THC Sheet Cam and Action Points

I’ve been doing some ‘self training’ while I’m waiting on Box 1 (batch 2) and have been designing some ‘first cuts’ to play with once I get setup and running. Attached is an example of some playing around I’ve been doing in Sheetcam with Action Points. Action Points allow you to make some changes to the cut path dynamically - feed rate, etc…

I’ve got the path highlighted to slow down to 25% of the cut rate and disable THC, enabling it again when out of the area.

My question is: with Firecontrol and THC, is this necessary or will it cause problems with the auto THC system? I would run some experiments, but I’m not setup yet, and I’m more looking for a recommendation if doing things like this is wise with Firecontrol.

Also, if doing this type of thing is ok and doesn’t cause other issues, what are the correct G codes to turn THC On and Off. I’m using S21 and S20. I’m not sure if those are correct - I picked them up somewhere, but it may have been a tutorial not related to Crossfire Pro.

Edit: I found this post : THC ON/OFF Gcode
It says H0 off and H1 on. For this post assume S21 = H0 and S20 = H1.

G-code Output (1.5 Firecontrol Sheetcam processor)

Definition in Sheetcam

I need to check the “Action Points” feature out. Out of curiosity - why would you turn the THC off?

So from what I understand, you’d do this to stop the torch from diving as the voltages will change when the speed drops and the THC will try and compensate. This is sort of why I’m asking, because I know the CF Pro THC has some “smart features” and not sure if doing this would negate the benefits.

I’m trying to figure out if doing things like this manually in Sheetcam are counterproductive to the logic that the CF Pro’s THC module has. I’m thinking that some of the features like this in sheetcam are for other systems that may not have things like smart THC. But then again, if I know this cut profile is going to need some ‘assistance’ for good cut quality, sharp corners, etc…does it make sense manually do things like this or just let Firecontrol have at it.

Perhaps it’s smarter to just lower the speed for the sharp turn using an action point, and leave THC setting on and let it figure out what to do…?

It would be easy enough to test, but as I mentioned, I’m still waiting on table. Just looking for some tips, ideas.

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M3 on, M5 off. H0 THC off H1 THC on.
See TORCH SPEED CUTOFF SETTING section. Basically it turns off the THC when speed is commanded lower. I am not sure if you will still want the fine tuning, I would assume so, as the THC helps with uneven surfaces but it won’t know to cut a small radius at a slower speed.


I think you just connected the dots for me. Use action points to slow down, but no need to manually turn off the THC, as it will sense the drop and disable automatically based on your Cutoff setting. That makes sense - Thanks! Also RTFM helps lol!

Yes I think that is the way to go, at least to start.


I think I saw that FireControl would slow down in corners too. But I can’t find the post or see it the doc. @langmuir-daniel would know.

Yeah I think I read that somewhere as well. Would like to see a reference on how that works. Its probably in the manual somewhere…

If that’s the case, then there’s really no need to do this stuff with Action Points unless you just really want to control every detail and override the work that LS has done to make this stuff work. I’ll guess time will tell as we use these tables more…

For future reference - some other related threads: