Automatic Bed Leveling with Conditional Gcode Iterations

Kolbi

This is a long and winding thread on my attempt to figure out the best way to construct beg.g for my independent controlled Z axis printer. Bottom line up front, two efficient ways were created to do such.

; bed.g
; called to perform automatic bed compensation via G32
; 4 Passes performed. Reccomend 2 passes as minimum.
 
M561                                             ; clear any bed transform
G28                                              ; home
 
while iterations <= 3                            ; perform 4 passes
    G30 P0 X25 Y100 Z-99999                      ; probe near a leadscrew, half way along Y axis
    G30 P1 X235 Y100 Z-99999 S2                  ; probe near a leadscrew and calibrate 2 motors
    G90                                          ; back to absolute mode
 
G1 H2 Z8 F2600                                   ; raise head 8mm to ensure it is above the Z probe trigger height
G1 X104 Y100 F6000                               ; put head over the centre of the bed, or wherever you want to probe
G30

and

; 0:/sys/bed.g
; Called to perform automatic bed compensation via G32

M561                                                       ; Clear any existing bed transform.
G28                                                        ; Home all axis.

M558 F50 A5 S0.003                                         ; Slow z-probe, up to 5 probes until disparity is 0.003 or less - else yield average.
while iterations <=2                                       ; Perform 3 passes.
   G30 P0 X25 Y105 Z-99999                                 ; Probe near a leadscrew, halfway along Y-axis.
   G30 P1 X225 Y105 Z-99999 S2                             ; Probe near a leadscrew and calibrate 2 motors.
   G1 X105 F10000                                          ; Move to the center of the bed.
   G30                                                     ; Probe the bed at the current XY position.
   M400                                                    ; Finish all moves, clear the buffer.

M558 F50 A5 S-1                                            ; Slow the z-probe, perform 5 probes and yield the average.
while move.calibration.initial.deviation >= 0.003          ; Perform additional leveling if previous deviation was over 0.003mm. 
   if iterations = 5                                       ; Perform 5 addition checks, if needed.
      M300 S3000 P500                                      ; Sound alert, the required deviation could not be achieved.
      M558 F200 A1                                         ; Set normal z-probe speed.
      abort "!!! ABORTED !!! Failed to achieve < 0.002 deviation. Current deviation is " ^ move.calibration.initial.deviation ^ "mm."
   G30 P0 X25 Y105 Z-99999                                 ; Probe near the left leadscrew, halfway along Y-axis.
   G30 P1 X225 Y105 Z-99999 S2                             ; Probe near the right leadscrew and calibrate 2 motors.
   G1 X105 F10000                                          ; Move the nozzle to the center of the bed.
   G30                                                     ; Probe the bed at the current XY position.
   M400                                                    ; Finish all moves, clear the buffer.

M558 F200 A1                                               ; Set normal z-probe speed.
echo "Gantry deviation of " ^ move.calibration.initial.deviation ^ "mm obtained."
G1 Z8                                                      ; Raise nozzle 8mm to ensure it is above the Z probe trigger height.

-Original post follows:
I was looking into the M30 command & bed.g file, in regards to leveling the gantry, and had a question. I usually find I have to run the below (G30 set twice as shown) to get to a low disparity, such as:

G30 P0 X25 Y100 Z-99999                          ; probe near a leadscrew, half way along Y axis
G30 P1 X235 Y100 Z-99999 S2                      ; probe near a leadscrew and calibrate 2 motors
G90
G30 P0 X25 Y100 Z-99999                          ; probe near a leadscrew, half way along Y axis
G30 P1 X235 Y100 Z-99999 S2                      ; probe near a leadscrew and calibrate 2 motors
G90                                              ; back to absolute mode

This works fine but could the same, or possible more accurate, be accomplished like this?

G30 P0 X25 Y100 Z-99999                          ; probe near a leadscrew, half way along Y axis
G30 P1 X235 Y100 Z-99999                         ; probe near a leadscrew and calibrate 2 motors
G30 P2 X25 Y100 Z-99999                          ; probe near a leadscrew, half way along Y axis
G30 P3 X235 Y100 Z-99999 S4                      ; probe near a leadscrew and calibrate 2 motors
G90                                              ; back to absolute mode

Cheers,
Kolbi

Phaedrux

If that did work, I don't think it would be more accurate. Plus I don't think that would work as expected.

Doubling up the passes in bed.g isn't uncommon. It will really depend on how out of true the tilt is and how close to the lead screws you can probe.

Kolbi

Thanks @Phaedrux, was just wondering if there was a better way to skin the cat.

