri cant. And it has no antirust properties. As a cutting fluid it would work for removing heat, but water is cheaper and is better as far as rust is co ncerned.

at works?

But since you have not used ATF as a cutting libricant, I contend you are n ot qualified to tell others that that it is not good. So keep using your r eal cutting oil, but why don't you quit saying it is not good for home shop machining. You admit you do not have any experience with it.
Dan

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On Friday, December 9, 2016 at 6:33:10 PM UTC-5, snipped-for-privacy@krl.org wrote:
:

irust qualities. _Pretty much the properties needed for a cutting lubrican t. And since it is used in millions of automobiles and sold almost everywhe re. So it is inexpensive.

ricant. And it has no antirust properties. As a cutting fluid it would wo rk for removing heat, but water is cheaper and is better as far as rust is concerned.

that works?

not qualified to tell others that that it is not good. So keep using your real cutting oil, but why don't you quit saying it is not good for home sh op machining. You admit you do not have any experience with it.

I know how experts have reacted when I mentioned that some home-shop machin ists use it. It gets an eye-roll.
ATF is a very complex formulation, formulated to do just about the opposite of what you want in a cutting oil. It has to maintain band friction, and t he high-pressure function is just about the opposite of what you want. You want high pressure tolerance with HIGH friction under high pressure, which is what you get, more or less, with sulfur and other additives. Otherwise, the tool can skate.
You don't know what you're talking about. It's almost certain that you've n ever done the instrumented tests on friction, tool load, tool wear, finish, and other tests that the real experts do.
So go use your rat-piss or whatever. It's your lathe. Just don't try to tel l us that you have a clue.
--
Ed Huntress

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On Friday, December 9, 2016 at 6:45:20 PM UTC-5, snipped-for-privacy@gmail.com wrote:
te:

ntirust qualities. _Pretty much the properties needed for a cutting lubric ant. And since it is used in millions of automobiles and sold almost everyw here. So it is inexpensive.

ubricant. And it has no antirust properties. As a cutting fluid it would work for removing heat, but water is cheaper and is better as far as rust i s concerned.

l that works?

re not qualified to tell others that that it is not good. So keep using yo ur real cutting oil, but why don't you quit saying it is not good for home shop machining. You admit you do not have any experience with it.

inists use it. It gets an eye-roll.

te of what you want in a cutting oil. It has to maintain band friction, and the high-pressure function is just about the opposite of what you want. Yo u want high pressure tolerance with HIGH friction under high pressure, whic h is what you get, more or less, with sulfur and other additives. Otherwise , the tool can skate.

never done the instrumented tests on friction, tool load, tool wear, finis h, and other tests that the real experts do.

ell us that you have a clue.

But if you have not used it , you are unqualified to comment.
I would not recommend using ATF in a commercial shop. A commercial shop i s probably using soluble oil which is mostly water.
Dan
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On Friday, December 9, 2016 at 7:03:16 PM UTC-5, snipped-for-privacy@krl.org wrote:
:
rote:

antirust qualities. _Pretty much the properties needed for a cutting lubr icant. And since it is used in millions of automobiles and sold almost ever ywhere. So it is inexpensive.

lubricant. And it has no antirust properties. As a cutting fluid it woul d work for removing heat, but water is cheaper and is better as far as rust is concerned.

oil that works?

are not qualified to tell others that that it is not good. So keep using your real cutting oil, but why don't you quit saying it is not good for hom e shop machining. You admit you do not have any experience with it.

chinists use it. It gets an eye-roll.

site of what you want in a cutting oil. It has to maintain band friction, a nd the high-pressure function is just about the opposite of what you want. You want high pressure tolerance with HIGH friction under high pressure, wh ich is what you get, more or less, with sulfur and other additives. Otherwi se, the tool can skate.

ve never done the instrumented tests on friction, tool load, tool wear, fin ish, and other tests that the real experts do.

tell us that you have a clue.

And you have done no engineering-quality comparison, so you might as well b e using tomato soup.

We're all happy to hear that, Dan.

As speeds go up and the machining environment becomes more demanding, you g o through several performance realms that demand different lubricating/cool ing fluids. At the high end, you neither need lubrication nor want cooling. Very high speed hard machining usually is done dry.
--
Ed Huntress




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