Strange first layer artifacts
I am printing a case for and electronic device using and MK3s. The case is printed face down, so the first layer needs to be perfect because it is the most visible one.
My initial few prints turned out good with fairly smooth layer lines but then I started to get strange artifacts in the lower left region of the print. Nothing has changed in the .gcode and the same problem happens on 2 different printers (both MK3s). The problem is the same with different filament brands as well as using PLA or PETG.
I am using the Prusa steel sheet and have cleaned it thoroughly with IPA, soap and even acetone, it doesn't seem to make any difference.
The current images show the problem in the lower left of the case. If I rotate the model by 180 degrees, the problem appears in the upper right, so it does not seem to be related to the print surface.
I have tried slower speeds, higher/lower bed temp, xyz calibration, different filaments,Z-layer adjustments etc. Once I a while, a print will turn out good but 90% of them will show those strange artifact that are almost identical each time.
Does anybody have an idea what could cause this issue? I am at my wits' end.
RE: Strange first layer artifacts
Clean bed with dish soap only, more is not needed.
Check if your first layer is correct, and make picture for us to see.(stop your print and look at first layer if it is correct).
You could have a partially clogged nozzle, do a few cold pulls, with high temperature filament.
RE: Strange first layer artifacts
Thank you for your response. The first layer looks ok (see picture) and I have replaced the nozzles a couple times (E3d .40) it made no difference. I rotated the orientation of the print by 180 and now, instead of having problems in the left area, they occur in the right area.
In addition, the issue is not consistent. After I posted the topic, I was able to get a perfect print, with no changes to settings, but the next one was flawed again. What I don't understand is that if it is a problem with some of the settings or first layer Z-height, why am I able to produce a perfect print once in a while without changing anything? And why is it happening on both printers? I also considered a possible issue with the PEI sheet but it looks fine, and it would not explain why rotating the print will shift the problem areas to the opposite side.
These sample are printed with PETG based on Prusa's Generic profile but I had the same issues with PLA (that's why I switched to PETG, hoping it would improve)
First layer
Flawed print on the left, perfect print on right, same settings, printed one after the other
RE: Strange first layer artifacts
The pinda detects the metal print surface at different distances depending on how warm it is. This can lead to inconsistent first layers when printing prints one after another as the second and subsequent prints the probe is warmer. Especially if you adjusted the z initially with a cold bed.
Its why some use a modified start up gcode sequence that preheats both the bed and the pinda to get a more consistent first layer.
It may be worth you trying it. Details on how to modify your start gcode can be found at Bob's website here http://projects.ttlexceeded.com/3dprinting_prusaslicer_gcode.html
RE: Strange first layer artifacts
Another point... looking at the pic on the left, it looks like there is some under-extrusion. The advice to lower Live-Z applies, but it is interesting that you sometimes get good prints. Th 1st layer does look good otherwise. I'd try printing again and dialing speed back 50% using the front knob for the 1st layer. If that cleans it up, just reduce your PETG 1st layer speeds or Max volumetric speed slightly for that particular filament.
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RE: Strange first layer artifacts
@neophyl
Thanks for your reply. Interesting, I didn't know that the pinda works based on temperature. I am not sure if this applies to my case though because I let the print cool down completely and then clean the surface and apply a rinse of soap and water. There is usually at least 30min to an hour between prints. I have been using 15% for first layer speed but will try and dial it down some more.
Just started a print with Bob's gcode. I definitely eliminates the oozing during mesh leveling, I can tell that already.
RE: Strange first layer artifacts
@bobstro
Thanks for your reply. I agree that it looks like under-extrusion because seem to be tiny holes and gaps in the flawed areas of the print. I have experimented with different z-levels and the current one (initially) produced the best results. I have been using 15% on first layer but will try to dial it down and use the modified gcode.
I took a picture under the microscope, it shows the flaws very clearly. I just don't understand how this can happen inconsistently without any changes in the settings or setup.
RE: Strange first layer artifacts
Let printer warm up, bed and nozzle to print temperature, wait 5 minutes or longer if it is cold.
Then do z-layer calibration wen it' s warm.
Then every print you start, let bed warm up for longer time, then start the print.
And adjust every print the live z if this is needed, adjust by looking at first lines of the print.
RE: Strange first layer artifacts
@marcog
If i look at the pictures with the letters, around the letters it looks like the first layer is not low enough.
Check if spring is of extruder is good adjusted, you could try make it a little harder.
RE: Strange first layer artifacts
In the printer use the 7x7 calibration in the settings.