On Tue, 07 Jun 2005 19:44:02 -0700, Dennis Shinn
wrote:

Totally new to metal turning on an engine lathe. Bought an inexpensive
(read cheap Chinese) Grizzly machine which is about all I really need
for my hobby type projects but - seems to me I'm getting way more
chatter trying to turn stuff than even this machine should produce.

I'm trying to turn a grooved disk, 3" in diameter. I faced off a piece
of stock (in a three jaw) and turned about 2" reasonably true. Then
took an old carbide cutter my brother gave me, looked something like a
thread cutting tool, and ground the end to about a 3/8" radius. On a
green wheel, of course.

If I 'touch up' the tool on the ginder, go back to the lathe, I'll get
a really nice curly chip off the stock at first then the tool will
start to chatter and I'll get a whole mess of little semi-circular
shavings, if you will.

I've checked and rechecked the tool for center and it's as close as I
can get. This chatter occurs with or without lube. (Using Lennox
ProLube applied manually).

Am I just asking more of this lathe than it can produce? It's the
12x36 Grizzly gear head model.


Probably too big of a radius on the tool. It should be "pointed" but
with a tiny bit of radius, not a sharp point. You've got too much
contact between the part and the tool. Also try increasing the chip
load on the tool by slowing the relationship of the rpm to the
feedrate. In other words feed faster at the same rpm or use slower rpm
at the same feedrate.
Randy