Just for the experience, I tried cutting a 0.625" diameter brass rod off
with a BXA-7 cutoff tool, both dry and wet, even though all the books
say that brass is best cut dry.

Dry, it squealed loudly but cut nicely at ~800 rpm, yielding random
piles of little brass needles as long as the cutoff blade was wide.

Wet with oil emulsion (Rustlick WS-5050), it squealed very quietly at
the same speed, but yielded mirror surfaces. The wet piles of little
brass needles sitting on the top of the cutoff blade were not random,
instead looking like stacked firewood, and the needles ended up in neat
piles rather than going everywhere.

A better lubricant might eliminate the brass squeal entirely. Steel cut
off in the same setup does not squeal at all.

So, cutting brass wet actually helps, at least with an oil emulsion.
This ties in with the historical use of whole milk as a cutting fluid
for brass and copper, milk being an emulsion of butterfat in water.

At least WS-5050 doesn't turn rancid.

Joe Gwinn

Lots of non-recommended methods work, just not quite as well as the
recommended ones. Often for one-off jobs it doesn't matter. The
Cincinatti "Milling & Milling Machines" book from Lindsay describes
cutting speed and coolant tests on cast iron, for example. There
wasn't much difference with or without oil, so they suggested milling
dry to avoid the mess (pp. 123-4). Textbooks present that as a hard
rule with no explanation.

I start with the same cutting oil on everything including aluminum and
brass and only change to the recommended fluid when there's a problem
that sharpening the bit doesn't solve, which isn't often.

Jim Wilkins

In article
,
Jim Wilkins wrote:

Lots of non-recommended methods work, just not quite as well as the
recommended ones. Often for one-off jobs it doesn't matter.

Umm. I'm reporting that cutting wet (a non-recommended method) in fact
works a lot better than cutting dry (the recommended method).


The Cincinatti "Milling & Milling Machines" book from Lindsay describes
cutting speed and coolant tests on cast iron, for example. There
wasn't much difference with or without oil, so they suggested milling
dry to avoid the mess (pp. 123-4). Textbooks present that as a hard
rule with no explanation.

I have not read this book, I think. I'll have to check.

My report is about brass, not cast iron, but I did read somewhere that
some companies cut cast iron wet to keep the iron dust under control.
Apparently the wet mess was less a problem than the dry mess. Or at
least the mess stays in one place, and doesn't get into everything.
With flood cooling and a filter, the problem would certainly be
controlled.


I start with the same cutting oil on everything including aluminum and
brass and only change to the recommended fluid when there's a problem
that sharpening the bit doesn't solve, which isn't often.

I'm certainly going this way. I have yet to run the experiment on cast
iron, but I will. But it may not be soon, as have to get some cast iron
first.


Joe Gwinn

In article ,
"Robert Swinney" wrote:

Right on, Jim. The "dry brass" rule is amended esp. for cutting off
(parting) in most of Sherline's literature.

Good to know.


It doesn't seem to make a lot of difference when working with small stuff;
but real cutting fluid such as Tap Matic is best. Just about any oily fluid is much
better than nothing at all when cutting off brass.

Oddly, I found that the WS-5050 oil emulsion makes a pretty good
lubricant for hand tapping, actually working better than LPS Tap-All.
And I have gallons of WS-5050 emulsion, which is cheap enough to use
once and discard.

Does Tap Matic work better than Tap-All?

Joe Gwinn


Bob Swinney

"Jim Wilkins" wrote in message
...
Lots of non-recommended methods work, just not quite as well as the
recommended ones. Often for one-off jobs it doesn't matter. The
Cincinatti "Milling & Milling Machines" book from Lindsay describes
cutting speed and coolant tests on cast iron, for example. There
wasn't much difference with or without oil, so they suggested milling
dry to avoid the mess (pp. 123-4). Textbooks present that as a hard
rule with no explanation.

