Update for anyone interested.
- None of my coding attempts worked to code the actual input signal. Either I am just that bad at code, it was in the wrong file / position, or it just plain didn't work.
- Bob at pmdx's solution with the spindle works very well. However, I had to enable reverse in the spindle setup screen in Mach, and I had to make sure Const. Surface was selected in the General tab, as opposed to Const. RPM. I have no idea why, but doing those things actually made it work well. Thanks very much Bob. Huge weight lifted off my brain.
Just to elaborate further for future reference. I have to set the torch to fire during the height sensing process due to a very slight delay from when the THC commands motion versus when the signal is sent for motion. This I believe is a THC/plasma machine issue that I think I can solve. If not, then I can add a half second dwell after M03 to fix it so I can save consumables a bit.
Also, very occasionally, Mach will get hung up on the M05 command. Its inconsistent, so I think its just the demo version of Mach messing with functions. Luckily, I can finally resolve that issue tomorrow.
Chaotic - I'll check out that information next to see what its all about, thanks for the info. I did try using a signal script earlier, but it was either in the wrong place or my code is just bad.