Wrong caculation with z_tilt?

General Discussion
1

Hello!

I’m on the way to setup a Formbot T-Rex 3 for Klipper.

All is fine, also stepper_z1 runs well, but…
When I try to run a Z_TILT_ADJUST, I get wierd results:

Recv: // probe at 20.000,200.000 is z=2.243750
Recv: // probe at 20.000,200.000 is z=2.236250
Recv: // probe at 20.000,200.000 is z=2.243750
Recv: // probe at 380.000,200.000 is z=2.593750
Recv: // probe at 380.000,200.000 is z=2.600000
Recv: // probe at 380.000,200.000 is z=2.593750
Recv: // Making the following Z adjustments:
Recv: // stepper_z = -0.238467
Recv: // stepper_z1 = 0.194906
Recv: // Retries: 0/10 Probed points range: 0.354583 tolerance: 0.005000
Recv: // probe at 20.000,200.000 is z=2.488467
Recv: // probe at 20.000,200.000 is z=2.482217
Recv: // probe at 20.000,200.000 is z=2.484717
Recv: // probe at 380.000,200.000 is z=2.832217
Recv: // probe at 380.000,200.000 is z=2.835967
Recv: // probe at 380.000,200.000 is z=2.837217

So, in the first run, Z is -0.238467 too low and Z1 is 0.194906 too high.

So Klipper should add 0.238467 to Z and subtract 0.194906 from Z1.

But in the second run Z is obviously 0.238467 higher than before, but Z1 also is higher instead lower.

This are my Z stepper setups:

[stepper_z]
step_pin: PL3
dir_pin: PL1
enable_pin: !PK0
microsteps: 16
rotation_distance: 4
endstop_pin: probe:z_virtual_endstop
position_min: -4.25
position_max: 500

[stepper_z1]
step_pin: PA5
dir_pin: PA3
enable_pin: !PA7
microsteps: 16
rotation_distance: 4

And this my z_tilt setup:

[z_tilt]
z_positions: 
    -20,200
    420,200
points: 
    20,200
    380,200
speed: 100
horizontal_move_z: 10
retries: 10
retry_tolerance: 0.005

I’m afraid, I missed something.

Any Ideas or experiences?

2

Never mind.

The issue is found: He sits on this side of the keyboard.

I had the wrong cable connected to stepper Z1

grafik

3

I’m pretty sure that many of us have done just that one way or another.

If your bed is not very flat at the specified Y position, you may want to add more probing points along X to get a better overall fit. I do mine with 6 points for example, with the two outer ones on each side being tighter than the inner ones. But if yours work, don’t bother.

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