I start with the same cutting oil on everything including aluminum and
brass and only change to the recommended fluid when there's a problem
that sharpening the bit doesn't solve, which isn't often.

Jim Wilkins

On Jun 5, 5:01*pm, Joseph Gwinn wrote:
In article
,
*Jim Wilkins wrote:

The Cincinatti "Milling & Milling Machines" book from Lindsay describes
cutting speed and coolant tests on cast iron, for example. There
wasn't much difference with or without oil, so they suggested milling
dry to avoid the mess (pp. 123-4). Textbooks present that as a hard
rule with no explanation.

I have not read this book, I think. *I'll have to check.

My report is about brass, not cast iron, but I did read somewhere that
some companies cut cast iron wet to keep the iron dust under control. *
Apparently the wet mess was less a problem than the dry mess. *Or at
least the mess stays in one place, and doesn't get into everything. *
With flood cooling and a filter, the problem would certainly be
controlled.

Joe Gwinn

The 1919 book said that coolant stopped heat distortion of odd-shaped
or fragile parts but the grit damaged machine bearings. I don't cut
fast or deep enough to overheat the tool or work and a little oil (or
tapping fluid) from a brush or needle oiler seems to be enough. Maybe
my old, slow, worn machines mask effects that would be important for
more aggressive cuts on newer ones.

Jim Wilkins

In article
,
Jim Wilkins wrote:

On Jun 5, 5:01*pm, Joseph Gwinn wrote:
In article
,
*Jim Wilkins wrote:

The Cincinatti "Milling & Milling Machines" book from Lindsay describes
cutting speed and coolant tests on cast iron, for example. There
wasn't much difference with or without oil, so they suggested milling
dry to avoid the mess (pp. 123-4). Textbooks present that as a hard
rule with no explanation.

I have not read this book, I think. *I'll have to check.

My report is about brass, not cast iron, but I did read somewhere that
some companies cut cast iron wet to keep the iron dust under control. *
Apparently the wet mess was less a problem than the dry mess. *Or at
least the mess stays in one place, and doesn't get into everything. *
With flood cooling and a filter, the problem would certainly be
controlled.

The 1919 book said that coolant stopped heat distortion of odd-shaped
or fragile parts but the grit damaged machine bearings. I don't cut
fast or deep enough to overheat the tool or work and a little oil (or
tapping fluid) from a brush or needle oiler seems to be enough. Maybe
my old, slow, worn machines mask effects that would be important for
more aggressive cuts on newer ones.

My recollection is that the book that suggested wet cutting of cast iron
said that it didn't improve the machining, but the iron dust in the
factory got into everything, man and machine alike, and was very
annoying, in the same manner as sand in a sandstorm. The sole reason
given to cut wet was to trap the dust.

As for the grit getting into the bearings, that sounds like a machine
design issue either way. The flow of air or fluid should be arranged to
move the grit away from critical areas.

I've been using a Noga mister on the lathe, mainly so I don't get blue
emulsion flung everywhere. The drill press is set up for flood cooling
with the same emulsion. The problem with misters is that breathing the
mist doesn't feel good, so I wear a 3M dust and mist mask.

Joe Gwinn

On Jun 5, 10:00*pm, Joseph Gwinn wrote:

As for the grit getting into the bearings, that sounds like a machine
design issue either way. *The flow of air or fluid should be arranged to
move the grit away from critical areas.

Joe Gwinn

The machine designers didn't have synthetic rubber for seals in 1919.
Some of our old home machines may have the same concerns. My 1965
South Bend lathe is an update of a 1920's model.

I read their long discussions to mean that a little lubricant is
enough to improve surface finish and a flood of any cheap coolant
greatly improves high speed production. For intermediate amounts, "The
average small stream as usually provided, is by no means sufficient to
secure ample cooling."
The book contains many observations and test results but generally
expects the reader to decide how to apply them.

