My CNC Cincinnati Hawk 150 started to make a big noise/vibration while
Part-off. I make the machine turn counterclockwise with the tool
upside down. Somebody told me the problem could be (this is only a
possibility) the ways are worn because it's not a normal/good practice
to use the CNC that way for Part-off.

What do you think about ?
Has somebody had this problem?
What do you suggest, changing the ways is a very expensive test to do,
I have a small machine shop and I need this machine for my biggest
customer.

Thanks very much

On Thu, 06 Oct 2011 07:21:37 -0700, Rosie wrote:

My CNC Cincinnati Hawk 150 started to make a big noise/vibration while
Part-off. I make the machine turn counterclockwise with the tool upside
down. Somebody told me the problem could be (this is only a possibility)
the ways are worn because it's not a normal/good practice to use the CNC
that way for Part-off.

What do you think about ?
Has somebody had this problem?
What do you suggest, changing the ways is a very expensive test to do, I
have a small machine shop and I need this machine for my biggest
customer.

Thanks very much

AFAIK (and I'm more of a hobbyist than anything else), vibration like
that is either because of lack of rigidity or because your tool profile
is incorrect for the material you're cutting.

The lack of rigidity could be from worn ways, it could be from other
things being loose, or it could be because your tool and/or work holding
is not providing the rigidity needed to keep the chatter from starting.

I couldn't tell you exactly what tool profile is right: my experience
isn't great enough to do anything other than to reduce the rake angle, or
to find a real expert and do just what they say.

My experience is with older and cheaper tools, but with all of them you
tend to give up some rigidity when you run so that the tool pulls up on
the holder -- the ways are designed to resist downward motion, but not
upwards to nearly as great a degree.

So: Why are you turning CCW with the tool upside down? Have you tried to
run things right side up?

Has the machine done this from day 1 for this job, or did it work OK
before and doesn't now? If the latter, then what may have changed?

Have you been using the same tool all along? Could it have gotten dull?
Has it been resharpened? Has it been resharpened _properly_?

Is it chipped?

Have you swapped it out for a different tool? Is the different tool as
rigid?

Are you using the same tool holder? Is the new tool holder as rigid?

I could go on and on -- but I think your best bets are to look at how
everything is held, considering how solidly it is kept in place, and look
at your cutting edge to see if it may be causing the problem.

--
www.wescottdesign.com

On Oct 6, 9:21*am, Rosie wrote:
My CNC Cincinnati Hawk 150 started to make a big noise/vibration while
Part-off. I make the machine turn counterclockwise with the tool
upside down. Somebody told me the problem could be (this is only a
possibility) the ways are worn because it's not a normal/good practice
to use the CNC that way for Part-off.

What do you think about ?
Has somebody had this problem?
What do you suggest, changing the ways is a very expensive test to do,
I have a small machine shop and I need this machine for my biggest
customer.

Thanks very much

My experience if only with manual machines, but normally the forces
push down on the tool post and down on the ways. Most lathes are
designed that way. If I understand what you are doing, the forces
are pulling up on the tool post and trying to pull the tool post up
off the ways. That may be the cause of your problems.

On Thu, 6 Oct 2011 07:21:37 -0700 (PDT), Rosie
wrote:

My CNC Cincinnati Hawk 150 started to make a big noise/vibration while
Part-off. I make the machine turn counterclockwise with the tool
upside down. Somebody told me the problem could be (this is only a
possibility) the ways are worn because it's not a normal/good practice
to use the CNC that way for Part-off.

What do you think about ?
Has somebody had this problem?
What do you suggest, changing the ways is a very expensive test to do,
I have a small machine shop and I need this machine for my biggest
customer.

Thanks very much

The chips clear really nice running CCW upside down IF your machine is
rigid enough.

Mine wasn't, I have to run CW right side up.

I've also seen materials where you have to INCREASE the feed to power
through the chatter point. its a kind of resonance thing.

Just a couple ideas. look at Tim's post too.

Karl

On Thu, 06 Oct 2011 10:01:29 -0700, Denis G. wrote:

On Oct 6, 9:21Â*am, Rosie wrote:
My CNC Cincinnati Hawk 150 started to make a big noise/vibration while
Part-off. I make the machine turn counterclockwise with the tool upside
down. Somebody told me the problem could be (this is only a
possibility) the ways are worn because it's not a normal/good practice
to use the CNC that way for Part-off.

What do you think about ?
Has somebody had this problem?
What do you suggest, changing the ways is a very expensive test to do,
I have a small machine shop and I need this machine for my biggest
customer.

