Pre-printing 3 "dabs"

I’m sure most of you have watched the polyprinters start a print. They begin by preheating the extruder and then go to the front left corner of the bed to deposit 3 little dots to prime the extruder.

My question is: Is this part of the G-code pre-processor script, or is it a function of the KISSlicer software?

I’d like to do something similar for my Ender 3 and using PrusaSlicer, but I’m lazy and don’t want to figure out how to do it myself. :slight_smile:


The ‘Custom Gcode’ option under the ‘printer settings’ tab will let you write in a little bit of gcode to move to a spot on the bed and do any purge operation you want. The slicer will automatically add whatever you enter to the start of the gcode it generates. Just make sure you leave the printer in a state where it can pick up where it left off.

Polyprinter does quite a bit in their start gcode but this is the part for the blobs, of course this may vary on the ender3

G1 Z.50 F240; keep head from melting through tape and causing spurious head contact with bed
G1 X10 Y5 Z.25 F2000
G92 E0
G1 X10 Y0 F1000
G1 E12 F300
G1 Z3  F240
G1 X20 Y5 Z.10 F1000
G1 X20 Y0 F2000
G1 Z.25  F240
G1 E15 F300
G1 Z3  F240
G1 X30 Y5 Z.10 F1000
; retract just a little for the move to the part
G92 E0
G1 E-.5 F300
G1 X30 Y0  F2000
G1 Z.25 F240 ; raise to first layer height to avoid tracking across bed

Thanks to both @michaelb and @themitch22 for the solutions.

I’m currently in the middle of printing a Rowan mask, but I’ll try this out on my next print (after adjusting the code where necessary).

My Prusa’s slicer adds some pre-extrude priming code to the beginning of the GCODE as well: Prusa does a ~100mm line (at two different extrusion rates) rather than PolyPrinter’s three dots, but the benefits are similar.


Note that this code is a template, and allows for the dynamic insertion of certain config parameters like [first_layer_temperature].

Note also that the bed leveling commands G28 and G80, below) may not work properly on your Ender 3.

Other commands (like moving outside the bed area with the G1 Y -0.3 ) also may not work with your Ender 3.

M115 U3.8.1 ; tell printer latest fw version
M83  ; extruder relative mode
M104 S[first_layer_temperature] ; set extruder temp
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 X60.0 E9.0  F1000.0 ; intro line
G1 X100.0 E12.5  F1000.0 ; intro line
G92 E0.0
M221 S{if layer_height==0.05}100{else}95{endif}