CommandCNC Quick‑Start: Load G code Nest → Home → Zero → and Run

A practical checklist for new operators on CandCNC CommandCNC (LinuxCNC‑based). Names/buttons can vary slightly by skin/version.

1. What you need

• G‑code file posted from SheetCam with the CommandCNC/CandCNC post (.tap, .nc, or .ngc).

• Air on & stable, ground clamp secure, water/ventilation as required.

• Controller PC & control cabinet powered, E‑stop released.

2. Power‑up & safety

1. Turn on power and press Green arm button on blade runner box, Release E‑stop in the UI.

2. Verify axis drives are powered (no following error alarms).

3. Check Torch Disable is ON (so it won’t fire) for the first dry run.

If limits are tripped, clear the switch and jog off before homing.

3. Home the machine (reference axes)

1. Click Home All (or Home X, Home Y, Home Z one at a time).

2. Wait for each axis indicator to show Homed.

3. Machine coordinates (G53) are now known; you can safely use automatic moves.

Homing is separate from part zero. Homing = machine’s internal reference; Zeroing = your work coordinate (G54) for the sheet.

4. Load the nest (program)

1. Click Load / Open and browse to your file (USB, network share, local folder).

2. Confirm the preview renders correctly (look for correct size & orientation).

3. Glance at the first lines of code in the editor:

   • G20 = inches, G21 = mm (confirm it matches your intent).

   • Post name/comment should match your machine (e.g., CommandCNC Plasma).

5. Set the work zero (X/Y) on the sheet

1. Jog to your chosen program origin on the sheet—commonly the lower‑left corner.

2. Use Zero X and Zero Y (or Touch Off → set X=0, Y=0). You should now see DROs near X 0.000, Y 0.000.

3. Jog Z to a safe height over the sheet.

Plasma Z is usually not manually zeroed because IHS/float‑switch/ohmic finds surface at each pierce. Leave Z to the post unless your post requires an initial touch.

6. Torch height control (THC) & test

• Keep Torch Disable = ON for a dry run.

• Ensure THC is in Auto/Enabled for real cuts (many posts turn THC on after arc‑ok and pierce).

• Optional: in MDI, you can test motion only (never fire torch in the air). Avoid manual M3 unless you’re in a safe test position.

7. Dry‑run the path (Torch Disabled)

1. With Torch Disable ON, press Cycle Start.

2. Watch the motion: leads, order (holes before perimeter), clearance, and bounds.

3. If anything looks off, Feed Hold, Stop, adjust zero/rotation, or reload the correct program.

8. Run the job (Torch Enabled)

1. Return to X/Y zero if you moved; verify DROs are ~0,0 at your origin.

2. Turn Torch Disable OFF (torch may now fire under program control).

3. Hand on Feed Hold. Press Cycle Start.

4. Observe the first pierce:

   • IHS probe → pierce height/delay → cut height → THC engages after arc‑ok.

5. Use Feed Override slider/knob for small adjustments; avoid large changes mid‑hole.

9. Pause, resume, and restart mid‑program

• Pause / Feed Hold to stop motion cleanly. Resume continues.

• To restart after an interruption:

  1. Stop program. Make sure the part & torch are clear.

  2. Use Start From Line / Run From Here (if provided): select the next lead‑in line before the missed feature.

  3. Confirm the previewed move; system will position to the selected start.

  4. Torch Disable ON for a quick dry‑position check, then OFF to actually cut.

If you lost position or power, you may need to re‑home, jog back to your sheet origin, and re‑zero X/Y before using “Start From Here”.

10. After the cut

• Torch Disable ON. Jog clear. Park the gantry.

• Note run time/pierce count if you track consumables.

• Save any useful offsets/templates.

11. Common pitfalls & fixes

• Cycle Start does nothing: E‑stop active, not Machine ON, or not homed.

• Wrong size: G20/21 mismatch. Repost in correct units.

• Starts at wrong corner: X/Y zero set in the wrong place—re‑zero at the intended origin.

• Dives/hunts on small holes: Use SheetCam small‑feature rules to slow and THC off; confirm pierce height/delay.

• Torch won’t fire: Torch Disable still ON; air pressure low; Arc‑OK wiring/inputs; check post is for CommandCNC.

• Out of travel: Nest too large or zero placed too near a limit. Re‑zero or reposition sheet.

12. Quick reference (terms)

• Home (G53): Machine’s internal reference after homing.

• Zero / Touch‑off (G54): Your job origin on the sheet.

• IHS (Initial Height Sense): Probes surface each pierce (ohmic/float).

• THC: Adjusts Z to maintain arc voltage during cut.

• Cycle Start / Feed Hold / Stop: Run, pause, and abort controls for the interpreter.