Homing failed, computed corrections exceed limit

[Steppenleguan]

Hey guys,

I recently swapped out my dual endstops on my bed for a BL Touch - goal is to achieve ABL and getting a mesh grid of my bed.

Homing XY is working just fine, but Z Axis (I am using dual leadscrews in the middle of the bed, left&right) is making trouble. After having finished the XY home sequence, the gantry is moving to the first probing point just fine and homing with BL Touch.
It´s then moving up the bed to home the 2nd point., where after the bed descends a whole lot and homing fails.

2 problems:

1. The bed is descending around 75-85 mm after the first probe point (I would like to reduce that, but I can´t seem to find how)
2. Homing fails: Error: Some corrupted corrections exceed configured limit of 1.0mm: -75.040 -75.380

I have a feeling that, genereally that this is only a minor problem, as the limits are only 0.3 mm apart, so I´m hoping for an easy fix.

This is the bed.g:

; bed.g
; called to perform automatic bed compensation via G32
;
; generated by RepRapFirmware Configuration Tool v3.2.3 on Sun Apr 04 2021 15:17:44 GMT+0200 (Mitteleuropäische Sommerzeit)
;G29  ; probe the bed and enable compensation
 
G28 ; home
 
M561 ; clear any bed transform
 
;M671 P5.0 X365.0:365.0 Y3-32:762 ; Z pivot points are at (340:-32) (340:712) 712 = 680+32
 
G30 P0 X365.0 Y100 Z-9999 ;PROBE NEAR A Front LEADSCREW
;G1 F60000 X20 Y235 Z10
G30 P1 X365.0 Y630 Z-9999 S2 ;PROBE NEAR A Back LEADSCREW

config.g :

M569 P0 S1 ; Drive 0 X 
M569 P1 S1 ; Drive 1 Y
;M569 P2 S0 ; Left z-motor (original Z) 												; NOT USED
M569 P3 S1 ; Drive3 [Extruder 0] - new Extruder 0 [ENABLED]
M569 P4 S1 ; Drive4 [Extruder 1] - new Extruder 1 [ENABLED]
 
M569 P5 R1 T2.5:2.5:5:5 S0 ; BreakoutBoard_Driver5 - new Z Axis || Von Steuerkiste hinten 
M569 P6 R1 T2.5:2.5:5:5 S0 ; BreakoutBoard_Driver7 - new Z Axis || Von Steuerkiste vorne 
 
; M569 P7 S1 ; Extruder2 - Physical Tool 2
; M569 P8 S1 ; Extruder3 - Physical Tool 3
; M569 P9 S1 ; Extruder4 - Physical Tool 4  
 
M584 E3 E4										; set drive mapping Driver  Extruder 3, Extruder 4
M584 X0 Y1 Z5:6 P3   							; set drive mapping Driver 0 For X, 1 for Y,  Z 5:7, with 4 Axis (exkl. Extruders) visible in UI
;M671 P5.0 X0:700 Y0:700 S2.5 					; leadscrews at left (connected to Z) and right (connected to E1) of X axis
M671 P5.0 X365.0:365.0 Y-32:762 S1; Z pivot points 
 
; Z-Probe
M574 Z2 S2 P"bltouch" 							; Z min active high endstop z-probe
M950 S0 C"!exp.heater7"                         ; create servo pin 0 for BLTouch on Duet 2 Wifi + Expansion Board
M558 P9 C"^zprobe.in" H5 F120 T6000             ; set Z probe type to bltouch and the dive height + speeds
G31  P500 X43 Y-47.8 Z3.36                             ; set Z probe trigger value, offset and trigger height
;M557 X20:710 Y20:710 S20                       ; define mesh grid
 

homez.g:

G91 ; relative position
G1 Z9 F6000 S2 ; lower z by 9
G90 ; absolute position
 
G30 P0 X365 Y100 Z-9999 ; probe point 0 near a leadscrew
G30 P1 X365 Y630 Z-9999 S2; probe point 1 near a leadscrew
;G1 Z-15 F5000 ; raise z to 15
 
 
 
G90               ; absolute positioning

Thanks for your help. I genereally understand the problem of the 2 axis not being able to compensate for 75 mm each, but in this case it doesn´t make any sense to me, as the bed is pretty level already.

[Phaedrux]

Post your full config.g and homeall.g as well please.

Also please post the results of M122 and M98 P"config.g"

@Steppenleguan said in Homing failed, computed corrections exceed limit:

; Z-Probe
M574 Z2 S2 P"bltouch"

Remove that M574 line entirely.

@Steppenleguan said in Homing failed, computed corrections exceed limit:

M950 S0 C"!exp.heater7"

I don't think you should have a ! there. It's inverting the pin when it shouldn't be.

This is what I get from the config tool.

; Z-Probe
M950 S0 C"exp.heater7"                         ; create servo pin 0 for BLTouch
M558 P9 C"^zprobe.in" H5 F120 T6000            ; set Z probe type to bltouch and the dive height + speeds

In your homez you're not homing Z first, you're going straight into tilt correction. Where do you home z?

[Steppenleguan]

This post is deleted!

[Steppenleguan]

@Phaedrux thanks for the help, I added the home sequence and its working fine now Also I had the drives in the wrong order so the compensation was wrong at first, too.