I have been tinkering with Cura and couldn’t help but notice that although Cura has boxes to enter initial layer temperature for both the nozzle (material) and the bed, it doesn’t seem to actually use them.
Evaluating my pre-print Gcode settings vs Cura’s variables, I thought that perhaps I needed to add _layer_0 after my variables to accomplish this, but it doesn’t seem to like it very much.
I tinkered with it a bit further last night so its possible that I have it resolved now, but can someone please look at this and tell me what, if anything, I am doing wrong?
I went ahead and pulled _layer_0 from the print bed temperature because it kept trying to set it to 250 degrees instead of the variable I assigned.
The reason I would like to do this is because I am having issue with this particular filament sticking to the bed, so I want to start off at a higher temperature then tone it down to where it prints nicest at.
PS shouldn’t initial layer settings also apply to skirts, brims and rafts?
;M104=print temp, M140 = bed temp, 109 = print temp wait, 190 = bed temp wait
M104 S{material_print_temperature_layer_0} ;Start heating bed
M140 S{material_bed_temperature} ;Start heating extruder
G28 ;home
G90 ;absolute positioning
G1 X-10 Y-10 F3000
G1 Z0 F1800
M190 S{material_bed_temperature} ;Wait for bed to reach temp before proceeding
M109 S{material_print_temperature_layer_0} ;Wait for extruder to reach temp before proceeding
G92 E0
G1 E20 F200
G92 E0
Before my prints start, it craps out a string with tends to loop and then hooks on the side of the print plate before printing. Unraveled its probably about 6" long or so.
More curious than anything… I’d love to understand more of the things you guys do to end up with better results. Not just copy paste but understand
G92 sets an axis to a position (E, extruder, is the 4th axis).
G92 E-1 ; Tell the machine the extruder axis is at position -1mm
G1 E0 F200 ; Tell the machine to extrude to E axis 0mm at 200mm/min feedrate
This extrudes 1mm of filament, and leaves the E axis at position 0, with 1 fewer line than you’ll typically see.
G92 E0 ; Zero out the E axis
G1 E1 F200 ; Move axis off zero 1 mm
G92 E0 ; Zero it out again
Your setting of G1 E20 feeds out 20mm of filament, a huge amount.
Leaving the E axis at 0 is essential in the prep code, as the first line of the print will read something like this:
G1 F1080 X123.241 Y159.373 E0.01787
If the E axis is left at a position of 20mm from the start gcode, and then goes to 0.01787mm, it will in effect retract 19.98 of filament, instead of the desired result of extruding a small amount.
Yeah I just kind of hobbled together the Gcode and the machine variables from various posts on the internet, kind of combined a few things I had read.
That makes sense and I will adjust to a lesser feed similar to what you have shown.
However, wouldn’t a longer pre-extrusion before printing improve the flow rate once it gets to the print bed and actually to work, or is that not really a thing? I would have assumed that it should be gotten nice and flowing before startin the job.
In Cura I have a minimum skirt length set to ensure it will finish priming. In Simplify3D I just make sure there’s more than 2 skirts for small parts, since there’s no minimum length setting.
You run the risk of priming at the home position and having some drip out of the nozzle before arriving at the start of the skirt.
I retract 2mm at the end of the print, and prime 1 at the start of the next print making up the extra prime in the skirt, other people do other things - it’s easy to change and completely a matter of personal opinion. I recall sdj and atom do a combination of a priming line at the edge of the print area and a full prime at the start.
Single skirt usually does the job, 2 always does, but I do a 3 layer skirt because I find it’s easiest to remove. Doesn’t really take that much more time or filament. Most of the stuff I print is 150mm at the largest. If I was to print anything really big I might reduce it.
That’s on Luban though. Haven’t really gotten into Cura much. Have been doing a lot of cnc and laser lately. I know I need to make the switch but the stuff I had been printing wasn’t critical and Luban worked fine.
