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

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

[strike]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 [/strike]
Edit3: fixed...

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

[strike]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 [/strike]
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. :woohoo:

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

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

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?

I think you are using floating switch for probing, right ?
In that case the "float travel" is set to high. If it still stays high during cut, lower the voltage or disable "auto volts".

On a probe test:

• Z down at Setup Seed (Config Panel) to Probe Height (Config Panel)
• Z down at Probe Speed (Config Panel) until contact detected
• Z up at .001mm (0.00004") until contact lost. This is then Z0
• Z up at Setup Speed to Pierce Height (Run Panel)
• Wait for amount of seconds in ini file (BUTTON_n_CODE = probe-test 30). This allows time to check the height.
• Z up at Setup Speed to where it started from.

Notes:

• The DRO display for Z in the GUI has no relationship to any of the heights that PlasmaC uses.
• Probe Height is the height above the Z axis minimum limit.

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.

Yes, there should be a JOG_INCREMENTS setting in the [DISPLAY] section of the .ini file.