Does your K40 grind and causes noise when homing?
When you turn on your K40 laser machine it´s default setting is to home to top left corner and stop.
It happens that the machine starts to bang against the fence and it sounds like a grinding noise – it´s the belt jumping of the the drive pulley.
For some errors you can also see it moves to top but then suddenly starts to move to the right very slow. The cause is the end-stops for both situations.
The reason is actually pretty easy.
On both axis there is a optical end-stop with a metal tab, when it comes in to position the movement stops.
It´s also from this position the machine can calculate where the head is in the machine so it doesn’t run too far right or down.
How to fix it
Make sure the metal pieces are inside the optical end-stop in top left position.
If they are, check all cables and remove the optical end stops and inspect them. It happens that solderings are bad and cracks with time.
I suggest changing to mechanical end stops – article how to do this is being written right now.