Thanks very much

My experience if only with manual machines, but normally the forces push
down on the tool post and down on the ways. Most lathes are designed
that way. If I understand what you are doing, the forces are pulling
up on the tool post and trying to pull the tool post up off the ways.
That may be the cause of your problems.

The only time that I've heard of using the lathe in reverse rotation is
for threading, so the tool will be moving away from the work piece (so
you don't have to stop the lathe just in time to prevent breaking
anything). And wherever it was that I read about that, the author was
also advising that you use a left-hand tool on the back side of the work,
so that the tool would still meet the downward-traveling face of the work.

--
www.wescottdesign.com

On Oct 6, 12:59*pm, Tim Wescott wrote:
On Thu, 06 Oct 2011 10:01:29 -0700, Denis G. wrote:
On Oct 6, 9:21*am, Rosie wrote:
My CNC Cincinnati Hawk 150 started to make a big noise/vibration while
Part-off. I make the machine turn counterclockwise with the tool upside
down. Somebody told me the problem could be (this is only a
possibility) the ways are worn because it's not a normal/good practice
to use the CNC that way for Part-off.

What do you think about ?
Has somebody had this problem?
What do you suggest, changing the ways is a very expensive test to do,
I have a small machine shop and I need this machine for my biggest
customer.

Thanks very much

My experience if only with manual machines, but normally the forces push
down on the tool post and down on the ways. *Most lathes are designed
that way. * If I understand what you are doing, the forces are pulling
up on the tool post and trying to pull the tool post up off the ways.
That may be the cause of your problems.

The only time that I've heard of using the lathe in reverse rotation is
for threading, so the tool will be moving away from the work piece (so
you don't have to stop the lathe just in time to prevent breaking
anything). *And wherever it was that I read about that, the author was
also advising that you use a left-hand tool on the back side of the work,
so that the tool would still meet the downward-traveling face of the work..

--www.wescottdesign.com- Hide quoted text -

- Show quoted text -

That makes sense. The forces would still be be pressing down on the
carriage and ways.

"Rosie" wrote in message
...
My CNC Cincinnati Hawk 150 started to make a big noise/vibration while
Part-off. I make the machine turn counterclockwise with the tool
upside down. Somebody told me the problem could be (this is only a
possibility) the ways are worn because it's not a normal/good practice
to use the CNC that way for Part-off.

What do you think about ?
Has somebody had this problem?
What do you suggest, changing the ways is a very expensive test to do,
I have a small machine shop and I need this machine for my biggest
customer.

Thanks very much

On my 10" manual lathe the quickest cure for vibration when parting is
reducing spindle speed.

jsw

On Thu, 06 Oct 2011 12:52:28 -0500, Karl Townsend wrote:

On Thu, 6 Oct 2011 07:21:37 -0700 (PDT), Rosie
wrote:

My CNC Cincinnati Hawk 150 started to make a big noise/vibration while
Part-off. I make the machine turn counterclockwise with the tool upside
down. Somebody told me the problem could be (this is only a possibility)
the ways are worn because it's not a normal/good practice to use the CNC
that way for Part-off.

What do you think about ?
Has somebody had this problem?
What do you suggest, changing the ways is a very expensive test to do, I
have a small machine shop and I need this machine for my biggest
customer.

Thanks very much

The chips clear really nice running CCW upside down IF your machine is
rigid enough.

Mine wasn't, I have to run CW right side up.

I've also seen materials where you have to INCREASE the feed to power
through the chatter point. its a kind of resonance thing.

Just a couple ideas. look at Tim's post too.

On my lathe when I increase the feed to power through the chatter point,
things flex enough that my parting-off tool binds and breaks.

Granted, at that point things aren't chattering. But it's not an
improvement :-).

--
www.wescottdesign.com

"Rosie" wrote in message
...
My CNC Cincinnati Hawk 150 started to make a big noise/vibration while
Part-off. I make the machine turn counterclockwise with the tool
upside down. Somebody told me the problem could be (this is only a
possibility) the ways are worn because it's not a normal/good practice
to use the CNC that way for Part-off.

What do you think about ?
Has somebody had this problem?
What do you suggest, changing the ways is a very expensive test to do,
I have a small machine shop and I need this machine for my biggest
customer.

