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Gcode before printing  

Eminent Member
Gcode before printing

Hello you guys I have been using two mk3s for a while now. and also modifying my CR10S for months.

I did install a probe in my CR10S, change the firmware and many componets and it runs so nice. 

I am only having a problem with PRUSASLICER. I have a code that it runs at the start (I am attaching a picture) and I am not exactly sure what it does and why my machine trys to print one straight line of filament (that same thing that CURA does right before start printing) but it goes too much outside the printing could I change that for what the MK3S does? I like that it makes a line around the object right before it prints. I like that better, the MK3S does that, how could I make my CR10S do the same?.

This is what I have for my code right before it starts to print

G28 Y0 X0 Z0 ;
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M104 S[first_layer_temperature] ; set extruder temp
M109 S[first_layer_temperature] ; wait for extruder temp
G29 ; Probe bed before print
M300 S1000 P500 ; chirp     ---------------------------------------this one I have no idea what it means or what it does? Any ideas?
G1 Y-3.0 X0.0 F4000.0 ; go outside print area ----------------this one I have no idea what it means or what it does? Any ideas?
G1 Z0.0 F300.0; ---------------------------------------this one I have no idea what it means or what it does? Any ideas?

Those 3 last lines I dont understand what they do. Can I take them out? or modify them? 

Posted : 19/09/2020 8:56 pm
Famed Member
RE: Gcode before printing

The M300 is to sound a tone.  IIAC, it's 1khz, 1/2 second.

G1 codes are to move the extruder.  The first one has X and Y coordinates, the second has Z.

Posted : 19/09/2020 9:18 pm
Eminent Member
Topic starter answered:
RE: Gcode before printing


Thanks. perfect this helps me a lot. 

I have seen this one a lot G1 Y-3.0 X0.0 F4000.0 ; go outside print area any idea what its really for? 

it does not make much sence to me. 

Thanks again 

Posted : 19/09/2020 9:23 pm
Famed Member
RE: Gcode before printing

The canonical list of the basic gcodes is on line here:

It could be for several things, but it will go to Y -3, which is outside the main print area to the front.

Posted : 19/09/2020 9:31 pm
Illustrious Member
RE: Gcode before printing

The Y-3 section is commonly used for the Mk3 prime line.  Its added to the default mk3 profiles in the start gcode located in Printer Settings Custom gcode section.  Is your cr10 profile from the the Prusa Slicer wizard or ?

I have a cr10s too but I created my own profiles for it was before Prusa started adding non prusa printers.  I have configured my prime line to print up the left hand side from front left corner and back, it then raises, moves to the front left corner again to shear any string and then proceeds with the rest of the start up.

Part of my start up is as follows -

G28 ; Home X/Y/Z axis
G0 X1 Y0 Z0.16 F9000 ; Move in 1mm from edge and up z 0.16mm to give room below nozzle for filament to extrude at feed rate 9000
G92 E0 ; Set extruder to 0 zero
G1 Y145 E50 F500 ; Extrude 50mm filiment along Y axis 145mm long to prime and clean the nozzle at feed rate 500
G92 E0.0 ; Reset extruder to 0 zero end of cleaning run
G1 X3 Y145 Z15 F9000 ; Move over and rise to safe Z height
G1 X3 Y0 Z15 F9000 ; Move back to front of bed at safe Z height to shear strings


The line around the print area is called a skirt and can be set in the Print Settings area.  Its not part of the start gcode.  You will find there are quite a few settings for it.  You can configure how many perimeters, distance from object and also minimum filament to extrude etc.  The skirt can be used for the purposes of priming the nozzle but its also used to make sure that the nozzle height is correct as if it doesn't stick you know something is off.

It can also be configured to be lots of layers and in that instance acts as a draft shield for filaments that need it.

Posted : 19/09/2020 10:05 pm