I did it on my sherline mill and my router. I used a maxnc touch probe, later I used a simple proximity switch (about 1/10 the cost). These where hooked up to a pin on the parallel port on the controlling machine running TurboCNC. Two special g codes where used on turbocnc for movement, one moves until the touch strikes the workpiece and the other probes a two dimensional area backing off after a contact. All points are recorded automatically and the precision is the same as your stepper control. This may be good or bad. You can get Turbocnc for free to try it and almost any sensitive switch can be used to test the system. I suggest you use the smallest machine available to do the readings as the scale of error is important. On the sherline with the proximity switch I get repeatability of ~.001. |