Strange behavior when changing start g-code
Over on this thread on reddit, I mentioned that I always have to watch the printer during the 9-point mesh bed level, because there is always melted filament that sticks to the bed and I have to hurriedly wipe it off before the actual print occurs. The default starting g-code is this:
M115 U3.0.9 ; 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 pritn area
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
On the thread someone suggested that I change the starting g-code so it didn't warm up the nozzle until *after* the mesh bed leveling. The code they suggested is this:
M115 U3.0.8 ; tell printer latest fw version
M83 ; extruder relative mode
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
G1 Y-3.0 X0 Z10.0 F1000.0 ; move outside the print area and above the bed to heat
M104 S[first_layer_temperature] ; set extruder temp
M109 S[first_layer_temperature] ; wait for extruder temp
G1 E3.0 F1000.0 ; begin extrusion
G1 X20.0 Z0.2 E3.0 F1000.0 ; move down to bed while extruding
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
I tried it out and it works quite well, and I've started using it on all my prints. There is one strange thing though: during the nozzle heat-up stage right before it does the intro line, the y-axis jerks and pulls it to Y0.0 line instead of the Y-3.0 where it normally is just below the printing area. So then the intro line is at Y0.0 right on the edge of the printing area. It's not a huge deal, since I've never had a print that needed the full 200mm in the y-direction, but it really bugs me because I can't think of a reason why it would do that? Can I just correct for it by adding
G1 Y-3.0
right before the extrusion step? But why would it be moving to Y0.0 in the first place?
Derek
Re: Strange behavior when changing start g-code
Well personally, I do the 9-point cal with the nozzle at 170:
; Prefix G-Code sequence START
T<EXT+0>
M201 X1500 Y1500 E900 ; set default acceleration
G21 ; set units to millimeters
G90 ; use absolute coordinates
M83 ; use relative distances for extrusion
M140 S<BED> ; Heat the bed + 5 degrees for Mk2
M104 S170
M190 S<BED> ; Heat the bed + 5 degrees for Mk2 and wait
M109 S170
G28 W
G80
M109 S<TEMP>
G92 E0.0
G1 Y-3 Z0.250 F7200.000
; Purge line here
G92 E0.0
; Prefix G-Code sequence End
Note that the temp variables are KISS specific. You should extrude whatever purge line you require.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Strange behavior when changing start g-code
I do the same! (but with slic3r) 9-point cal at 170. It's not good to do it cold, because if the nozzle is not perfectly clean, the plastic will hit and ruin the bed. Doing it at full temperature leaves oozing around the bed instead. 170 seems a good temperature for both PLA and PETG. The overall start procedure is somewhat slower tho
Re: Strange behavior when changing start g-code
The overall start procedure is somewhat slower tho
Not sure that is true. If it is, then there really is not much difference. When I have used Slic3r, the default start GCode first warms the bed, then the warms the extruder. hence a longer wait. My start GCode warms both at the same time. Things may have changed; I don't like Slic3r, I just don't seem to be able to work with it as well as some other users do.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…