⚠️ Experimental If you want to use this be aware that I take no responsibility if you damage your printer in the process of using it. ⚠️

Since Discord decided to disable my old account I had to setup a new one (nima#8307).

This is a proof of concept for the BLV MGN Cube and a CR10 style bed.

Essentially I replaced the wheels with NEMA 17 stepper motors which are mounted with a printed part and control the height of the corner using a special printed coupler as well as a brass insert.

If you want to try that setup out on your own printer you can either use the STL files if you have the same printer and bed or adjust the step files for your own.

To use the macro you have to add and customize the following lines in your printer.cfg:

[screws_tilt_adjust]
screw1: 68.48,40
screw1_name: Lower Left
screw2: 308.48,280
screw2_name: Upper Right
screw3: 68.48,280
screw3_name: Upper Left
screw4: 308.48,40
screw4_name: Lower Right
horizontal_move_z: 10
screw_thread: CW-M3

The M3 screws I'm using for tramming the bed have a pitch of 0.5 mm which simply translates to a rotation distance of 0.5 in the config file for each of the stepper motors.

Usage

After running G28 and SCREWS_TILT_CALCULATE you will get an output similar to this:

01:20 means 1 full turn and 20 minutes, CW=clockwise, CCW=counter-clockwise
Lower Left (base) : x=68.5, y=40.0, z=2.40900
Upper Right : x=308.5, y=280.0, z=2.41150 : adjust CCW 00:00
Upper Left : x=68.5, y=280.0, z=2.40775 : adjust CW 00:00
Lower Right : x=308.5, y=40.0, z=2.40650 : adjust CW 00:00

Now you can adjust the screws by calling the ADJUST_SCREWS macro with the values from the output above:

ADJUST_SCREWS BASE=2.40900 UR=2.41150 UL=2.40775 LR=2.40650

Do this until SCREWS_TILT_CALCULATE MAX_DEVIATION=0.01 doesn't output !! bed level exceeds configured limits (0.01mm)! Adjust screws and restart print. anymore but remember to home the Z axis before that each time.

I would advise adding a G28 as well as SCREWS_TILT_CALCULATE MAX_DEVIATION=0.01 to the end of the macro to automate the process until the desired result is reached.

What's next?

I am working on further automating the process by having Klipper loop over the commands and adjusting the stepper motor positions by itself. This way you could just add a macro call to always have a perfectly trammed bed before each print.

I added a little hack to the screws_tilt_adjust.py file to output the command as well as automatically calling the macro to adjust the screws. It works for now but I will further work on implementing it the right way.

Replacing the original file with the custom one found in this repository and restarting the Pi should be enough to enable that functionality but just to be sure I also deleted the .pyc file to be generated again after booting up. Keep in mind that it relies on the fact that there are 4 motors and one would need to change the macro as well as the variables in the code to change the amount of motors used for now.