Awl--

Admittedly a pretty general Q, but here's the rationale/context:

I have observed that it is possible to take too lite of a finish cut, in
both side milling and face milling, and in turning.
I've forgotten the exact scenario, but something like .002-005 was too lite,
and .015-.020 seemed to have been much better.
Whatever the exact differences in the numbers were, the appearance was
strikingly different, in manual lathe work as well.

Are there any guidelines/rules of thumb for finish cuts?
For example, in milling, on alum or unhardened 4140, using insert face mills
or 4 flute em sidemilling. Also in turning.
--
------
Mr. P.V.'d (formerly Droll Troll), Yonkers, NY

Stop Corruption in Congress & Send the Ultimate Message:
Absolutely Vote, but NOT for a Democrat or a Republican.
Ending Corruption in Congress is the *Single Best Way*
to Materially Improve Your Family's Life.
The Solution is so simple--and inexpensive!

entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie,
all d'numbuhs

"Proctologically Violated©®" wrote in
message ...
I have observed that it is possible to take too lite of a finish cut, in
both side milling and face milling, and in turning.
I've forgotten the exact scenario, but something like .002-005 was too
lite, and .015-.020 seemed to have been much better.
Whatever the exact differences in the numbers were, the appearance was
strikingly different, in manual lathe work as well.

That really depends upon the metal, your tool geometry, and the tool's
degree of polish.

I usually DO take less than half-a-thou on the last cut; normally, just for
cosmetics, but also for close fit-ups.

Really light passes, just pulling black swarf, require that everything be
very, very rigid. Take up all the lost motion everywhere, make sure your
spindle bearings are at the right preload, and snug up every gib. (and don't
forget all your feed screws' loading nuts, if you don't intend to lock a
particular axis.)

LLoyd

To summarize what Lloyd sez:

Be sure the width of "finish" chips is less than the depth of chatter.

Bob Swinney

"Lloyd E. Sponenburgh" wrote in message
...

"Proctologically Violated©®" wrote in
message ...
I have observed that it is possible to take too lite of a finish cut, in
both side milling and face milling, and in turning.
I've forgotten the exact scenario, but something like .002-005 was too
lite, and .015-.020 seemed to have been much better.
Whatever the exact differences in the numbers were, the appearance was
strikingly different, in manual lathe work as well.

That really depends upon the metal, your tool geometry, and the tool's
degree of polish.

I usually DO take less than half-a-thou on the last cut; normally, just for
cosmetics, but also for close fit-ups.

Really light passes, just pulling black swarf, require that everything be
very, very rigid. Take up all the lost motion everywhere, make sure your
spindle bearings are at the right preload, and snug up every gib. (and don't
forget all your feed screws' loading nuts, if you don't intend to lock a
particular axis.)

LLoyd

"Proctologically Violated©®" wrote in
message ...
Awl--

Admittedly a pretty general Q, but here's the rationale/context:

I have observed that it is possible to take too lite of a finish cut, in
both side milling and face milling, and in turning.
I've forgotten the exact scenario, but something like .002-005 was too
lite,
and .015-.020 seemed to have been much better.
Whatever the exact differences in the numbers were, the appearance was
strikingly different, in manual lathe work as well.

Are there any guidelines/rules of thumb for finish cuts?
For example, in milling, on alum or unhardened 4140, using insert face
mills
or 4 flute em sidemilling. Also in turning.
--

A lot of this depends on the rigidity of the machine and the tool geometry.
The looser the machine the more careful you have to be as there is less
pressure taking up the flex with a lighter cut.

Most of the machines I have worked on have been clunkers, so before I get to
size I will play a bit to get the balance right. In school they had a nice
Hardinge, and that machine was a dream to run.

I have noticed that a better finish is obtained when the bit is ground with
a bit of a radius and there is a little rub on the face of the bit. The
down side to this geometry is that you can't hog away as much. I suspect
this is because the tool bit is retaining more heat that would be ordinarily
carried away in the chips.

The bugger is when relying on the tool geometry to spring the cutter back a
bit to take up the slack and the spring, is what happens when you are ending
the cut. It can be a bit tricky to stop the feed and back off the pressure
before the cutter reduces the size of the work at the end of cut. This is
when it would be really nice to have three or four hands.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

"Roger Shoaf" wrote in message
...
I have noticed that a better finish is obtained when the bit is ground
with
a bit of a radius and there is a little rub on the face of the bit. The
down side to this geometry is that you can't hog away as much. I suspect
this is because the tool bit is retaining more heat that would be
ordinarily
carried away in the chips.