Jim Wilkins

I'm milling the semicircular radius on sheet metal brake hinges on a
rotary table. Milling the steel dry is giving me a better finish than
a little oil does as long as I hold a brush on the back side of the
end mill to remove adhering slivers.

Jim Wilkins

In article
,
Jim Wilkins wrote:

I'm milling the semicircular radius on sheet metal brake hinges on a
rotary table. Milling the steel dry is giving me a better finish than
a little oil does as long as I hold a brush on the back side of the
end mill to remove adhering slivers.

I've had the same experience with brushed oil. The problem is that the
oil keeps the chips in the action. A mister with enough airflow to blow
the chips away yields a considerable improvement, as does copious flood
cooling.

Joe Gwinn

On Jun 8, 11:57*am, Joseph Gwinn wrote:
I've had the same experience with brushed oil. *The problem is that the
oil keeps the chips in the action. *A mister with enough airflow to blow
the chips away yields a considerable improvement, as does copious flood
cooling.

Joe Gwinn

They do, on machines made for it. The tee slots on my Clausing are
open-ended and no way do I want the curved slivers from cutting with
the side of an end mill blown on the floor, then tracked upstairs, and
permanently stuck in the rug.

In article
,
Jim Wilkins wrote:

On Jun 8, 11:57*am, Joseph Gwinn wrote:
I've had the same experience with brushed oil. *The problem is that the
oil keeps the chips in the action. *A mister with enough airflow to blow
the chips away yields a considerable improvement, as does copious flood
cooling.

Joe Gwinn

They do, on machines made for it. The tee slots on my Clausing are
open-ended and no way do I want the curved slivers from cutting with
the side of an end mill blown on the floor, then tracked upstairs, and
permanently stuck in the rug.

The curved slivers are a real problem.

Make some endplates, one with a drain fitting, and use flood coolant?

Joe Gwinn

On Jun 8, 12:56*pm, Joseph Gwinn wrote:
...
Make some endplates, one with a drain fitting, and use flood coolant?
Joe Gwinn

I have been alternately welding steel onto the hinges and milling most
of it off again all day with maybe a drop of oil a minute brushed on
when the smoke lightens up. And it works fine that way. The finish is
good enough for the purpose and I haven't had to resharpen this end
mill in 3 years. (The tips are beveled and they don't wear down nearly
as fast as sharp ones.)

If the mill had automatic feed it would need an automatic way to apply
oil but it doesn't, I have to be there anyway to turn the crank, so
brushing on oil with the free hand is entirely practical.

In article
,
Jim Wilkins wrote:

On Jun 8, 12:56*pm, Joseph Gwinn wrote:
...
Make some endplates, one with a drain fitting, and use flood coolant?
Joe Gwinn

I have been alternately welding steel onto the hinges and milling most
of it off again all day with maybe a drop of oil a minute brushed on
when the smoke lightens up. And it works fine that way. The finish is
good enough for the purpose and I haven't had to resharpen this end
mill in 3 years. (The tips are beveled and they don't wear down nearly
as fast as sharp ones.)

If the mill had automatic feed it would need an automatic way to apply
oil but it doesn't, I have to be there anyway to turn the crank, so
brushing on oil with the free hand is entirely practical.

I do have power feed, but the issue is surface finish. If I'm looking
for pretty, chip removal is necessary. But if surface finish isn't
important, then brushing or hand squirting works.

I have been using coolant in a hand squirt bottle with some success, as
it allows me to get coolant into places hard to reach with a brush.

Joe Gwinn

On Jun 9, 9:04*am, Joseph Gwinn wrote:
...
I have been using coolant in a hand squirt bottle with some success, as
it allows me to get coolant into places hard to reach with a brush.

Joe Gwinn

To see what would happen I started drilling the hinge pin and the
sleeve around it without oil. The sleeve is annealed water pipe and
drilled like butter without oil, but the drill bit demanded oil for
the O-1 hinge pin.

Jim Wilkins