Phaedrux

I'd probably do it 3 times for good measure and then at the end probe the center of the bed with G30 to re-establish Z0. But that's just me.

Kolbi

@Phaedrux hehe, this is my bed.g:

; bed.g
; called to perform automatic bed compensation via G32
; 4 Passes performed. Reccomend 2 passes as minimum.

M561                                             ; clear any bed transform
G28 W                                            ; home

G30 P0 X25 Y100 Z-99999                          ; probe near a leadscrew, half way along Y axis
G30 P1 X235 Y100 Z-99999 S2                      ; probe near a leadscrew and calibrate 2 motors
G90                                              ; back to absolute mode

G30 P0 X25 Y100 Z-99999                          ; probe near a leadscrew, half way along Y axis
G30 P1 X235 Y100 Z-99999 S2                      ; probe near a leadscrew and calibrate 2 motors
G90                                              ; back to absolute mode

G30 P0 X25 Y100 Z-99999                          ; probe near a leadscrew, half way along Y axis
G30 P1 X235 Y100 Z-99999 S2                      ; probe near a leadscrew and calibrate 2 motors
G90                                              ; back to absolute mode

G30 P0 X25 Y100 Z-99999                          ; probe near a leadscrew, half way along Y axis
G30 P1 X235 Y100 Z-99999 S2                      ; probe near a leadscrew and calibrate 2 motors
G1 H2 Z8 F2600                                   ; raise head 4mm to ensure it is above the Z probe trigger height
G90                                              ; back to absolute mode

G1 X104 Y100 F6000                               ; put head over the centre of the bed, or wherever you want to probe
G30                                              ; lower head, stop when probe triggered and set Z to trigger height

Kolbi

@Phaedrux A cleaner way to do it:

; bed.g
; called to perform automatic bed compensation via G32
; 4 Passes performed. Reccomend 2 passes as minimum.

M561                                             ; clear any bed transform
G28                                              ; home

while iterations <= 3                            ; perform 4 passes
    G30 P0 X25 Y100 Z-99999                      ; probe near a leadscrew, half way along Y axis
    G30 P1 X235 Y100 Z-99999 S2                  ; probe near a leadscrew and calibrate 2 motors
    G90                                          ; back to absolute mode

G1 H2 Z8 F2600                                   ; raise head 8mm to ensure it is above the Z probe trigger height
G1 X104 Y100 F6000                               ; put head over the centre of the bed, or wherever you want to probe
G30

Phaedrux

Now you're cooking with gas!

mwolter

@Kolbi

Since you're delving into conditional gcode you could look at something like this which only continues probing if necessary. Apologize for the length of this post but I included all sub macros for completeness. homexy.g also uses a virtual tool to indicate homing is in progress to avoid unnecessary Z axis movement. In case you're wondering, the sub macros are used to reduce duplicate code and unnecessarily updating several macros.

if !move.axes[0].homed || !move.axes[1].homed	; If the printer hasn't been homed, home it
 M98 P"0:/sys/homeyx.g"	; home y and x
;
M98 P"0:/sys/homez.g"			; always home z
;
M561					; clear any bed transform
M558 P9 H5 F120 T24000			; increase dive height incase bed is severely out of alignment
M98 P"bed_threeScrews.g"		; perform bed tramming
echo "Bed Tramming Cycle: 1 - Difference was " ^ move.calibration.initial.deviation ^ "mm"
;
M98 P"0:/macros/Utilities/Config/bltouch_config"	; Apply default BLTouch config
;
while move.calibration.initial.deviation >= 0.01	; perform additional tramming if previous deviation was over 0.01mm
 if iterations = 5
  abort "Too many auto tramming attempts"
 M98 P"bed_threeScrews.g"				; perform bed tramming
 echo "Bed Tramming Cycle: " ^ iterations + 2 ^ " - Difference was " ^ move.calibration.initial.deviation ^ "mm"
 continue
;
G28 Z							; home z

bltouch_config

M558 P9 C"^io7.in" H2 F120 T24000 	; set Z probe type to bltouch and the dive height + speeds
;
M98 P"0:/macros/Utilities/Config/bltouch_offset_config"

bltouch_offset_config

;
; G31 - +Z Nozzle closer to bed, -Z Nozzle further from bed
;
G31 X0 Y-20.23 Z2.1 P500		; 200710 mosquito liquid

bed_threeScrews.g

G30 P0 X10 Y18 Z-99999			; probe near a front left leadscrew
G30 P1 X10 Y300 Z-99999			; probe near a back left leadscrew
G30 P2 X320 Y166 Z-99999 S3		; probe near a right leadscrew and level