Thanks very much

Check the gibs

"Tim Wescott" wrote in message
...
On Thu, 06 Oct 2011 10:01:29 -0700, Denis G. wrote:

On Oct 6, 9:21 am, Rosie wrote:
My CNC Cincinnati Hawk 150 started to make a big noise/vibration while
Part-off. I make the machine turn counterclockwise with the tool upside
down. Somebody told me the problem could be (this is only a
possibility) the ways are worn because it's not a normal/good practice
to use the CNC that way for Part-off.

What do you think about ?
Has somebody had this problem?
What do you suggest, changing the ways is a very expensive test to do,
I have a small machine shop and I need this machine for my biggest
customer.

Thanks very much

My experience if only with manual machines, but normally the forces push
down on the tool post and down on the ways. Most lathes are designed
that way. If I understand what you are doing, the forces are pulling
up on the tool post and trying to pull the tool post up off the ways.
That may be the cause of your problems.

The only time that I've heard of using the lathe in reverse rotation is
for threading, so the tool will be moving away from the work piece (so
you don't have to stop the lathe just in time to prevent breaking
anything). And wherever it was that I read about that, the author was
also advising that you use a left-hand tool on the back side of the work,
so that the tool would still meet the downward-traveling face of the work.

--
www.wescottdesign.com


That is an old machinist's trick when they are using a machine at its upper
limit.
Most of the machines with Tee slots in the cross slide have, as an
accessory, a rear tool holder for parting off. The force is transmitted more
directly to the ways without going through the compound so there is less
opportunity for " looseness"
I don't know anthing about CNC usage but I would expect the same rules to
apply

In article
,
Rosie wrote:

My CNC Cincinnati Hawk 150 started to make a big noise/vibration while
Part-off. I make the machine turn counterclockwise with the tool
upside down. Somebody told me the problem could be (this is only a
possibility) the ways are worn because it's not a normal/good practice
to use the CNC that way for Part-off.

What do you think about ?
Has somebody had this problem?
What do you suggest, changing the ways is a very expensive test to do,
I have a small machine shop and I need this machine for my biggest
customer.

How much does the Hawk 150 weigh?

What material are you cutting, how big is it, and how fast are you
turning? And what kind of cutoff tool are you using?

I do cutoff with Clausing 5914 late in reverse with upsidedown SGIH
blades, and it works just fine. Running in reverse prevents
self-feeding of the parting tool into the cut, and keeps the chips from
staying in the cut. But it needs a real coolant flood to get fluid to
the bottom of the cut.

But before I could part off without bone-jarring chatter, I had to
tighten just about everything. It was quite the saga.

Joe Gwinn

"Tim Wescott" wrote in message
...
On Thu, 06 Oct 2011 10:01:29 -0700, Denis G. wrote:

On Oct 6, 9:21 am, Rosie wrote:
My CNC Cincinnati Hawk 150 started to make a big noise/vibration while
Part-off. I make the machine turn counterclockwise with the tool upside
down. Somebody told me the problem could be (this is only a
possibility) the ways are worn because it's not a normal/good practice
to use the CNC that way for Part-off.

What do you think about ?
Has somebody had this problem?
What do you suggest, changing the ways is a very expensive test to do,
I have a small machine shop and I need this machine for my biggest
customer.

Thanks very much

My experience if only with manual machines, but normally the forces push
down on the tool post and down on the ways. Most lathes are designed
that way. If I understand what you are doing, the forces are pulling
up on the tool post and trying to pull the tool post up off the ways.
That may be the cause of your problems.

The only time that I've heard of using the lathe in reverse rotation is
for threading, so the tool will be moving away from the work piece (so
you don't have to stop the lathe just in time to prevent breaking
anything). And wherever it was that I read about that, the author was
also advising that you use a left-hand tool on the back side of the work,
so that the tool would still meet the downward-traveling face of the work.



I sometimes program the cnc swiss to continue in reverse after tapping,
finally going into forward again when the chuck is opened after part-off
while fresh stock is being fed out for the next piece...shaves off a bit of
cycle time...

First, I hope you mean ccw from the outboard end of the spindle. If
otherwise, you are going the wrong way.
Do you use a lantern tool post? I gave up on mine many years ago. Not
rigid enough. Do you know that the chips are wider than the cut if they
heat up at all? That's why one uses a lot of coolant. Is your tool set
just on or just below the center line so if it grabs, it pulls away from the
cut?
Do you tighten all gibs? Have you tried different speeds to see if the
vibration rate changes or disappears? How far is the work sticking out of
the lathe chuck? I always try to have the cut real close to the chuck.
I have a 10 inch manual Atlas lathe, so it is pretty light, but I cut-off
successfully on a regular basis, but not usually on a production basis.

Pete Stanaitis
---------------