At a few tenths of cutting depth, even a "sharp cornered" tool can be given
enough radius with a couple of quick licks with an Arkansas hard-stone.

Don't forget that your workpiece finish cannot be any finer than the finish
on the tool. A burred-up tool face with visible grinding marks gives a
burred-up finish. Attack a job with a rasp, and it'll LOOK like it was
attacked with a rasp G.

The less tool surface contacting the work, the narrower the chip; and thus,
the less pressure and horsepower to cut. Less pressure means less spring in
the works. Less spring means better finish with a less rigid machine.

Unless the material really needs a lot of rake to cut cleanly, I get my
nicest burnishing cuts with approximately zero back and side rake, a very
broad radius on the tool (I know; contrary to what I wrote above), a mirror
polish on its edge, and the finest feed I can set -- or endure.

'Course, the width of the chip has to be greater than the feed, or you'll
have to make numerous passes, polishing off the "highs" with successive
cuts. (and not changing anything about the setup) Basically, repeating the
process until it no longer moves any metal.

LLoyd

"Proctologically Violated©®" wrote in
message ...
Awl--

Admittedly a pretty general Q, but here's the rationale/context:

I have observed that it is possible to take too lite of a finish cut, in
both side milling and face milling, and in turning.
I've forgotten the exact scenario, but something like .002-005 was too
lite,
and .015-.020 seemed to have been much better.
Whatever the exact differences in the numbers were, the appearance was
strikingly different, in manual lathe work as well.

Are there any guidelines/rules of thumb for finish cuts?
For example, in milling, on alum or unhardened 4140, using insert face
mills
or 4 flute em sidemilling. Also in turning.


Suggest quit with crossposting this kinda ****--( already more than enough
fruit loops in the bowl as it is )

--

On Aug 9, 6:53 am, "Proctologically Violated©®"
wrote:
Awl--

Admittedly a pretty general Q, but here's the rationale/context:

I have observed that it is possible to take too lite of a finish cut, in
both side milling and face milling, and in turning.
I've forgotten the exact scenario, but something like .002-005 was too lite,
and .015-.020 seemed to have been much better.
Whatever the exact differences in the numbers were, the appearance was
strikingly different, in manual lathe work as well.

Are there any guidelines/rules of thumb for finish cuts?
For example, in milling, on alum or unhardened 4140, using insert face mills
or 4 flute em sidemilling. Also in turning.
--
------
Mr. P.V.'d (formerly Droll Troll), Yonkers, NY

Stop Corruption in Congress & Send the Ultimate Message:
Absolutely Vote, but NOT for a Democrat or a Republican.
Ending Corruption in Congress is the *Single Best Way*
to Materially Improve Your Family's Life.
The Solution is so simple--and inexpensive!

entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie,
all d'numbuhs

"You can't get a better finish on your part than what's ground into
your end mill."

Reference: Bud Darling, San Fernando Valley Circa 1974.
He had worked in 52 shops in 25 years. What an exposure he had.
My Hero. Only met him once in ''74. I learned more that evening
than any time afterwards in a the few hours we had.

He also said climb accross, conventional back. One: this gives you an
automatic finish pass.
Two: You can cut with more surface speed while climb cutting because
the heat is being forced back into the body of the part. In
conventional cutting as the cutter exits the edge of the part the heat
concentrates in the thin edge and turns it dark. This is hard on
cutter life.

Regards,

Stan-

"Proctologically Violated©®"
wrote in :

Admittedly a pretty general Q, but here's the rationale/context:

I have observed that it is possible to take too lite of a finish cut,
in both side milling and face milling, and in turning.
I've forgotten the exact scenario, but something like .002-005 was too
lite, and .015-.020 seemed to have been much better.
Whatever the exact differences in the numbers were, the appearance was
strikingly different, in manual lathe work as well.

Are there any guidelines/rules of thumb for finish cuts?
For example, in milling, on alum or unhardened 4140, using insert face
mills or 4 flute em sidemilling. Also in turning.

In turning 60% of the inserts nose radius is bare minimum as a "rule of
thumb".

In milling it doesn't matter provided you've got a good end mill and enough
rpm and feedrate. But you'll need to trade in the Fadal and buy a CAM
system.

http://toolingandproduction.com/archives/0198/0198mill.html

--

Dan

CNC Videos - http://tinyurl.com/yzdt6d

On Thu, 9 Aug 2007 13:47:51 -0400, "Lloyd E. Sponenburgh"
wrote:

Don't forget that your workpiece finish cannot be any finer than the finish
on the tool.

Yes it can. Or worse.

For a simple example of yes look at a grinding wheel's
surface finish then at the surface finish it produces.
--
Cliff

On Thu, 9 Aug 2007 13:47:51 -0400, "Lloyd E. Sponenburgh"
wrote:

The less tool surface contacting the work, the narrower the chip; and thus,
the less pressure and horsepower to cut.

Feedrate matters.
--
Cliff

On Thu, 9 Aug 2007 13:47:51 -0400, "Lloyd E. Sponenburgh"
wrote:

Unless the material really needs a lot of rake to cut cleanly, I get my
nicest burnishing cuts with approximately zero back and side rake, a very
broad radius on the tool (I know; contrary to what I wrote above), a mirror
polish on its edge, and the finest feed I can set -- or endure.

A "burnished" surface may look pretty but you've just wiped/smeared
the high spots into the low ones, usually. Though you can also (with a
burnishing tool & the proper process & material) cause the high spots to
"flow" "downwards" & the low ones to flow up & fill in.
--
Cliff

On Thu, 9 Aug 2007 13:47:51 -0400, "Lloyd E. Sponenburgh"
wrote:

'Course, the width of the chip has to be greater than the feed,

??
--
Cliff

"D Murphy" wrote in message
...
"Proctologically Violated©®"

wrote in :

But you'll need to trade in the Fadal and buy a CAM system.


Why would one need a CAM system to control finish depth of cut?
Couldn't tool comp be utilized?

"Cliff" wrote in message
...
On Thu, 9 Aug 2007 13:47:51 -0400, "Lloyd E. Sponenburgh"
wrote:
Yes it can. Or worse.

For a simple example of yes look at a grinding wheel's
surface finish then at the surface finish it produces.

Invalid argument. A wheel has an essentially infinite number of cutting
edges, all (eventually) playing at the same cutting depth. A tool bit has a
single cutting edge, whose cutting-plane defects will telegraph to the work.

Sure, with an infinite number of cuts at an infinite number of starting
positions, even a rough tool can give a smooth finish.

(chatter doesn't count in this discussion -- you're supposed to have
eliminated all that before the tool finish becomes important)

LLoyd

"Metalcutter" wrote in message
ups.com...
"You can't get a better finish on your part than what's ground into
your end mill."

..... heh! Where'd I hear something like THAT before ? G

He also said climb accross, conventional back. One: this gives you an
automatic finish pass.

..... yup... but there's a "yeahbut" in there. Yeah, but a lot of the cheap
machines built of grey-colored jello (and old, worn machines) have so much
flex and slop that conventional won't allow you to hold a dimension. So,
many rec. machinists end up climbing on all cuts, lest they over cut or
chatter the hell out of the surface.

Gotta have near-perfect rigidity to do it right.

LLoyd

On Aug 10, 4:41 am, "Lloyd E. Sponenburgh"
wrote:
"Metalcutter" wrote in message

ups.com...
"You can't get a better finish on your part than what's ground into
your end mill."

.... heh! Where'd I hear something like THAT before ? G

He also said climb accross, conventional back. One: this gives you an
automatic finish pass.

.... yup... but there's a "yeahbut" in there. Yeah, but a lot of the cheap
machines built of grey-colored jello (and old, worn machines) have so much
flex and slop that conventional won't allow you to hold a dimension. So,
many rec. machinists end up climbing on all cuts, lest they over cut or
chatter the hell out of the surface.

Gotta have near-perfect rigidity to do it right.

LLoyd

I've always had good luck with it LLoyd.

But then my experience is fairly narrow and limited to Blue Hurcos and
an Index mill. :-)
I've never run BIG stuff.

The theory was: The climb cut would stress the tool and machine away
from the part and then when coming back on the same setting the tool
and machine would relax; and that small movement would allow for a
finish cut. Hand mill stuff.

As for CNC-ing I usually just run the same path again after the
roughing cut. That usually puts me within .001-.002 of where I want
to be.

Regards,

Stan-

"Proctologically Violated©®" wrote:

I have observed that it is possible to take too lite of a finish cut, in
both side milling and face milling, and in turning.
I've forgotten the exact scenario, but something like .002-005 was too lite,
and .015-.020 seemed to have been much better.
Whatever the exact differences in the numbers were, the appearance was
strikingly different, in manual lathe work as well.

On a real machine 0.020 to 0.030 is a finishing cut. Many on r.c.m have
light machines where that is roughing and due to the rigidity of the machine
they tend to burnish the part to size.

Wes

"Bart" bborb@fusedotnet wrote in news:1b23e$46bc4760$d8444218$20689
@FUSE.NET:


"D Murphy" wrote in message
...
"Proctologically Violated©®"

wrote in :

But you'll need to trade in the Fadal and buy a CAM system.


Why would one need a CAM system to control finish depth of cut?
Couldn't tool comp be utilized?



The link was to a high speed machining article. HSM is hard to pull off
without the proper software.

--

Dan

CNC Videos - http://tinyurl.com/yzdt6d

On Aug 10, 11:06 am, Metalcutter wrote:
On Aug 10, 4:41 am, "Lloyd E. Sponenburgh"
wrote:





"Metalcutter" wrote in message

oups.com...
"You can't get a better finish on your part than what's ground into
your end mill."

.... heh! Where'd I hear something like THAT before ? G

He also said climb accross, conventional back. One: this gives you an
automatic finish pass.

.... yup... but there's a "yeahbut" in there. Yeah, but a lot of the cheap
machines built of grey-colored jello (and old, worn machines) have so much
flex and slop that conventional won't allow you to hold a dimension. So,
many rec. machinists end up climbing on all cuts, lest they over cut or
chatter the hell out of the surface.

Gotta have near-perfect rigidity to do it right.

LLoyd

I've always had good luck with it LLoyd.

But then my experience is fairly narrow and limited to Blue Hurcos and
an Index mill. :-)
I've never run BIG stuff.

The theory was: The climb cut would stress the tool and machine away
from the part and then when coming back on the same setting the tool
and machine would relax; and that small movement would allow for a
finish cut. Hand mill stuff.

As for CNC-ing I usually just run the same path again after the
roughing cut. That usually puts me within .001-.002 of where I want
to be.

Regards,

Stan-- Hide quoted text -

- Show quoted text -

You sure of that sequence? I've found that the reverse is usually
preferable.

You typically get better finishes from a light climb cut than from a
light conventional cut. With a conventional cut, the chip goes from
thin to thick, and the cutter may skid on the surface until there is
enough pressure and depth to get it to start taking a chip. With a
climb cut, the chip goes from thick to thin, and the cutter is cutting
from the start.

The problem with climb cutting is that it requires more machine
rigidity and less slop in the feed screws. And tight gibs. On my
horizontal mill, I can take a heavy conventional cut, but anything
more than a very light climb cut will try to pull the table along.
Not good.

So, for me, it's a heavy conventional cut followed by a light climb
cut.

Same thing with woodworking, but for somewhat different reasons. A
conventional cut tends to pull fibers up out of the surface, a climb
cut does not. But you don't want to try one with a router or shaper
unless it is a very light cut, unless the work is controlled by a
stock feeder.

Just my $.02 worth. Anyone else?

John Martin

On Aug 11, 8:56 am, John Martin wrote:
On Aug 10, 11:06 am, Metalcutter wrote:





On Aug 10, 4:41 am, "Lloyd E. Sponenburgh"
wrote:

"Metalcutter" wrote in message

oups.com...
"You can't get a better finish on your part than what's ground into
your end mill."

.... heh! Where'd I hear something like THAT before ? G

He also said climb accross, conventional back. One: this gives you an
automatic finish pass.

.... yup... but there's a "yeahbut" in there. Yeah, but a lot of the cheap
machines built of grey-colored jello (and old, worn machines) have so much
flex and slop that conventional won't allow you to hold a dimension. So,
many rec. machinists end up climbing on all cuts, lest they over cut or
chatter the hell out of the surface.

Gotta have near-perfect rigidity to do it right.

LLoyd

I've always had good luck with it LLoyd.

But then my experience is fairly narrow and limited to Blue Hurcos and
an Index mill. :-)
I've never run BIG stuff.

The theory was: The climb cut would stress the tool and machine away
from the part and then when coming back on the same setting the tool
and machine would relax; and that small movement would allow for a
finish cut. Hand mill stuff.