homexy.g

; homeyx.g
; called to home x and y axes
;
; Warning: do not home individual axes by calling G28 X or G28 Y. It will cause errors. Instead run the macro file directly. IE M98 P"0:/sys/homex.g"
;
M563 P9 S"HomeAll"		; create tool 9 to indicate homeall is in progress
;
G91              		; relative positioning
G1 Z5 F6000 H2   		; lift Z relative to current position
M98 P"0:/sys/homey.g"		; home y
M98 P"0:/sys/homex.g"		; home x
G90             		; absolute positioning
;
M563 P9 D-1 H-1			; delete tool 9 to indicate homeall is done

homex.g

if #tools != 10	; not homeall?
  G91              ; relative positioning
  G1 Z5 F6000 H2   ; lift Z relative to current position
;
G1 H1 X357 F6000 ; move quickly to X axis endstop and stop there (first pass)
G1 X-5 F3600     ; go back a few mm
G1 H1 X357 F360  ; move slowly to X axis endstop once more (second pass)
;
if #tools != 10	; not homeall?
  G1 Z-5 F6000 H2  ; lower Z again
  G90              ; absolute positioning

homez.g

if #tools != 10	; not homeall?
  G91			; relative positioning
  G1 Z5 F6000 H2	; lift Z relative to current position
  G90			; absolute positioning
;
; Home Z - inline with autolevel axis
G1 X165 Y193 F24000	; go to middle of the bed probe point and home Z. BLTouch on right
M558 F1200		; Set probing at faster feed rate
G30			; quickly home Z by probing the bed
M400			; clear buffer
M98 P"0:/macros/Utilities/Config/bltouch_config"	; Return bltouch to defaults
G30			; slowly home Z by probing the bed
M400			; clear buffer

Phaedrux

@mwolter Beautiful.

Kolbi

@mwolter Nice, thanks for that.

Being away from my printer at the moment, but I would guess the following would be a correct implementation for my dual Z setup:
!!! Please see my final code, this is not correct !!!

; bed.g
M561                                                    ; clear any bed transform
G28                                                     ; home
while move.calibration.initial.deviation >= 0.01	; perform additional tramming if previous deviation was over 0.01mm

 if iterations = 5                                      ; perform 5 checks
  abort "!!!Failed to achieve < 0.01 deviation within 5 movements. Current deviation is " ^ move.calibration.initial.deviation ^ "mm."

    G30 P0 X25 Y100 Z-99999                             ; probe near a leadscrew, half way along Y axis
    G30 P1 X235 Y100 Z-99999 S2                         ; probe near a leadscrew and calibrate 2 motors
    G90                                                 ; back to absolute mode

 echo "Bed Tramming Cycle: " ^ iterations + 2 ^ " - Difference was " ^ move.calibration.initial.deviation ^ "mm"
 continue

;

fcwilt

@mwolter said in Automatic Bed Leveling with Conditional Gcode Iterations:

G1 Z{move.axes[2].userPosition+20} F1200

Hi,

Why that command as opposed to G91 G1 Z20?

And why did you implement homing such that you could not safely use G28 X or G28 Y?

It would not be hard to structure it so you could.

Thanks.

Frederick

mwolter

@fcwilt Using that command I can be sure it raised 20mm from the previous height. Probably overkill It was a quick add before posting this and thought it would help with changing the magnetic bed but it makes for an odd extra movement of the bed between performing the homez and bed leveling. I'll rework the macros to utilize the virtual homeall tool to skip the unnecessary bed movement and update the macros above.

mwolter

@Kolbi There are too many spaces before the G30 commands and it would cause issues. Would recommend doing one leveling pass before the while command. I haven't tested the following code but it should be close.

M561                                         ; clear any bed transform
G28                                          ; home
G30 P0 X25 Y100 Z-99999                      ; probe near a leadscrew, half way along Y axis
G30 P1 X235 Y100 Z-99999 S2                  ; probe near a leadscrew and calibrate 2 motors
echo "Bed Tramming Cycle: 1 - Difference was " ^ move.calibration.initial.deviation ^ "mm"

while move.calibration.initial.deviation >= 0.01	; perform additional tramming if previous deviation was over 0.01mm
 if iterations = 5
  abort "Too many auto tramming attempts"
 G30 P0 X25 Y100 Z-99999                      ; probe near a leadscrew, half way along Y axis
 G30 P1 X235 Y100 Z-99999 S2                  ; probe near a leadscrew and calibrate 2 motors
 echo "Bed Tramming Cycle: " ^ iterations + 2 ^ " - Difference was " ^ move.calibration.initial.deviation ^ "mm"
 continue
G28 Z					; home z

Kolbi

@mwolter Thanks for covering my 6, I just caught that and was typing this:
!!! Please see my final code, this is not correct !!!

