BL-Touch bed leveling seems to produce tilted bed level around Y-axis I have a Tevo Tornado that I've outfitted with an official BL-Touch auto level sensor. I can see the bed probing run, and I can see the Z axis slowly adjust during x/y moves, so it's doing something. However, you can see that there appears to be a systematic tilt:



Any ideas what could be causing this? The bed, gantry and print head is tight, no wobble. Here's my start code:

G28 ; home all axes
G29
G1 Z5 F5000 ; lift nozzle


I have mesh leveling enabled with a 5x5 grid and correct probe offsets. The bed itself is on PETG printed standoffs instead of springs to eliminate any jitter.
The problem with the Tevo Tornado design is that the design is as such that the Z-axis is powered by a single stepper (under the assumption that you have not added a second Z stepper).

This means that the level relies on the rigidity of the X-axis assembly, more specific the play on the guide wheels. Apparently the BL-Touch level determination suffers (the up and down movement while probing) from this design as can be seen from the tilt around the Y-axis direction. This effect causing the tilted level plane is called hysteresis. Now that the Z-axis moves up and down you experience much more problems than using a mechanical switch. The effect is more pronounced when the mass of the hot end carriage is furthest from the Z-axis lead screw.

Note that an extra stepper can also cause tilted level when the second stepper does not move in sync (e.g. missing steps). In such designs, a single stepper (geared) belt driven 2 lead screw has better performance in that respect.