Powermax30XP wiring interface for CNC

[yaxy]

wires:
black - work piece clamp - labeled WORK LEAD (BLK)
white - electrode
red - pilot arc to nozzle
orange - start switch 1 - labeled START
violet - start switch 2 - labeled "I"
blue - ? - labeled TORCH on circuit board, CAP SW NC on schematic

connections:
work lead (+) to electrode (-) - arc voltage for torch height controller e.g. Proma Compact THC 150
parallel start switch 1 and 2 to normally open relay contacts

questions:
What is the purpose of the blue (TORCH/CAP SW NC) lead?
Is there any way to pick off the OVERHEAT SHUTDOWN signal (other than watching arc voltage drop to 0)?
It is important to know when arc is transferred from pilot (firing) to work piece (cutting) and vice versa when e.g. cutting expanded metal or passing over a hole or wide kerf?

Caveats acknowledged modding Powermax30XP for CNC:
* no convenient CPC connector for start switch and 50:1 divided arc voltage
* warranty void
* dangerous voltages
* only 35% duty cycle
* no machine torch

Thanks!

[jimcolt]

As a Hypertherm associate of 39 plus years (and I like my job!) I cannot recommend any modifications to the wiring in our units. I would recommend that for CNC use you limit the maximum cutting thickness to about 3/16" (4.5 mm)....this will increase the duty cycle and will allow for good consumable life. Pierce at twice the cut height, and with an adequate pierce delay time so that x or y motion only begins after the arc has fully penetrated the material. Jim Colt Hypertherm

wires:
black - work piece clamp - labeled WORK LEAD (BLK)
white - electrode
red - pilot arc to nozzle
orange - start switch 1 - labeled START
violet - start switch 2 - labeled "I"
blue - ? - labeled TORCH on circuit board, CAP SW NC on schematic

connections:
work lead (+) to electrode (-) - arc voltage for torch height controller e.g. Proma Compact THC 150
parallel start switch 1 and 2 to normally open relay contacts

questions:
What is the purpose of the blue (TORCH/CAP SW NC) lead? This is a safety feature found on all Hypertherm torches that shuts off the DC power supply when the retaing cap is unscrewed....voltage in the torch can be as much as 300 VDC.
Is there any way to pick off the OVERHEAT SHUTDOWN signal (other than watching arc voltage drop to 0)?I cannot recommend doing this, it is also not a good idea to repeatedly run a power supply to its duty cycle trip temperature.
It is important to know when arc is transferred from pilot (firing) to work piece (cutting) and vice versa when e.g. cutting expanded metal or passing over a hole or wide kerf?Arc transfer output is available on Hypertherm systems that are recommended for CNC use, this signal is used to activate the height control as well as the motion on most cnc machines.

Caveats acknowledged modding Powermax30XP for CNC:
* no convenient CPC connector for start switch and 50:1 divided arc voltage
* warranty void
* dangerous voltages
* only 35% duty cycle
* no machine torch

Thanks!

[yaxy]

Recommend against wiring modifications: Of course. This is only a theoretical discussion.
Limited thickness to 3/16": Yes, intent is to only cut thin stock until a 45 or higher is needed and in the budget.
Pierce height: Good point. Though the 30XP has no problem piercing while hand held with the drag shield contacting the work piece, might as well raise the torch during CNC piercing to prolong the life of the nozzle and shield.
Pierce delay: Too bad there isn't an automated way to know when pierce has occurred. Camera looking for sparks under the work piece?
TORCH/CAP SW = safety: Good feature!
OVERHEAT SHUTDOWN signal: The thinking here was to use it as a sort of "limit switch" to stop everything in case duty cycle is accidentally exceeded. Obviously the operator will see when this occurs and will put a stop to things. Hopefully there is a G-code command to "do nothing for X seconds" after Y seconds of cutting to allow the 30XP to cool down.
Arc transfer signal: In lieu of this signal on non-CNC plasmas, I guess measuring current through work piece cable would indicate when arc has transferred and cutting has started.

Thanks for the info and suggestions.