THC Parameters

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28 Dec 2023 17:21 #289268 by LucasWorx
THC Parameters was created by LucasWorx
Hey Guys,

   Is there a manual somewhere that defines the THC parameters for QTPlasmac? Just something that specifies what parameter does what. I'm having some serrated looking cuts on thinner metals (14-18 ga) due to what I believe is the torch moving up and down to quick. I have a 7i96S with THCAD-10 using 45XP and my settings are pretty much the same as I've seen others post:

50 Sample counts
1.00V Sample Threshold
1.00V Threshold
10 Speed (PID-P)
90% VAD Threshold
500V/Sec Void slope
0 PID-I
0 PID-D

I tried going down to 65% VAD threshold as suggested in another post but did not see a change. Also, I've been pausing the cut, making the change, saving, and resuming the cut to look for differences. I'm assuming the save parameters button takes place without having to restart QTPlasmaC.
 

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28 Dec 2023 17:55 #289270 by snowgoer540
Replied by snowgoer540 on topic THC Parameters
linuxcnc.org/docs/devel/html/plasma/qtpl...lasma:parameters-tab

Scroll down to "Configuration -THC"

Probably not exactly what you're looking for.  I can get my parameters from my machine (65XP), but I think they are the default settings.  A lot of the tuning parameters depend on the speed of the Z axis, etc.  

But as another place to start, I would verify that the voltage readings are not noisy/don't have interference issues, etc.  When I was doing mine, I opened up the halscope and continually plotted the output from the THCAD.  I was able to see that having the ground connected to the shield was causing all sorts of noise, which calmed down then I removed the shield connection.  I also then hooked up a DC power supply to it and verified that it showed the correct voltage value.  I cant remember I either used a 9v or a 24v power supply I had laying around etc.  Lastly, I did some looking at the voltage under a long torch pulse, etc.  Erroneous noise in this system can cause you a lot of grief.  The GUI updates arent fast enough to really show everything, so it's best to use halscope to plot the voltage under the aforementioned conditions, as well as cut conditions  on thicker material (with the THC disabled), etc.  

Hopefully that helps give you some places to look before you start turning the knobs :)

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