Re: Capacitive sensor for gas/plasma cnc ...
Ohmic sensing is simply a method for sensing the surface of the material when probing where the torch shield and the material form a switch that is turned on on contact. There are other methods like a floating probe sensor and even stall sensing on the Z axis motor. Torch height control (THC) systems rely on the fact that there is a linear (eg. straight line) relationship between the arc voltage and torch height. So that means if you know the torch voltage, you can calculate the torch height very accurately. This is not possible with an oxy torch so the capacitive sensor senses the proximity of the ring to the surface of the material. I've no experience with it but I suspect its not as accurate as a THC and requires additional hardware which is not required with a THC system.
Rod Webster
www.vehiclemods.net.au