Controlling motors on same axis separately

Visionary

Is it possible to control three lead screw/ball screw bed setup motors separely to for example babystep to each motor to achieve a level bed or set offsets from three endstops during homing for each motor/screw to have level bed that way.

I think I have rigid enough bed setup to not necessarily need bed leveling sensor.

jay_s_uk

@Visionary only way I know of is to split the axis into 3 individual ones and move them accordingly and then map them back together

dc42

@Visionary yes you can. See https://docs.duet3d.com/en/User_manual/Connecting_hardware/Z_probe_auto_levelling. You can use it without a Z probe by configuring probe type 0.

Visionary

@jay_s_uk
That would work. I just need to change z gcode commands multiaxis commands in gcode but i need to do similar changes anyways for other reasons. Jogging the "real" z height with one press of a button wouldn't be possible with panel due or dwc or can those buttons be changed to take into account other axes?

Visionary

@dc42
I tried this it seemed to work, but is there way to save adjusted motor positions so that the adjustment is not required to be done every machine power up manually?

Note that my machine still needs some parts before I can print so I can't actually verify exact accuracy of the leveling.

jay_s_uk

@Visionary stepper motors move when energised by up to 4 steps so unless they are all fixed together, this isn't something you can "save". Hence why people probe before printing

Visionary

@jay_s_uk

True, but If I homed Z first and then leveled bed manually (with true bed leveling through panel due) while taking notes of the correct offsets of each probe point could I then save those offsets and use them at next power up right after homing to level the bed (skipping the actual true bed leveling part).

jay_s_uk

@Visionary what would those offsets be referenced to? Does each motor have its own endstop?

Visionary

@jay_s_uk

Yes. The bed has 3 ball screws, endstops and motors which each could be adjusted to correct position with offsets

jay_s_uk

@Visionary then yes but you'd have to split the axis out, apply the offset and then rejoin them

Visionary

@jay_s_uk

But wouldn't the motors lose position during switch in axis configuration? Just realized that physical adjustable endstops could do what wanted but those can be difficult to make work well.

jay_s_uk

@Visionary no. That's how RRF2 used to home axis with more than 1 motor