Mini Gerbil debugging – movement

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Symptom DetailLikely causes and their solutions (in recommended sequence)
One of the axes is compressed, elongated, or doesn’t move at allLightburn rotary mode has been left on for that axis…. cancel Lightburn rotary mode
No movement at all!The large 4 pin plug into the Mini Gerbil must supply 24V (LED 7 illuminated) and ground to move the motors.  Check the plug very carefully to ensure contact is being made.  Check wiring.
Check that LED 8 is illuminated to show that the large 4 pin plug is successfully supplying 5V.
Stepsticks need to be replaced – use A4988 stepsticks
Movement occurs on one axis onlyFailed stepstick. To confirm, swap stepsticks, and if proven, replace the failed stepstick.
Laser gantry moves in the wrong direction (although homing is in right direction)Mini Gerbil settings should be checked – see

The home position is incorrectly set in Lightburn or other software.  See

User has non-standard home position.  For inexperienced user, Awesome.Tech very strongly recommend using the standard home position, see
Both job movement and homing are in wrong directionIf the Y axis moves in the wrong direction, set $3=3
if the X axis moves in the wrong direction, set $3=0
If both X and Y axes move in the wrong directions, set $3=2
Making grinding sound while moving (prior to hitting end of gantry range), movement on one or more axes unsuccessful. Difficulty of moving laser head also occurs with K40 powered off completely (at wall). Adjust the K40’s belt tension, see your K40’s instruction manual

The stepsticks need to be adjusted for a higher current, see
Laser head is difficult to move by hand between jobsThis is designed intentionally, to stop the laser losing position between movement.  If necessary, the user can disable via macros in Lightburn.
Movement is poor, slow, jerky, limited or inconsistentCheck for mechanical issues such as incorrect belt tension or obstructions.

Check max feed rate $110=12000, $111=5000 and acceleration settings $120=8000, $121=5000. Too high numbers causes jerky motions or missed steps.

If motion fails only when laser power output is enabled: your high voltage wire to the laser may be shorting to the case and thus disabling all power output. This is very dangerous and a suitably skilled person should insulate your high voltage wire. Note that electrical tape is not sufficient.

Other appliances/devices on same power circuit as K40 & Mini Gerbil causing interference.  Examples: soldering irons, pumps, motors, etc Remove other devices from same circuit and test. Don’t comingle various wires like HT tube lead with control cables.

Mini Gerbil is used with a USB hub, especially one shared with other peripherals like a USB camera. Plug Mini Gerbil and other USB devices into the PC directly, not via a common hub.

Incorrect or corrupted settings. See to ensure default values are used.

The stepsticks need to be adjusted for a higher current, see
Note: stepstick do have thermal shutdown controls, so too high current might stop the motors too until the stepper cools down.

Stepsticks need to be replaced – use A4988 stepsticks

Consider operating temperature. It is normal for stepsticks to be hot, but at some stage the thermal shutdown will initiate. Try adding a fan for cooling. Heatsinks should only be installed if the installer takes care not to short stepstick pins on the heatsink.
Making grinding sound while moving, movement on one or more axes unsuccessfulSwap X-Y axis stepsticks to debug movement.  
Sound heard from stepper motors even when no movementIt is normal for a slight whine to emit from the stepper motors.  This is because they’re energised to stop inadvertant movement, which will result in loss of position. If necessary, motors can be de-energized via a G-code macro.
Grinding sounds occurs when attempting to move at high speed, but slow speed movement usually ok. Movement on one or more axes unsuccessfulCheck belt tension and for mechanical obstructions.  If problem remains, the stepstick current may need adjustment. See
Movement stops part way through jobPC is going into sleep mode during operation.  Change PC settings.

Avoid running a laptop on battery power as this typically forces sleep mode.

PC USB system is going into sleep mode (note: this may not be visible to the user) Review PC settings

The particular file being engraved has curvatures that are incompatible with current GRBL ‘arc tolerance’ settings.  The Mini Gerbil comes with $12=0.002 as a default settings (see what are $ settings), so try tweaking this value to enable your image to be engraved. According to GRBL documentation ( Lower values give higher precision but may lead to performance issues by overloading Grbl with too many tiny lines. While, higher values traces to a lower precision, but can speed up arc performance since Grbl has fewer lines to deal with.

Thermal shutdown of steppers – reduce stepstick current setting or add cooling e.g. fan.

Faulty K40 grounding. See
Movement as expected until laser turns on, then movement stops workingAs the K40’s power supply warms up it loses efficiency, and provides less power than needed. It’s time to replace your K40’s power supply.

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