Three thumps during homing

New thumping during homing as you can hear in the video. Only thumps three times then Machine works perfectly after that, but it doesn’t sound right. What belt, switch should I be checking? Any other video you would like me to add?

Perhaps your proximity switch is a little low. I have a 3 XXL and when I upgraded to proximity switches the instructions had you set the switch quite high and on initial initialization it failed. I had to set the X switch lower so it was triggered properly. It may be that your switch is not being triggered and the 3 bumps are the slipping of the belts and then timing out and giving up.

Have you tried to adjust the switch so it is closer to the trigger?

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It seems like one of the switches is not getting triggered immediately upon the second (slow) move in the homing sequence, while all three triggered just fine upon the initial fast approach.

Since the two switches seen in the videos seems to light up correctly, I wonder if it could be the Z switch, can you observe whether it lights up during the retract-and-home-in-slowly phase before the thumps ?

Anyway likely a case of a switch that is positioned just so that it triggers at the exact same time there is mechanical contact, and then it’s a race between the two and maybe after losing steps bumping into the end two or three times, it finally triggers. Try and reposition the switches ever so slightly so that you have more margin to ensure the switches always trigger a little bit before mechanical contact happens.


It was the homing switches. The issue is that the z proximity switch has two switches at the front that we all talk about, but also one at the back. Tightened that and perfect sounding initialisation.