Mini Gerbil with Optical end stops

Optical limit switches (also known as end stops) are occasionally problematic with Mini Gerbil.  This is because K40’s are built in numerous factories and electronically perform differently.  Fortunately there’s a couple of solutions to choose from:


One solution is to change the optical limit switches for mechanical ones.  Some people prefer mechanical limit switches because they don’t suffer from debris blocking the optical path.

A second solution doesn’t involve any additional parts: With your K40 powered off, change the power jumper connector on the Mini Gerbil board from 5Vext to 5VUSB.  Specifically, move the detachable plastic jumper sleeve in the middle of the Mini Gerbil board from the right and centre pins to the left and centre pins.

Easy to change the jumper connector. Note: jumper connector color can vary

Now your Mini Gerbil is powered from your USB.  Each time you operate your K40, you should turn your K40 on before you plug the Mini Gerbil into your PC. Otherwise your Mini Gerbil will try to home, but because the K40 motors are off, a homing error such as Error 8 will appear in the Lightburn console:

Top right console area reports ALARM 8 and $H or $X to unlock

The message will be followed by ‘$H|$X to unlock’.  So turn your K40 on and then type $H {enter} in the console. Your machine will home and your Mini Gerbil’s now ready to run your next cutting/engraving job. If you type $X instead, your Mini Gerbil will be ready for the next job without performing a homing operation.

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