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G-Code, CAD, and CAM discussions / Mach3 Plasma Z axis move after firing torch M03

« on: February 16, 2022, 04:58:04 AM »

Hi all,

We have a self built plasma cutter. It uses a PoKeys57CNC Ethernet controller as well as their PlasmaSens unit for THC. We are using a Hypertherm Powermax 45XP source. I'm creating the toolpaths in Fusion360.
Today I was tweaking our machine and noticed that the machine seems to ignore a Z move after firing the torch, below is the sequence that I noted:

• Z probe executes.
• Moves to piece height and fires the torch.
• Waits for the pierce delay, but skips the Z movement to cut height of 1.5mm.
• Machine begins X,Y movements from pierce height and does not first lower to cut height, the height is corrected after moving around 5mm, I assume from the THC input.

When I dry run the machine with THC disabled it functions as expected. If I dry run the machine with THC enabled then it pauses at the M03 command. If I toggle the Torch ON/OFF button it continues and lowers the Z as expected.

Here is a snippet of the G-Code. If you are wondering why there is a 1 second delay before probing we were having issues that the Z axis would frequently move up instead of down when the probe command was executed. Not sure if it is EMF from the motors stopping suddenly, but the 1 second delay solved it.

Code: [Select]

G90
G71

(2D Profile2)
G0 X72.53 Y82.5
G4 P1.
G31 Z-100. F500.
G92 Z-1.7
G0 Z17.3
G0 Z3.8
M3
G4 P1.
G1 Z1.5 F4000.
G1 X68.2 Y80.
G3 X91.8 I11.8 J0.
G3 X68.2 I-11.8 J0.
G1 X72.53 Y77.5
M5
I'm not sure if the THC is somehow interfering with the instructed Z movement once the torch has been fired, not sure how to get around this. I also noticed that I can't really change the Z feedrate without using the 'Lead in' and 'Lead out' feedrates in Fusion360. This also affects the short distance when entering the cut and not the Z movements alone.
Thank you for any help in advance and hopefully I am posting this in the correct section!