; bed.g
; Called to perform automatic bed compensation via G32
M561                                                    ; clear any bed transform
G28                                                     ; home

G30 P0 X25 Y100 Z-99999                                 ; probe near a leadscrew, half way along Y axis
G30 P1 X235 Y100 Z-99999 S2                             ; probe near a leadscrew and calibrate 2 motors

while move.calibration.initial.deviation >= 0.01	; perform additional tramming if previous deviation was over 0.01mm
 
 if iterations = 5                                      ; perform 5 checks
  abort "!!!Failed to achieve < 0.01 deviation within 5 movements. Current deviation is " ^ move.calibration.initial.deviation ^ "mm."
 
 G30 P0 X25 Y100 Z-99999                                ; probe near a leadscrew, half way along Y axis
 G30 P1 X235 Y100 Z-99999 S2                            ; probe near a leadscrew and calibrate 2 motors
 G90                                                    ; back to absolute mode
 
 echo "Gantry deviation of " ^ move.calibration.initial.deviation ^ "mm obtained within " ^ iterations + 2 ^ " tramming cycles."
 continue
 
;

Kolbi

@mwolter I guess the trailing code is not a hard requirement? By trailing code I'm referring to this:

 continue

 
;

mwolter

@Kolbi nope

mwolter

Removed the following and added it to homeall.g since I typically do a home all before changing the bed.

G1 Z{move.axes[2].userPosition+20} F1200		; move z up 20mm for magnetic bed replacement

homeall.g

; homeall.g
; called to home all axes (G28)
;
; Warning: do not home individual axes by calling G28 X or G28 Y. It will cause errors. Instead run the macro file directly. IE M98 P"0:/sys/homex.g"
;
M563 P9 S"HomeAll"		; create tool 9 to indicate homeall is in progress
;
G91              		; relative positioning
G1 Z5 F6000 H2   		; lift Z relative to current position
M98 P"0:/sys/homey.g"	; home y
M98 P"0:/sys/homex.g"	; home x
G90             		; absolute positioning
;
M98 P"0:/sys/homez.g"	; home z
;
M563 P9 D-1 H-1			; delete tool 9 to indicate homeall is done
;
G1 Z{move.axes[2].userPosition+50} F1200		; move z up 50mm for magnetic bed replacement

Kolbi

Thanks @mwolter!

For brevity, here is my final working version:

; bed.g
; Called to perform automatic bed compensation via G32

M561                                                      ; Clear any bed transform
G28                                                       ; Home

while iterations <=1                                      ; Do minimum of 2 passes
   G30 P0 X25 Y100 Z-99999                                ; Probe near a leadscrew, half way along Y axis
   G30 P1 X235 Y100 Z-99999 S2                            ; Probe near a leadscrew and calibrate 2 motors
   G90

while move.calibration.initial.deviation >= 0.002         ; perform additional tramming if previous deviation was over 0.002mm 
   if iterations = 5                                      ; Perform 5 checks
      M300 S3000 P500                                     ; Sound alert, required deviation could not be achieved
      abort "!!! ABORTED !!! Failed to achieve < 0.002 deviation within 5 movements. Current deviation is " ^ move.calibration.initial.deviation ^ "mm."
   G30 P0 X25 Y100 Z-99999                                ; Probe near a leadscrew, half way along Y axis
   G30 P1 X235 Y100 Z-99999 S2                            ; Probe near a leadscrew and calibrate 2 motors
   G90                                                    ; Back to absolute mode

echo "Gantry deviation of " ^ move.calibration.initial.deviation ^ "mm obtained."
G1 H2 Z8 F2600                                            ; Raise head 8mm to ensure it is above the Z probe trigger height
G1 X104 Y100 F6000                                        ; Put head over the centre of the bed, or wherever you want to probe
G30

fcwilt

@mwolter said in Automatic Bed Leveling with Conditional Gcode Iterations:

@fcwilt Using that command I can be sure it raised 20mm from the previous height.

Hi,

Thanks for the reply.

Why do you think G91 G1 Z20 doesn't do that same thing?

Frederick

mwolter

@fcwilt
It’s just a different way of doing it and like I mentioned, this way I can be sure it’s raised 20mm from its current position. The G30 command actually sets Z to about 3m. So G1 Z20 will only raise Z by 17mm.