FAQ

µCNC FAQ (Frequently Ask Questions)

These are a few Q&A that I think may be more common while using µCNC.

Is µCNC safe to use?

• In terms of collisions I think it's has safe has Grbl. Always wire the ESTOP input and it shuts down everything as soon as you press that button. Limit switches triggered with hard limits enabled also prevent unwanted axis crashes.
• In terms of quality of work v1.2.0 is (I believe) capable of deliver reliable results. In any case safety precautions should be implemented. Run the code in check mode to check for GCODE errors and incompatibilities. If still not confident, do a dry run on a scrap peace or in the air to see if everything looks ok. Then run your real job.

Is µCNC a direct replacement for Grbl?

• With minor adaptations yes.
• Pinout yes.
• In terms of settings configuration $0 is max step rate and not step pulse in ms, so for UNO the change is from value 10 to 30000. Everything else should be ok. Eventually $5 and $7 may need adjusting for inverting the limits and controls inputs depending on your wiring.
• If you installed the precompiled version available here then the startup message is with the µCNC name. Some interface software (like Candle, Candle2, and UGS) expect the Grbl startup message instead. If so µCNC needs to be recompiled with option EMULATE_GRBL_STARTUP enabled (cnc_config.h).

Ok I've installed µCNC on my board but nothing is happening. What went wrong?

• If you used a pre-compiled version, as a safety feature all limits and control input pins are pulled high by internal resistors. If µCNC is not wired all limits and control alarms will be active including de Emergency-Stop (ESTOP) input.
• This means that for safety reasons also µCNC will halt. To go around this question short your ESTOP input pin to GND and reconnect your board. µCNC should respond now. If you don't want to use the ESTOP input and want to get rid of the wire, reconfigure setting $7=1 to invert the signal coming from ESTOP, remove the wire and reset your board. µCNC should be running without the wire. At this point other settings may need adjustment.

Ok µCNC is running veeeerrrryyy slooooowwww?

• Like mentioned above setting $0 is max step rate and not step pulse in ms, so for UNO the change is from value 10 to 30000. Restart µCNC and it should start stepping at a proper rate.