Torch height is off.. how to fix it?

[Pat4rd]

I've really been burning through some hypertherm consumables, went to check my torch height and it appears to be pretty high. I did this by turning the torch off, running a simple line file and sticking a .06" shim under it. There was a big gap between the torch and the shim. I went back to sheet cam, plugged in .008 and now I can fit my shim under it with no gap. What's the best way to correct this? I've got a proma thc 150, Mach 3, 45xp with a machine torch. I would rather fix this the right way instead of putting .008 in the computer.. Thanks for any help!

[acourtjester]

Cleaning the nozzle first, are you using a floating head switch or a ohmic sensor to set Z zero for your pierce height?

[Simko]

Have you calibrated your z-axis steps? Pick a stationary point on the z-axis and a moveable point and measure between with calipers. Manually move the z-axis a known amount and re measure to verify it moved the distance you told it to move. If it is off, use the MACH procedure for calibrating steps per unit measurement.

If your steps are correct, then it has to be your switch offset that is wrong.

[tcaudle]

The THC has no idea where the Z DRO is nor does it care. It simply moves to make the arc volts correct. Assuming the THC is working it moves the Z to whatever height it takes to maintain the Arc Volts during the cut. In the conventional parallel port setup MACH takes the UP and DOWN is as a Z jog and simple moves the motor the distance to hold the volts and tracks how far that is. In short Height = Arc volts (all other things set according to the chart). The touch off needs to be accurate to get a correct pierce. Too low and you get blow back. Too high and you get upper slag or a bad pierce.

The PROMO is a very basic UP- Down sending unit and there is no communication between the THC and MACH or vice versa..

You Z can be out of calibration and the DRO will read different from the actual height but the actual gap is wat counts

[Pat4rd]

Thank you all! I will check that.. I'm just learning all of this new stuff.

[bloftin]

This post was very beneficial to me thanks all that have contributed to it