Mike wrote:
Please help need some co-ax instructions...



Guessing that you have one of these knock-offs of the Blake Co-Ax indicator,
and need to know how to use it.

You need a rod that screws into the side of the body to keep it from
rotating.

As your run the spindle at dead slow speeds (ie less than 60 RPM)
a feeler wipes around the ID of the bore you are trying to center over.
If the bore is not very smooth and round, you will find it very difficult
to make the indicator work.

Assuming a round bore, the dial will wobble back and forth. By watching
the dial and the feeler at the same time (making the spindle run even
slower, maybe 25 RPM helps) figure out where the "high spot" is, and
move the table to pull that high spot away from the spindle. When you
get that axis right, the dial will read the same when the feeler is
touching points in line with that axis. Now, adjust the other axis
in the same way. When you get close, the pointer will only wobble a
few thousandths each way. Make very small movements in each axis to
minimize the pointer movement. At some point, you may not be able to
reduce pointer movement below some small amount. This is due to
a bore that is out of round, or possibly a bore that is not parallel
to the spindle rotation. But, the spindle should be as close to
coaxial to the bore as you are going to get.

Jon