As for CNC-ing I usually just run the same path again after the
roughing cut. That usually puts me within .001-.002 of where I want
to be.

Regards,

Stan-- Hide quoted text -

- Show quoted text -

You sure of that sequence? I've found that the reverse is usually
preferable.

You typically get better finishes from a light climb cut than from a
light conventional cut. With a conventional cut, the chip goes from
thin to thick, and the cutter may skid on the surface until there is
enough pressure and depth to get it to start taking a chip. With a
climb cut, the chip goes from thick to thin, and the cutter is cutting
from the start.

The problem with climb cutting is that it requires more machine
rigidity and less slop in the feed screws. And tight gibs. On my
horizontal mill, I can take a heavy conventional cut, but anything
more than a very light climb cut will try to pull the table along.
Not good.

So, for me, it's a heavy conventional cut followed by a light climb
cut.

Same thing with woodworking, but for somewhat different reasons. A
conventional cut tends to pull fibers up out of the surface, a climb
cut does not. But you don't want to try one with a router or shaper
unless it is a very light cut, unless the work is controlled by a
stock feeder.

Just my $.02 worth. Anyone else?

John Martin- Hide quoted text -

- Show quoted text -

It's worked for me John.

No my work if the table starts running ahead I just tighten the table
brake to just eliminate it.

Most of my equipment isn't all that worn though.

Thanks for the reply,

Stan-

On Thu, 9 Aug 2007 09:53:52 -0400, "Proctologically Violated©®"
wrote:


I have observed that it is possible to take too lite of a finish cut, in
both side milling and face milling, and in turning.
I've forgotten the exact scenario, but something like .002-005 was too lite,
and .015-.020 seemed to have been much better.

Im afraid there are no cut and dried answers to this one.

It largely depends on material, cutter type and material, rake, relief
and so forth. As well as machine rigidity, vibration, rpm etc etc

HSS "properly ground" will allow you to more often make a .0005
cut..than will carbide in more materials than will carbide. YMMV

And it depends on what finish you want..a 16 or an 8 G

Based on my interaction in machine shops..one has to experiement a
bit..or be a really experienced machinist who has used the particular
machine and material combo before.

Shrug

Gunner, waiting for the flames

Gunner Asch wrote:

It largely depends on material, cutter type and material, rake, relief
and so forth. As well as machine rigidity, vibration, rpm etc etc

I second that and extend:
* coolant or cutting oil or dry cutting
* lubrication of lathe's bed and feed spindle.
* spindle temperature
* slightly clamping the saddle or not

and and an. It is not just the tool!

Re material:
I have some round (thanks good almost used up) that is nice to turn the
first mm, then there comes a region of 1mm that is a pain and then it gets
nice again.

Nick

Proctologically Violated©® wrote:
Awl--

Admittedly a pretty general Q, but here's the rationale/context:

I have observed that it is possible to take too lite of a finish cut, in
both side milling and face milling, and in turning.
I've forgotten the exact scenario, but something like .002-005 was too lite,
and .015-.020 seemed to have been much better.
Whatever the exact differences in the numbers were, the appearance was
strikingly different, in manual lathe work as well.
I generally use .010" as my default, and rarely have to change
it. On rare occasions I have to go up, as the roughing pass in
a slot wanders more than that due to tool deflection. Probably
doing too deep a Z step on that one. This seems to work quite
well for me. It might be machine dependent, as well as tool and
workpiece material.

Jon

John Martin wrote:
On Aug 10, 11:06 am, Metalcutter wrote:

On Aug 10, 4:41 am, "Lloyd E. Sponenburgh"
wrote:

He also said climb accross, conventional back. One: this gives you an
automatic finish pass.

You sure of that sequence? I've found that the reverse is usually
preferable.

You typically get better finishes from a light climb cut than from a
light conventional cut. With a conventional cut, the chip goes from
thin to thick, and the cutter may skid on the surface until there is
enough pressure and depth to get it to start taking a chip. With a
climb cut, the chip goes from thick to thin, and the cutter is cutting
from the start.
Yes, I agree completely. I do as much climb milling as
possible, now that I have a pretty rigid CNC machine with
ballscrews. I get better tool life and much smoother finish.
I used to always finish with a climb cut on my manual machine as
it gave a better finish, and a light climb cut would not cause
the table to jump toward the work.

Jon