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I recently purchased a 7 x 12 mini lathe, and so far it has been
wonderful, I am very satisfied. I purchased a quick change tool
holder from HF, and with a modification to the compound, now have
easy tool height adjustment. The only tool I have problems with is
the cut off tool.

I am using a .062" x .5" HSS tool, cutting brass and Aluminum. I
always seem to get terrible chatter. I made sure the saddle, cross
slide and compound are very tight to the ways, but it still happens.
Does anyone have any suggestions to make this better? I've not heard
of anyone else complain about this, so I think it must be something I
am doing.

Thanks for your help,
WD

WD
How big a diameter are you trying to part off? A lot of people
have difficulties with this. It gets dicey on my 7x12 on anything
more than 1-1/8" in diameter. I seem to get the best results
slowing the rpms way down, as low as I can go with the speed
control. Also, I make sure I have as little of the parting tool
as possible hanging out from the tool holder.
B Flint


--- In 7x12minilathe@..., "wdannhardt <wdannhardt@y...>"
<wdannhardt@y...> wrote:

The only tool I have problems with is
the cut off tool.

I am using a .062" x .5" HSS tool, cutting brass and Aluminum. I
always seem to get terrible chatter. I made sure the saddle, cross
slide and compound are very tight to the ways, but it still

happens.

Does anyone have any suggestions to make this better?
I've not heard of anyone else complain about this, so I think it
must be something I am doing.

WD

I've had similar problems. First make sure the "T" type parting tool
is absolutely perpendicular to the work because that type tool has no
side relief. Try lowering the tool a few thousandths below center.

A tool ground from square stock (a lot of grinding) with side reliefs
tends to work better for me, but has some limitation on cutting depth.

Parting off is, to me, difficult and slowing the lathe down as is
necessary for such operations reduces motor power.

Craig

--- In 7x12minilathe@..., "bbftx <bflint@a...>"
<bflint@a...> wrote:

WD
How big a diameter are you trying to part off? A lot of people
have difficulties with this. It gets dicey on my 7x12 on anything
more than 1-1/8" in diameter. I seem to get the best results
slowing the rpms way down, as low as I can go with the speed
control. Also, I make sure I have as little of the parting tool
as possible hanging out from the tool holder.
B Flint


--- In 7x12minilathe@..., "wdannhardt <wdannhardt@y...>"
<wdannhardt@y...> wrote:

The only tool I have problems with is
the cut off tool.

I am using a .062" x .5" HSS tool, cutting brass and Aluminum. I
always seem to get terrible chatter. I made sure the saddle,

cross

slide and compound are very tight to the ways, but it still

happens.

Does anyone have any suggestions to make this better?
I've not heard of anyone else complain about this, so I think it
must be something I am doing.

WD

How far from the chuck are you attempting to part off? You should be
working as close to the chuck as possible (like less than one diameter.)

One concern I have about those quick change tool posts is that they put the
tool way out to the side of the cross-slide/compound instead of centered
over the dovetails as would be Ideal (the downward force of cutting tends to
rock the cross-slide/compound to the side.) So if all else fails I guess
I am recommending turning the compound to 90 degrees from the cross slide
and backing it up for maximum engagement of the dovetails.

Some recommend parting from the rear with an upside down parting tool. On
the 7x10 you can try this from the front, you need an inverted tool holder
then just put the lathe in reverse. I made a parting tool holder for mine
and have tried it both ways but didn't see much difference (it works ok
either way.)

regards
Bob

I have the HF QCTP and have had the same problem. As others have
stated slow speed is an answer. I have even turned off the lathe and
turned the chuck by hand while feeding the cross slide, it worked
very well, much better than you might think.

HTH

Al Day


--- In 7x12minilathe@..., "wdannhardt <wdannhardt@y...>"
<wdannhardt@y...> wrote:

I recently purchased a 7 x 12 mini lathe, and so far it has been
wonderful, I am very satisfied. I purchased a quick change tool
holder from HF, and with a modification to the compound, now have
easy tool height adjustment. The only tool I have problems with is
the cut off tool.

