How do you get good first layer height consistency?
I've been working on a few prints lately that require fine-tuning the first layer, and therefore good consistency from print to print to get the same results. I'm finding that I dial in the live Z adjust to get the perfect .2mm first layer dictated by my slicer, but then the very next print will suddenly have a .26mm first layer with bad under-extrusion. Is there any way to fix this besides waiting for the new temp-compensated probe in the 2.5 upgrade kit? Does any particular workflow work for consistent first layer height, like "start the print cold and make sure your slicer doesn't pre-heat"?
Re: How do you get good first layer height consistency?
Can I assume the silence means nobody ever gets good first layer consistency?
Re: How do you get good first layer height consistency?
Can I assume the silence means nobody ever gets good first layer consistency?
I get perfectly good consistency.
The common solution to this is to make sure the PINDA probe is at a higher Z value during the warm up pre calibration.
Most people have modified their "before print gcode" to only heat to a lower temp (to prevent drips) before the calibration, ands to do the warm up with a higher Z value. Something like this:
M115 U3.0.12 ; tell printer latest fw version
G21 ; set units to millimeters
G90 ; use absolute coordinates
M83 ; extruder relative mode
M104 S170; Extruder to 170
M140 S[first_layer_bed_temperature] ; set bed temp
G28 W ; home all without mesh bed level
G1 X0 Y0 Z125; home X axis Lift to 125
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S170 ; wait for extruder temp to hit 170
M104 S[first_layer_temperature] ; set extruder temp
G80 ; mesh bed leveling while rising in temp
G1 Y-3.0 F1000.0 ; go outside printing area
M109 S[first_layer_temperature] ; wait for extruder temp if needed
G92 E0 ; reset extrusion distance
G1 X100.0 E9.0 F1000.0 ; intro line
G1 X200.0 E12.5 F1000.0 ; intro line
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 or loss. If you solve your problem, please post the solution…
Re: How do you get good first layer height consistency?
What is the intended result of that sequence - to do the mesh leveling with the probe not as hot as it would be sitting low over the warm bed?
Assuming it was temperature drift related, I adjusted the Z height for consistently running the print start (and mesh leveling) at full bed temp with the probe warmed up. I figured that was the only way to assume the probe would be at a consistent temperature, since doing it cold-cold would have only behaved consistently for the first print of the day.
I guess I'll try that start sequence though.
Re: How do you get good first layer height consistency?
Okay - comparing to my current code in Cura:
G21 ; set units to millimeters
G90 ; use absolute positioning
M82 ; absolute extrusion mode
M104 S{material_print_temperature} ; set extruder temp
M140 S{material_bed_temperature} ; set bed temp
M190 S{material_bed_temperature} ; wait for bed temp
M109 S{material_print_temperature} ; wait for extruder temp
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
G92 E0.0 ; reset extruder distance position
G1 Y-3.0 F1000.0 ; go outside print area
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E21.5 F1000.0 ; intro line
G92 E0.0 ; reset extruder distance position
Most of it just looks like re-sequencing. But my current code uses M82 absolute extruder mode, rather than M83 relative mode. Is that something I shouldn't change when copying yours?
Re: How do you get good first layer height consistency?
So I think that code must be for Slic3r, and the cura syntax is a little different. After some digging, I finally settled on this, which does everything you mentioned. Hopefully it'll sort out my print-to-print variability.
; New code for Cura
G21 ; set units to millimeters
G90 ; use absolute coordinates
M82 ; absolute extrusion mode
M104 S170; Extruder to 170
G28 W ; home all without mesh bed level
G1 X0 Y0 Z100; home X axis Lift to 100
M140 S{material_bed_temperature_layer_0} ; set bed temp
M190 S{material_bed_temperature_layer_0} ; wait for bed temp
G80 ; mesh bed leveling while extruder is rising to 170 (though it's probably there by now)
M104 S{material_print_temperature_layer_0} ; set extruder temp
G92 E0.0 ; reset extruder distance position
G1 Y-3.0 F1000.0 ; go outside print area
M109 S{material_print_temperature_layer_0} ; wait for extruder temp
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E21.5 F1000.0 ; intro line
G92 E0.0 ; reset extruder distance position