On Dec 19, 9:23*am, " wrote:
...
As far as the round column..........Almost all of the time it is no
problem. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * Dan

I just remembered that when I had to move the head I centered a small
hole under it first and then afterwards located the head on that hole
with a center finder. The center finder shank fits in a collet when
the head is down and a drill chuck when it's up, effectively adding
the height of the chuck to the accurate Z axis range of the machine.

jsw