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Wipe nozzle via GCODE

Posted by eried 
Wipe nozzle via GCODE
February 02, 2016 08:33PM
Hi!

I am printing with cura and the adhesion is quite bad, if I clean the nozzle it sticks but if I leave it for the initialization (auto-level, etc) the extruded filament just sticks to the nozzle and curls up. This is my start code:

;Sliced at: {day} {date} {time}
;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}
;Print time: {print_time}
;Filament used: {filament_amount}m {filament_weight}g
;Filament cost: {filament_cost}
;M190 S{print_bed_temperature} ;Uncomment to add your own bed temperature line
;M109 S{print_temperature} ;Uncomment to add your own temperature line
G21        ;metric values
G90        ;absolute positioning
M82        ;set extruder to absolute mode
M107       ;start with the fan off
G28 X0 Y0  ;move X/Y to min endstops
G28 Z0     ;move Z to min endstops
M117 Auto-level...
G29        ;auto-level
;G92 Z-.01 ; Lower = Z Pos, Lift = Z Neg
M117 Preparing...
G1 Z10.0 F{travel_speed} ;move the platform down 15mm
G92 E0                  ;zero the extruded length
G1 F100 E30              ;extrude 10mm of feed stock
G92 E0                  ;zero the extruded length again
G1 F{travel_speed}
;Put printing message on LCD screen
M300 S900 P160         ;start beep
M300 S1000 P160
M300 S2000 P160
M0    ;Wait for the user
M117 Printing...

I am using a prusa i3, 190C/60C PLA 1.75, 0.2 mm layer (0.3 mm initial layer), is there any well known gcode to wipe the nozzle? or... is this "self sticking" nozzle problem related with something else? maybe I should apply something to the nozzle like oil? get another nozzle? etc
Re: Wipe nozzle via GCODE
February 02, 2016 10:22PM
It's probably not making a huge difference, but why are you resetting Z zero .01 above what autolevel determined?

10mm of feed stock, with 1.75mm filament and a .4mm nozzle, is going to leave a 191-mm string hanging out of the nozzle (and that g-code will actually extrude three times that). It doesn't surprise me that won't stick. If you want to do a purge like that, your machine needs to have some kind of physical feature that will knock the extruded filament off the nozzle, and you need to drive the head to the location of that feature and move it so it knocks the filament off cleanly during or after the purge. The g-code will depend on what feature you make and where you put it. Most basic RepRaps, instead of doing a purge, just print a skirt first and consider the first part of the skirt a noncritical sacrificial print so the hot end is operating in a stabilized condition before the actual print starts.

Edited 1 time(s). Last edit at 02/02/2016 10:24PM by IMBoring25.
Re: Wipe nozzle via GCODE
February 03, 2016 07:31AM
Hey thanks for answering. I discovered that the nozzle is actual y between .9 and 1 mm! Using some drill bit set. How did you calculated the 191 mm string? I want to check the nozzle size exactly


My printers:
-Makerbot TOM (#5215, circa 2011), MK6 extruder, ABS 3 mm
-HICTOP Prusa i3 (modded for auto-level, thread screws), ABS/PLA 1.75 mm

About me:
[www.thingiverse.com]
Re: Wipe nozzle via GCODE
February 03, 2016 07:42AM
Volume out = volume in

volume of a cylinder = pi*r^2*length
vol out = pi*r^2(out)*L(out)
vol in= pi*r^2(in)*L(in)

pi*r^2(out)*L(out)=pi*r^2(in)*L(in)
r^2(out)*L(out)=r^2(in)*L(in)
L(out)=r^2(in)*L(in)/r^2(out)


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Wipe nozzle via GCODE
February 03, 2016 02:39PM
Yes, I am aware about the conservation of the volume, however is fairly different for the slicer. I noticed that my prints improved a lot after setting 0.9mm as nozzle but I am still trying to hit the sweet spot


My printers:
-Makerbot TOM (#5215, circa 2011), MK6 extruder, ABS 3 mm
-HICTOP Prusa i3 (modded for auto-level, thread screws), ABS/PLA 1.75 mm

About me:
[www.thingiverse.com]
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