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:

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)
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.