Here’s a Cold Pull G-code I tried out today. I ran it many times, it didn’t fail a single time. This version doesn’t retract the blob back to the AMS, I ran it with the tubing disconnected from the toolhead.
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; Cold pull G-code for Bambu, the Raz, v2024-02-16
;
; Some observations from the X1C:
; 35 mm from top of toolhead to the extruder gears.
; 50 mm from cutter to nozzle tip.
; 1 mm of filament is 2.41 mm³.
; One push of extrude button is 5 mm (12 mm³).
; 11 pushes (55 mm, 132 mm³) from empty hotend to
; extruding from nozzle. You get about 85 mm of
; thinned filament up/out with the cold pull.
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; Original in Prusa forum with following credits:
; 3dviking.wordpress.com
; use at your own risk.
; modified by C. Rajek
;
; ESUN Cleaning filament: Heat to 255, cool to 95.
; ABS: Heat to 255, cool to 170.
; PLA: Heat to 255, cool to 90.
; PA: Heat to 240, cool to 140.
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M1002 gcode_claim_action : 14 ; "Cleaning nozzle tip"
G28 X Y ; Home XY
G91 ; Relative positioning
G0 Z10 ; Lower bed a little
G90 ; Absolute positioning
M83 ; ...but extruder relative
G0 X128 Y128 ; Position toolhead in the center
M302 S70 P1 ; Allow cold extrusion
M1002 gcode_claim_action : 7 ; "Heating hotend"
M109 S255 ; Heat/wait until 255°C reached
M1002 gcode_claim_action : 14 ; "Cleaning nozzle tip"
G1 E50 F100 ; Extrude 50 mm to fill the nozzle
M106 P1 S255 ; 100% part fan to cool faster
M106 P2 S255 ; 100% aux fan as well
M109 S190 ; Cool/wait to 190°C
G1 E10 F100 ; Extrude another 10 mm in case some oozed out
M109 S70 ; Cool/wait to 70°C
M106 P1 S0 ; Turn off part fan
M106 P2 S0 ; Turn off aux fan
G1 E-200 F1800 ; Retract 20 mm at max. speed (user should pull too)
M104 S0 ; Turn hotend off
M1002 gcode_claim_action : 0 ; Clear message
M84 ; disable steppers - done!
Save this to a file, eg. “Cold_Pull.gcode” and put it in the root directory of the SD card. This way it will always be available for “printing” from the touch screen (I keep a copy of hotbed_tramming.gcode there as well).
It’s easy enough to do this manually but given this seems reliable, I’ll be using it. I assume this would work on P1/A1 series as well but I only tested on X1C.
Edits:
Decreased retraction speed to F1800 (30 mm/s) which is the spec. max. speed for X1C.
Added XY homing for good measure.
Lowered cold temperature to 70°C for better strength of pull.