"...I haven't tested the repeatability on them, but from all i've read, they are very accurate. (.01mm), I'll get back to you tomorrow on that one."
Thanks for the suggestion. It is the "repeatability" in particular which is the issue. I spent a day, trying to calibrate my machine's Z axis using a touch plate on the stock, and a fixed plate mounted on table. The results kept varying as much as 0.050" I finally concluded that this was the amount of "play" in the microswitch, when homing the machine. And since all movements in Mach 3 are referenced from the (make, or break contact) of the limit switch, then the microswitch must be the variable culprit. I am currently using a ball screw on the Z axis, so I don't think that it's an issue with the mechanical aspects, other than the limit switch movements. What brought it to my attention, was upon re-homing my machine, I noticed that the Machine Coordinate display on the Z axis would always read something other than zero (resetting to zero, of course upon striking the limit switch).