I am using a .062" x .5" HSS tool, cutting brass and Aluminum. I
always seem to get terrible chatter. I made sure the saddle, cross
slide and compound are very tight to the ways, but it still

happens. WD

I tend to use the cutoff tool only for stock 1/2" dia.
or less. For bigger stuff, I use the bandsaw.

Frank Hoose


--- "Craig C. Hopewell
<chopewel@...>"
<chopewel@...> wrote:

I've had similar problems. First make sure the "T"
type parting tool
is absolutely perpendicular to the work because that
type tool has no
side relief. Try lowering the tool a few
thousandths below center.

A tool ground from square stock (a lot of grinding)
with side reliefs
tends to work better for me, but has some limitation
on cutting depth.

Parting off is, to me, difficult and slowing the
lathe down as is
necessary for such operations reduces motor power.

Craig

--- In 7x12minilathe@..., "bbftx
<bflint@a...>"
<bflint@a...> wrote:

WD
How big a diameter are you trying to part off? A

lot of people

have difficulties with this. It gets dicey on my

7x12 on anything

more than 1-1/8" in diameter. I seem to get the

best results

slowing the rpms way down, as low as I can go with

the speed

control. Also, I make sure I have as little of

the parting tool

as possible hanging out from the tool holder.
B Flint


--- In 7x12minilathe@..., "wdannhardt

<wdannhardt@y...>"

<wdannhardt@y...> wrote:

The only tool I have problems with is
the cut off tool.

I am using a .062" x .5" HSS tool, cutting brass

and Aluminum. I

always seem to get terrible chatter. I made

sure the saddle,
cross

slide and compound are very tight to the ways,

but it still

happens.

Does anyone have any suggestions to make this

better?

I've not heard of anyone else complain about

this, so I think it

must be something I am doing.

WD

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Parting problems are a recurring issue; you've happened to hit a
temporary lull :-)
Make sure the tool is truly vertical - my HF holder needed some
shimming to properly hold a "T" blade. It also has to be
perpendicular to the work, & has to stay that way - my HF QC post
tries to rotate around the mounting bolt.
The tool needs to be honed sharp and exactly on center. When
they're low, they cut beautifully, right up until the work climbs the
tool! Also, a carriage lock helps; using the half-nuts on the
leadscrew is not really solid enough. Low speed helps; you want a
continuous chip, so slow, steady feed & low spindle speed.
Rear parting lets the tool stay mounted (I swear they remount at
different heights due to fat air molecules) speeding up work and lets
the tool be forced away from the work, instead of into it when it
tries to "grab."

Roy
--- In 7x12minilathe@..., "wdannhardt <wdannhardt@y...>"
<wdannhardt@y...> wrote:

I recently purchased a 7 x 12 mini lathe, and so far it has been
wonderful, I am very satisfied. I purchased a quick change tool
holder from HF, and with a modification to the compound, now have
easy tool height adjustment. The only tool I have problems with is
the cut off tool.

I am using a .062" x .5" HSS tool, cutting brass and Aluminum. I
always seem to get terrible chatter. I made sure the saddle, cross
slide and compound are very tight to the ways, but it still

happens.

Does anyone have any suggestions to make this better? I've not

heard

of anyone else complain about this, so I think it must be something

I

am doing.

Thanks for your help,
WD

There's also a lot to be said for hacksaw parting, followed by a
facing cut :-)

Roy

I have experienced all the problems with parting and, as one member said,even
turned the chuck by hand. With my 7X14 the circuit breaker trips as soon as
the tool hogs. I'm attempting to make a small crankshaft for a model rotary
engine and there is a strong thrust to the piece as it rotates. I have fed as
little as .0001 per turn what really amounts to a scrape. Can anyone explain,
technically, why parting is so difficult?
Max

Sometimes, though, a nice finish cut is needed and the work has no
place to clamp in the chuck for a finish facing cut, or may be marred
by the chuck (although brass shims may be used in this case).

