Hi,
if the material allows the use of an ohmic probe touching off is so simple and accurate. Probing has become for most operators the technique of
choice.
If the material is non conductive a small piece of metal of known thickness and connected via a flexible wire to your controller is laid on the work surface.
Either an on-screen probe button or and MDI G31 probe code is issued and the spindle (not running) lowers until contact is made with the metal.
The Z co-ord is set to the gauge thickness of the metal.
If the work piece is conductive but is isolated from the frame of the machine a wire from the conductive surface is connected to your controller.
Probe contact occurs when the tip of the tool which is clamped with metal collets in the spindle which is in turn earthed to the frame of the machine.
This is a common procedure for me when I make circuit boards. One probe wire is clipped to the top copper surface of the circuit board blank
and the other wire is clipped to the spindle shaft with an alligator clip. The probe input of my controller detects the short that occurs when the tip
of the tool touches the circuit board blank. In this case the gauge thickness is zero, ie the Z work co-ord is set to zero, easy.
Craig