On Sun, 18 Dec 2011 00:28:52 -0600, Jon Elson
wrote:

wrote:

Last night on my little Rockwell 21-100 mill, I was changing the radius on
the underside of rifle scope base with a boring head.

As I raised the knee, there was cutting close to me, and then as I lowered
the knee there was a new .001" of cutting on the mill side.

Is my vise too heavy? are the knee gibbs loose?
What is going on?
Use a dial indicator to check Y-axis movement when moving the knee.
Yes, it is quite common for the knee slide to cock when the elevating
screw pushes it up or down. Generally, the knee will snug up against
the base when raised, and flop outward towards the operator when
lowered. I never machine anything using the knee. I set the knee to
the right height and use the quill to make up-down movements.
If I need to move the knee to accommodate a different-length tool,
I move it while not cutting, and then always finish with a lifting
movement to keep the knee snug against the base.

Jon

Thats what I do as well. While the knee may be dropped down..I go at
least an inch or 3 below the desired spot..then crank it upwards to
position, then lock it. My Gorton Mastermill has a heavier and beefier
table than a Bridgeport/Clone and even it requires this treatment.

Gunner

One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch