Bed level sensor not levelling bed properly


So I finally got my modified A8 back up and running perfectly, but as of about an hour ago the bed level sensor is deciding to not level the bed properly, but only on the left side.
It is using a 9 point grid to level, the 3 centre and 3 right points are levelling perfectly, but all three on the left are measuring about 1mm lower than all the others.
I’ve checked the sensor and it is definitely above the bed. It has been working perfectly for the past week, it’s only this afternoon that it stopped working.
I don’t think its an issue with the sensor as like I say it’s working for the rest of the bed, and the bed is near enough level (well, as well as I can level the stock bed)
Anybody have any ideas as to how I can solve this?


Hi yolosnail,

When you say that the left side is measuring a mm lower, do you mean on the values displayed? This can be caused by the x-axis not being parallel to the bed. Make sure you tram the x-axis and see if that improves your numbers.



I’ve checked and everything is parallel.
What I mean is that it actually crashes into the bed when it’s sensing on the left of the bed


Next guess: are the test points (left side) too close to the edge so they don’t generate as strong a signal? What would happen if you shifted all your points slightly to the right?


I’ve had something similar happen when one of the cables for my probe broke. It would still work on one side of the bed, because the cable was bent and made contact, but when the print head moved to the other side of the bed, the probe lost its connection.


I changed that in the firmware to bring the probe in by an extra 15mm but it didn’t make a difference.

I got the probe on Amazon, so I’ll just file a return and get a replacement sent out, I think I can still get it delivered before Christmas so I’ll give it a go and see if it fixes it