Need Help!- THC300 set volts adjustment problem

[jeremyrockjock]

I have been running my table a while with mach3 and thc300 but the THC has never been working that great. It will keep the tip from bumping into the metal but it will not move down as the gap widens. I started looking back through the setup for the THC and it says to set voltage a 87 volts. I cannot get my tip height knobs to change any value on the DRO. It remain 000 until the torch is on. What am I doing wrong?

[Torchhead]

Originally Posted by jeremyrockjock I have been running my table a while with mach3 and thc300 but the THC has never been working that great. It will keep the tip from bumping into the metal but it will not move down as the gap widens. I started looking back through the setup for the THC and it says to set voltage a 87 volts. I cannot get my tip height knobs to change any value on the DRO. It remain 000 until the torch is on. What am I doing wrong?

The THC300 does not have presets. The readout only shows the actual cutting voltage...period. You cannot dial in a preset voltage. You have to start the cut and adjust the course and fine knobs as ti cuts until the arc gap is correct. It is basically a "knob-chaser" approach. Once you have it set it usually needs only minor tweaking unless you change to Fine Cut or lower the cut current drastically. The THC300 is pretty old technology by today's standards. It is a simple analog circuit with no presets, no anti-dive, no parameter adjustments.

TOM caudle
www.CandCNC.com

[jeremyrockjock]

Any thoughts on why my torch will not adjust down when the material drops below the set tip height?

[jeremyrockjock]

I still cannot get this thc300 to work right. I have read the instructions til i am blue in the face. Here is the intial testing in the guide.

Please refer to the included screen shots during this test, as well as the actual Mach3 screens.
With Mach3 running click on the Reset (solid Green) button on the lower left corner of the main screen. The Ready LED will light. And the set volts will be on the meter.Adjust the set voltage to about 87volts.
Click on the “Torch ON” button the Mach3 screen. You will hear a relay click on the sensor board and see the Torch On LED light up on the Front Panel.
Center the coarse and fine controls (pointers UP).
The meter will drop to zero volts. This would normally read the actual tip volts at this time.
Take a short clip lead and clip TP8 and TP5 on the logic PCB together. You will see the voltage read about 87 volts on the meter. You will be able to adjust the coarse control until both LEDs are off. It is very sensitive; something to remember when you are setting up a job. The Fine control will remain centered.


What meter are they talking about and where is this "ready" LED?