Re: [CAD_CAM_EDM_DRO] Re: Mill recommendations needed for new CNC Project

mayfieldtm wrote:

>
> If I was to convert a Knee Mill. I'm thinking of controlling the Knee
> movement and leaving the spindle alone. On manual machines, I do most
> of any drilling operations using the Knee, except when I need to to a
> lot of pecking.

The Bridgeport quill is quite robust, and coaxial in the sense
that the entire quill is surrounded by the main head casting.
So, wear will be roughly symmetrical. You have to REALLY abuse
a Bridgeport to suffer a loose quill fit.

The weight on the knee ways is totally asymmetrical, wearing the
dovetail so there will be a loose spot. Even the clones with
box ways still have some measure of this problem. So, unless
you are retrofitting a new or lightly-used machine, watch out
for worn knee ways. If you CNC the knee as your Z axis, then
you will never be able to clamp the knee ways to tighten up that
axis. On my old Bridgeport, for instance, the table moves about
.001" in the Y-axis direction when you reverse directions of the
knee. Not a problem as my knee is manual, and I always raise it
as the last movement.

Jon