Frequently order of operations may solve the above, but sometimes not.

Craig

--- In 7x12minilathe@..., "roylowenthal
<roylowenthal@y...>" <roylowenthal@y...> wrote:

There's also a lot to be said for hacksaw parting, followed by a
facing cut :-)

Roy
--- In 7x12minilathe@..., Frank Hoose <fhoose@y...>

wrote:

I tend to use the cutoff tool only for stock 1/2" dia.
or less. For bigger stuff, I use the bandsaw.

Frank Hoose


--- "Craig C. Hopewell
<chopewel@r...>"
<chopewel@r...> wrote:

I've had similar problems. First make sure the "T"
type parting tool
is absolutely perpendicular to the work because that
type tool has no
side relief. Try lowering the tool a few
thousandths below center.

A tool ground from square stock (a lot of grinding)
with side reliefs
tends to work better for me, but has some limitation
on cutting depth.

Parting off is, to me, difficult and slowing the
lathe down as is
necessary for such operations reduces motor power.

Craig

--- In 7x12minilathe@..., "bbftx
<bflint@a...>"
<bflint@a...> wrote:

WD
How big a diameter are you trying to part off? A

lot of people

have difficulties with this. It gets dicey on my

7x12 on anything

more than 1-1/8" in diameter. I seem to get the

best results

slowing the rpms way down, as low as I can go with

the speed

control. Also, I make sure I have as little of

the parting tool

as possible hanging out from the tool holder.
B Flint


--- In 7x12minilathe@..., "wdannhardt

<wdannhardt@y...>"

<wdannhardt@y...> wrote:

The only tool I have problems with is
the cut off tool.

I am using a .062" x .5" HSS tool, cutting brass

and Aluminum. I

always seem to get terrible chatter. I made

sure the saddle,
cross

slide and compound are very tight to the ways,

but it still

happens.

Does anyone have any suggestions to make this

better?

I've not heard of anyone else complain about

this, so I think it

must be something I am doing.

WD

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Al,

I like your idea of turning the lathe manually. I have been wanting
to make a crank arrangement for threading manually, but had not
thought of using the same method for parting off.

Craig

--- In 7x12minilathe@..., "fromday2 <aldayis@a...>"
<aldayis@a...> wrote:

I have the HF QCTP and have had the same problem. As others have
stated slow speed is an answer. I have even turned off the lathe

and

turned the chuck by hand while feeding the cross slide, it worked
very well, much better than you might think.

HTH

Al Day


--- In 7x12minilathe@..., "wdannhardt <wdannhardt@y...>"
<wdannhardt@y...> wrote:

I recently purchased a 7 x 12 mini lathe, and so far it has been
wonderful, I am very satisfied. I purchased a quick change tool
holder from HF, and with a modification to the compound, now have
easy tool height adjustment. The only tool I have problems with

is

the cut off tool.

I am using a .062" x .5" HSS tool, cutting brass and Aluminum. I
always seem to get terrible chatter. I made sure the saddle,

cross

slide and compound are very tight to the ways, but it still

happens. WD

--- In 7x12minilathe@..., franksjoy@a... wrote:
Can anyone explain,

technically, why parting is so difficult?
Max

This isn't the technical explanation, but from what I understand
parting off requires slow speed and heavy feed, so what is needed is
high power. If say if a real 1-hp ac constant speed motor were
available, geared down to the necessary low fpm, and an extremely
sharp tool is in use, and everything is rigid, then one could apply
the heavy feed and watch the work's parting line peel right off.

Since we're stuck with the motor arrangement (barring substantial and
expensive mods) only rigidity and tool quality and sharpness can be
controlled and tuned/improved.

Craig

Here's a pretty comprehensive article on parting:


20tooling/Parting%20Off/

Roy

--- In 7x12minilathe@..., franksjoy@a... wrote:

I have experienced all the problems with parting and, as one member

said,even

turned the chuck by hand. With my 7X14 the circuit breaker trips as

soon as

the tool hogs. I'm attempting to make a small crankshaft for a

model rotary

engine and there is a strong thrust to the piece as it rotates. I

have fed as

little as .0001 per turn what really amounts to a scrape. Can

anyone explain,

technically, why parting is so difficult?
Max

WD, a little late in the response, but I'll add my 2 cents worth,
maybe it's already been covered. I had some trouble initially with
parting, but here's what I did. I double checked the height, making
sure of the centerline, then I made sure that the parting tool was as
sharp as possible. I have found that right out of the package, many
of the cut off blades need sharpening. Check for a good relief angle
on the tip, approx 7 to 11 deg angle. Be careful not to overheat the
tip, as it will anneal and soften the end of it. Use the grind -
dip - grind - dip method,and you should be OK. You mention that
you're using the HF QCTP. I have heard of others having parting
problems with the HF cutoff tools. Maybe you can try some other
blades. You may want to make sure also, that you're parting off as
close to the chuck as possible, and that the saddle is locked to the
ways tightly. This will insure that all of the forces are applied to
the parting tool. You may wish to play with the centerline issue
slightly, with some scrap to get the feel of it. Especially on the
softer material (i.e. Aluminium, brass) you shouldn't be having this
problem...

Ed

--- In 7x12minilathe@..., "wdannhardt <wdannhardt@y...>"
<wdannhardt@y...> wrote:

I recently purchased a 7 x 12 mini lathe, and so far it has been
wonderful, I am very satisfied. I purchased a quick change tool
holder from HF, and with a modification to the compound, now have
easy tool height adjustment. The only tool I have problems with is
the cut off tool.

I am using a .062" x .5" HSS tool, cutting brass and Aluminum. I
always seem to get terrible chatter. I made sure the saddle, cross
slide and compound are very tight to the ways, but it still

happens.

Does anyone have any suggestions to make this better? I've not

heard

of anyone else complain about this, so I think it must be something

I

am doing.

Thanks for your help,
WD

All good points, one other thing that I have found is that there is a
tendency to be too timid with the feed.You need too keep up a constant
pressure. On aluminum and brass you should be able to get a constant
curl of metal coming off.

Mark




On Thu, 2003-03-06 at 23:25, Ed Paradis wrote: WD, a little late in the
response, but I'll add my 2 cents worth,
maybe it's already been covered. I had some trouble initially with
parting, but here's what I did. I double checked the height, making
sure of the centerline, then I made sure that the parting tool was as
sharp as possible. I have found that right out of the package, many
of the cut off blades need sharpening. Check for a good relief angle
on the tip, approx 7 to 11 deg angle. Be careful not to overheat the
tip, as it will anneal and soften the end of it. Use the grind -
dip - grind - dip method,and you should be OK. You mention that
you're using the HF QCTP. I have heard of others having parting
problems with the HF cutoff tools. Maybe you can try some other
blades. You may want to make sure also, that you're parting off as
close to the chuck as possible, and that the saddle is locked to the
ways tightly. This will insure that all of the forces are applied to
the parting tool. You may wish to play with the centerline issue
slightly, with some scrap to get the feel of it. Especially on the
softer material (i.e. Aluminium, brass) you shouldn't be having this
problem...

Ed

--- In 7x12minilathe@..., "wdannhardt <wdannhardt@y...>"
<wdannhardt@y...> wrote:

I recently purchased a 7 x 12 mini lathe, and so far it has been
wonderful, I am very satisfied. I purchased a quick change tool
holder from HF, and with a modification to the compound, now have
easy tool height adjustment. The only tool I have problems with is
the cut off tool.

I am using a .062" x .5" HSS tool, cutting brass and Aluminum. I
always seem to get terrible chatter. I made sure the saddle, cross
slide and compound are very tight to the ways, but it still

happens.

Does anyone have any suggestions to make this better? I've not

heard

of anyone else complain about this, so I think it must be something

I

am doing.

Thanks for your help,
WD

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