Anycubic Mega S profile damaging bed

[Shorty-CM 1]

A handful of versions back the profile for the Anycubic Mega S changed the start-of-print behaviour to wipe the nozzle at the edge of the bed rather than printing a line slightly inboard of the border.  This seemed like an improvement at the time, but now that location of the bed has begun getting damaged.  It seems as though the edge of the coating has been lifted up or removed now, and that area has slowly been getting larger.  How would I return it to the old behaviour?  I'm assuming this is some change in the pre-print gcode but I do not know what to change or what to change it to.  The behaviour itself probably isn't a problem, but rather the location of it has made it problematic.  If it could be moved inboard from the border slightly again it would probably be fine.  I think it is only an issue because it is doing the wipe right at the edge, and can affect the edge of the bed coating as a result.  I would imagine if it did the same thing a few mm inboard nothing would go wrong.  How would I change the gcode to move it inward a few mm?  Thanks.

[GregValiant 1,408]

I was going to compare the StartUp Gcode from an earlier version to 5.3.1.

I just looked in 5.3.1 and I don't see a Mega S.  Same with 4.13.1 - no Mega S.

So I got stuck.

If you post an old gcode that you liked and a new gcode that you hate (clearly named of course) it only takes a minute to straighten it out.  Less time than it takes to explain for sure.

 

In Cura go to Settings/Printers/Manage Printers and then Machine Settings.  In the lower left is the StartUp Gcode and that's where your problem is.  The best thing to do is get familiar with it yourself.

The Marlin gcode commands are HERE.  A little light reading can go a long ways.  There is no need to memorize them but being familiar with the ones that are used a lot can really help you understand what's going on.

[Shorty-CM 1]

Strange that you don't see the profiles.  Anyway, here is what's currently in my Startup gcode:

 

;Profil Homepage: https://github.com/NilsRo/Cura_Anycubic_MegaS_Profile

;Slicer Information - (Support for OctoPrint Slicer Estimator)
;Slicer info:material_guid;{material_guid}
;Slicer info:material_id;{material_id}
;Slicer info:material_brand;{material_brand}
;Slicer info:material_name;{material_name}
;Slicer info:filament_cost;{filament_cost}
;Slicer info:material_bed_temperature;{material_bed_temperature}
;Slicer info:material_bed_temperature_layer_0;{material_bed_temperature_layer_0}
;Slicer info:material_print_temperature;{material_print_temperature}
;Slicer info:material_print_temperature_layer_0;{material_print_temperature_layer_0}
;Slicer info:material_flow;{material_flow}
;Slicer info:layer_height;{layer_height}
;Slicer info:machine_nozzle_size;{machine_nozzle_size}
;Slicer info:wall_thickness;{wall_thickness}
;Slicer info:speed_print;{speed_print}
;Slicer info:speed_topbottom;{speed_topbottom}
;Slicer info:travel_speed;{travel_speed}
;Slicer info:support;{support}
;Slicer info:retraction_speed;{retraction_speed}
;Slicer info:retraction_amount;{retraction_amount}
;Slicer info:layer_height;{layer_height}
;Slicer info:infill_pattern;{infill_pattern}
;Slicer info:infill_sparse_density;{infill_sparse_density}
;Slicer info:cool_fan_enabled;{cool_fan_enabled}
;Slicer info:cool_fan_speed;{cool_fan_speed}
;Slicer info:sliced_at;{day} {date} {time}
G21                                        ; metric values
G90                                        ; absolute positioning
M82                                        ; set extruder to absolute mode
M900 K0                                    ; disable lin. adv. if not set in GCODE
M107                                       ; start with the fan off
M140 S{material_bed_temperature_layer_0}   ; Start heating the bed
G4 S30                                     ; wait 45 seconds
M104 S{material_print_temperature_layer_0} ; start heating the hot end
M190 S{material_bed_temperature_layer_0}   ; wait for bed
M109 S{material_print_temperature_layer_0} ; wait for hotend
M300 S1000 P500                            ; BEEP heating done
G28 X0 Y10 Z0                              ; move X/Y to min endstops
M420 S1                                    ; Enable leveling
M420 Z2.0                                  ; Set leveling fading height to 2 mm
G0 Z0.15                                   ; lift nozzle a bit
G92 E0                                     ; zero the extruded length
G1 X50 E20 F500                            ; Extrude 20mm of filament in a 5cm line.
G92 E0                                     ; zero the extruded length again
G1 E-2 F500                                ; Retract a little
G1 X50 F500                                ; wipe away from the filament line
G1 X100 F9000                              ; Quickly wipe away from the filament line

 

I see from the comments at the end which lines are responsible for the behaviour.  I presume all I want to do is add a command before the 5 cm line extrusion to move it in Y by 5 mm or something, yes?

 

edit: G0 X5 Y5?  That simple?  Or even just edit the G0 Z0.15 line to include the X and Y moves?

Edited May 7, 2023 by Shorty-CM

[Shorty-CM 1]

Changed:

G0 Z0.15

to:

 

G0 X5 Y5 Z0.15

 

and that seems to have done just what I wanted.  Thanks for the link!

[GregValiant 1,408]

As you've seen - the StartUp Gcode preps the printer to start the print.  It sets some basic parameters, heats the bed and hot end, auto-homes, levels, and in your case runs some filament through and then prints a little bit.

For auto-level systems I think it's best to level with the hot end below print temperature so it doesn't ooze while it's leveling.  I have been known to adjust the feed rate and flow during a print and then forget about it.  When I immediately rolled into another print, it started out with my tuning numbers from the previous print.  Not good.

So here is what I think it needs.  This is just the working code without all the settings you have included in your startup.  You can just throw this out of course, it's your printer.

;

; StartUp Gcode

;

G21                                        ; metric values
G90                                        ; absolute positioning
M82                                        ; set extruder to absolute mode
M900 K0                                    ; disable lin. adv. if not set in GCODE

M220 S100                               ; Reset Feedrate

M221 S100                               ; Reset Flowrate
M107                                       ; start with the fan off
M104 S170                               ; Start to heat the hot end below drool temp
M190 S{material_bed_temperature_layer_0}   ; Heat the bed and wait
G28                                        ; Auto-Home
G1 F600 Z2.0                        ; Move up 2mm
M420 S1                                    ; Enable leveling
M420 Z2.0                                  ; Set leveling fading height to 2 mm

G1 F600 Z5                                ; move up

G1 F3000 X0 Y0                       ; go back to the homing corner to ooze.
M109 S{material_print_temperature_layer_0} ; wait for hotend
G92 E0                                     ; zero the extruded length
G1 X5.0 Y5.0 Z0.3                   ; Move to start of purge line
G1 X102 Y5.0 E20 F1200     ; Extrude 10mm of filament (0.3 * 0.4 * 100)/2.405mm³/mm = 4.98mm so 20 is plenty
G1 F1500 E18                                     ;  retract a bit

G92 E0                                                 ; zero the extruder
G1 F9000 X150 Y2.0 Z1.0                               ; wipe away from the filament line

;

; End of StartUp

;

In the Startup gcode you posted there is that line "G28 X0 Y10 Z0".  G28 with the parameters at zero means "Home if you don't know where you are".  I'm not sure why the "Y10" is there.  It should be Y0 I think.

I've taken out the beep because I personally find it highly annoying.  The printer takes off when it's ready and I always found the visual clue to be enough.

The G4 line goes away because I changed the code to wait for the bed before leveling so the dwell command isn't doing anything.

I changed the layer height of the purge line to .30 since it's a pretty heavy flow and you don't want to hear the extruder skipping steps.

I changed the length of the purge line to 100mm so I made the wipe to 150mm.  If that is bigger than your bed you will need to shorten it.

 

[Shorty-CM 1]

I wondered if that Y10 in there wasn't a typo.  I'm not sure why the person that provided the profile has included the stuff about levelling for a printer that doesn't even do levelling.  Perhaps they've added some levelling system to their printer.  I don't know.  Stock printer doesn't have that functionality anyway.  Thanks again!

[DivingDuck 105]

10 hours ago, GregValiant said:

G1 F1500 E18                                     ;  retract a bit

 

Maybe a typo too?

[GregValiant 1,408]

@DivingDuck at that point it's in "absolute extrusion".

 

@Shorty-CM if you don't have an ABL then you can speed things up buy running both heaters together.  This starts them 10 seconds apart (to keep from stressing the mainboard with the initial current surge).

 

;

; StartUp Gcode

;

G21                                        ; metric values
G90                                        ; absolute positioning
M82                                        ; set extruder to absolute mode
M900 K0                                 ; disable lin. adv. if not set in GCODE

M220 S100                               ; Reset Feedrate

M221 S100                               ; Reset Flowrate
M107                                       ; start with the fan off
M104 S{material_print_temperature_layer_0}                               ; Start to heat the hot end

G4 S10                                                                        ; Wait 10s for the hot end to get going
M140 S{material_bed_temperature_layer_0}                              ; Start to heat the bed

M109 S{material_print_temperature_layer_0}                              ;  Wait for hot end

M190 S{material_bed_temperature_layer_0}                              ; Wait for bed
G28                                        ; Auto-Home
G1 F600 Z12.0                        ; Move up 12mm
G92 E0                                     ; zero the extruded length

G1 F1500 E15                         ; extrude some filament to make sure it's up to the nozzle 

G1 F1500 E13                         ; Short retraction

G92 E0                                     ; Reset extruder

G1 F600 Z0.3                          ; drop down to purge line height
G1 F1500 X5.0 Y5.0 Z0.3       ; Move to start of purge line

G1 F1500 E2                            ; Prime
G1 X105 Y5.0 E22 F1200       ; Purge line
G1 F1500 E20                         ;  retract a bit

G92 E0                                     ; zero the extruder
G1 F9000 X150 Y2.0 Z1.0      ; wipe away from the filament line

;

; End of StartUp

;

 

[Shorty-CM 1]

Thank you!  Yes, I've already been starting the bed first and then the hot-end a few seconds later.  I've been using just a three-second delay, and I'm not sure why the code I pasted before had 30 seconds in it.  The profile came with a 45-second delay, and perhaps I tried lowering it to 30 first and my change to three seconds didn't stick for some reason.  I figured a delay of three seconds might be easier on it with the same line of thought as your 10-second suggestion.  The bed reaches 60 C about five seconds before the hot-end reaches 200 C when started in this manner on this printer.

[GregValiant 1,408]

Nice.  It sounds like you have it sorted out.