Automatic Bed Leveling with Conditional Gcode Iterations

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.

Kolbi

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

Now you're cooking with gas!

Definitely cooking with gas now!

fcwilt

@mwolter said in Automatic Bed Leveling with Conditional Gcode Iterations:
The G30 command actually sets Z to about 3m. So G1 Z20 will only raise Z by 17mm.

I think you will find that a G91 G1 Z20 will raise Z by 20 unless it doesn't have that much room left on the axis.

If a G30 sets Z to 3 then a G91 G1 Z20 will take Z to 23.

At least that is my experience.

Good luck.

Frederick

mwolter

This post is deleted!

Phaedrux

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

I think you will find that a G91 G1 Z20 will raise Z by 20 unless it doesn't have that much room left of the axis.

Correct. G90 moves to an absolute point, G91 is relative to the current position.

https://duet3d.dozuki.com/Wiki/Gcode#Section_G90_Set_to_Absolute_Positioning

mwolter

@Phaedrux If the command G90 G1 Z20 is used in one line, does G91 have to be used to return to absolute mode?

Phaedrux

@mwolter That's a good question, and I'm not sure off the top of my head. Would have to test to see if it sticks in that format or not.

Kolbi

Another thing I noticed is repeatability with PindaV2 probe is not as consistent as BLTouchV3.1... So being that I use a bondtech bmg mosquito, I've made this modified version to scrap the Pinda and welcome the BLTouch. Will get it sorted on the printer and test it fully this weekend.

mwolter

@Kolbi looks good! Is that SLS or MJF printed?

Kolbi

@mwolter It was done on an HP Multijet Fusion (MJF), using Nylon PA12.

A Former User

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

If the command G90 G1 Z20 is used in one line, does G91 have to be used to return to absolute mode?

yes, g-code knows nothing about white space or line breaks

(optionally you can use push and pop, M120, M121)

fcwilt

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

@Phaedrux If the command G90 G1 Z20 is used in one line, does G91 have to be used to return to absolute mode?

G90 is absolute, G91 is relative.

Frederick