THC pierce height to run height

[David Ballard]

Hello all. New user here and novice CNC plasma user. This is both a Fusion 360 and Mach3 question.

I just acquired a 1 year old plasma table which is running on Mach3. Programming in Fusion 360.
I'm trying to get the THC to work properly. The problem I'm having is THC is either on or off. I want to pierce at Hypertherm's recommend setting (.15") then drop down to cut at the recommended .06". I can make it work by setting the top height at .06" and adding .09" VIA pierce height setting. I think that's a cheat but haven't found any settings in fusion to independently control pierce and run heights. This method works with THC off but with THC on it won't drop down to the run height. I assume there should be a way to turn on THC after it drops to run height. I read this topic viewtopic.php?t=18540 but was hoping someone could shed a little more light. I don't want to get into writing macros or modifying the post processor if it's already built in. This seems like a basic CNC plasma function. Am I missing something in Mach3 or Fusion?

[acourtjester]

You did not state the brand of the THC you are using, and table manufacturer, these help to get a clear answer to your questions. I have not use Fusion 360 so cannot reply about that portion. In SheetCam you can set a pierce height, and a cut height and a pierce delay for the start of a cut operation. And some THC have a delay to turn on the THC after the cut starts, these look at the Arc OK signal. What are you using the turn the THC on/off?

[David Ballard]

The table is manufactured by Singular CNC. THC is a TMC3in1 by CNC4PC. I can figure out the Fusion portion. It does have options for setting the pierce height delay before the cut. I assumed the pierce should initiate followed by a delay, then it would lower to cut height and turn on the THC. As far as I can tell THC is either on or off by toggle button in Mach3, which is how I have been controlling it. I was hoping to find some code to insert to turn THC on after the torch lowers to run height but it seems like that is not possible in Mach3. Please correct me if I'm wrong. A delay in lieu of an on/off is interesting. If I set a .5 second delay before cut for example, a 1.5 second delay before THC takes over might work. Any idea how to do that?

[David Ballard]

acourtjester,
Thanks for the response by the way. You pointed me in the right direction I think. The TMC3in1 has options for m62 / m63 for turning on and off THC, as well as timer option. Now to figure out how to use it.

[acourtjester]

I cannot comment exactly but I think you can use code snippets to do that in SheetCam so they are in the G-code. I have had a little use of them, I'm sure another member can explain what needs to be done.

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