THC300 problems

[signslingerz]

Hi Guys, I'm running sheetcam thc300 post processor and the latest version of mach3. The plasma table is operating as it should in all aspects except the thc300. The problem is that when I cut, the z axis references to 0 lifts to the
correct pierce height pierces then moves to cut height which is .10 and starts
to cut at cut height which is .05 after about 2-3in the z axis will adjust to
approx .30-.50 and continue cutting. Everything else is working like it should.
The thc seems to be working cause the led's are lighting up for up and down for down (onscreen), and the z axis is moving to adjust. It's just to high. The dro is reading between 70-130 on the thc. fine cut is switched off, the thc max is set to +3.5in and MIN is set to -1.0 . the switch ref in sheetcam is set to .05 If i turn on the fine cut switch the z axis will bury down to 0 and cut at that height until I stop it to avoid problems. What can I check or what should I do cause i'm at my wits end with this one. Any advice would certainly be appreciated !!THANK YOU!! in advance

[Torchhead]

Hi Guys, I'm running sheetcam thc300 post processor and the latest version of mach3. The plasma table is operating as it should in all aspects except the thc300. The problem is that when I cut, the z axis references to 0 lifts to the
correct pierce height pierces then moves to cut height which is .10 and starts
to cut at cut height which is .05 after about 2-3in the z axis will adjust to
approx .30-.50 and continue cutting. Everything else is working like it should.
The thc seems to be working cause the led's are lighting up for up and down for down (onscreen), and the z axis is moving to adjust. It's just to high. The dro is reading between 70-130 on the thc. fine cut is switched off, the thc max is set to +3.5in and MIN is set to -1.0 . the switch ref in sheetcam is set to .05 If i turn on the fine cut switch the z axis will bury down to 0 and cut at that height until I stop it to avoid problems. What can I check or what should I do cause i'm at my wits end with this one. Any advice would certainly be appreciated !!THANK YOU!! in advance

The important thing is the voltage display. The THC 300 is a simple analog comparator with a "window" setting (roughly 1V) The Fine and Course knobs set the "Preset" point and the circuit reads the actual voltage and uses the preset to decide if it needs to go UP or DOWN. If the unit gets a DOWN and fails to go down then it will track too high.

On setting that can cause that is the THC Corrections in MACH. There is a MIN and MAX. It sets how far in ABSOLUTE distance the Z can move during THC control. If you have the Min set to a positive number it will adjust up just fine but never let it come back down. Set the MIN value to -.250 or to turn it off set it to -1.00. It's there to keep the torch from running over a void and trying to lower voltage by lower the head down too far.

So as it climbs out of the cut what happens to:

1. The voltage display (should be going up)
2. The UP down LEDS (Down should be one if the voltage is going up (higher)
3. The Z motion based on the UP and DOWN commands

Anytime the UP is on the Z should be moving up. Any time the DOWN is on the Z should be moving DOWN. The Z DRO should be tracking.


TOM Caudle
www.CandCNC.com