Trying to sort out the THC with PlasmaC

Ok I have ditched the scratch start plasma and purchased a pilot arc one with machine torch but no cnc socket on it.

I have wired the Mesa THC-10 inputs via 1 meg R. in each leg. I can now fire the torch via the onscreen pulse button But could not get the arc volts to show.
I then read the manual 16.2 told me to put setp ~~~~~~~~encoder.00.scale -1 and~~~~~~encoder.00.counter-mode 1 In the ini file

I think that was a misprint in the original manual. It has changed to section 18 with the same lines but says put it in the hal file.I have connected a 9V battery (actual measure 9.68V) to the input terminals on the THC the arc voltage on screen shows random 56-112V

Please see Hal Show and my config files. ~~~encoder.00.input-a flashes on & off with the battery connected
Should the ~~~encoder.00.velocity be showing -ve

phillc54 wrote:

Have you set Voltage Scale and Voltage Offset in the Config Panel?

Edit: My 7i96 has the encoder jumpers set as:
W2 = right
W3 = left
W4 = right

Edit2: I just noticed that the User Guide on the LinuxCNC site is a bit different to the one on mine, I don't know why yet...
home.iprimus.com.au/phillcarter/plasma/plasmac-user-guide.html
Edit3: fixed...

Many Thanks Phil.
W3 was incorrect. I have changed the scale to .01 and the offset high = 230 Low = 10 (for testing)

With the above (I have the torch on a static mount off the machine about 2mm from a metal plate) It will now simulate cutting the wrench out with the torch firing and being kept on for the duration of the cut.

Not quite sure how to calibrate the above the sticker on the back of the THC states 0V = 117.6 khz 10v = 924.3 khz
the 9V battery measures 9.68v

phillc54 wrote:

I think you have 2 X 1M resistors so:
for scale it would be 21/((924300−117600)/32/10) = 0.00833023
for offset it would be 117600/32 = 3675

linuxcnc.org/docs/devel/html/plasma/plas...ng_the_divider_ratio
linuxcnc.org/docs/devel/html/plasma/plas...#_calibration_values

Thanks Phil. That did it, now the display is steady and at zero before the run command is started.

Sorry more questions on setup . Phill
I have the machine now cutting. I have cut out the test Spanner at 5mm with quite a lot of dross

The machine probes OK and fires OK I had the cut height set to 1.25mm but pretty sure it is more like 5mm

Q1. When doing a probe test. The z does probes down at G0 speed to the probe height 30mm then probes down at probe speed OK
then it moves up a few mm then after a delay it move further up about 25mm.

Does the first move up signify cut height ?

When run with the torch enable button, disabled. I can see then that it is trying to cut too high at 5mm


What would cause this?

Phill
Q. Under JOG in axis should the box that has "continues " in it . be able to drop down for jog increments like 5mm,1, 0.1mm etc. If so it is not working on mine.