Background

The ohmic probing system on the 1300PL relies on a calibrated resistance value between the torch cap and the workpiece. If you do not calibrate your ohmic probe, you may find that it is triggered by water on the work piece or inside the torch cap.

Tools

• Phillip’s head screwdriver

Step 1

Open the electrical cabinet and identify the Tormach TCHT Board (PN 39096)

Depending on which revision of the board you have, the sensitivity potentiometer will look different.

Step 2

Select a piece of sheet metal to use as a test workpiece. Connect it to the ground clamp.

Step 3

Jog the torch downwards in Z until the torch cap contacts the workpiece. Watch the LED D8 on the bottom left of the board. If the LED lights up when the workpiece contacts the torch cap, the THCT board is measuring contact between the cap and ground as intended.

Step 4

If the LED did not light up, identify adjustment screw RV1 on the TCHT board (indicated in the image above). Increase the sensitivity by rotating the screw clockwise, 1/16th turn at a time until the workpiece is detected.

Step 5

Splash a small puddle of water onto your workpiece. Jog the torch cap down until it is contacting the water but not the workpiece itself. If the LED is on, your TCHT sensitivity is too high. Decrease the sensitivity 1/16th of a turn at a time until the LED goes out.