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