I am using Mach3 and I have been zeroing the Z axis using the eyeball or paper routine. In the past I was using a piece of stainless steel shim stock and a continuity checker. Its been mis filed in the mess I call my shop. So I have another continuity checker and some shim stock again to try.
In the mean time I found one of the LED zero indicators on Amazon and have one ordered. Magnetic which will work great on my wood projects but I have plan to clip a wire to the spindle. Just wondering if the folks on here are using a auto zero macro in your software or how?