"Dom" wrote in message
oups.com...
This is driving me crazy. I've tried everything I can think of.

-Centre height OK.
-Blade not overextended.
-Insert OK
-Coolant on
-Reduced speed, increased feed
-Adjusted backlash on cross slide to minimum
-Saddle clamped
-Happens with different materials, and diameters

But I can't eliminate the vibration. It is really heavy, and is
causing clamping screws and the like to loosen.

It's making me feel like a complete idiot. I should be able to solve
this problem, but what's causing it?

Any suggestions, or should I just go and slash my wrists now?! g

Cheers, Dom.


Been there, done that...

This may not be correct, but I found that grinding the cutoff tool
to put a chip-breaker in the top surface solves the problem. It
seems to me that expecting the chip to make an abrupt right angle
turn the instant it gets cut off is asking a bit much... So, I grind
the tool such that the top of the cutting edge, instead of being
perpendicular to the tangent of the surface to be cut, it is at more
like 45 degrees or so.

Oh, and sometimes when parting a large piece of work, it helps
to make two cuts. Go in a ways, back out, move the lathe carriage
20 thou or so, and go back in. Cutting in "steps" like this keeps
the tool from binding up in the slot it just cut and also it is more
tolerant of the tool being aligned slightly off perpendicular to the
axis of the work.

Jerry