First layer lines misaligned

[Jpileggi 0]

What would cause the first layer to look like this? I am printing on clear glass. The lines should be straight horizontally, yet portions of the lines are offset. This profile printed perfectly previously as can be seen in the right hand piece in the second picture. Just prior to printing, I washed the glass, wiped down with isopropyl alcohol, and then sprayed lightly with hair spray. The piece feels smooth; just looks horrible. Thanks.

[GregValiant 1,318]

This isn't helpful, but I've gotten that pattern occasionally and never figured out why it occurred.  My thought was that clean or not, it's related to the build surface rather than anything else.  You can see the pattern from above before the second layer goes on.  The pattern never appears on layers above the first layer either.  It's also too regular to be related to the filament (moisture) or oddities of the extruder.

The one thing in common here is that I print on glass and use hair spray for bed adhesion.  Go figure.

[Jpileggi 0]

Thanks Greg. I wonder if the nozzle needs replacing.

[GregValiant 1,318]

It could be.  A nozzle's ID will wear and become over-sized over time (some material are worse than others) it shouldn't leave a pattern that comes and goes like that.

Regarding nozzles, I have noticed that some nozzles produce a "roostertail" effect at higher speeds and that causes material to collect on the outside of the nozzle.  After it builds up to critical mass it comes off in droplets on the model and is highly annoying.  So not all nozzles are created equal.

 

Back to the pattern, for right now I'm sticking with "It's a bed thing".  Nothing else I've thought of really fits what we see.

Edited November 5, 2023 by GregValiant

[Jpileggi 0]

So it's not the bed. I reprinted the same gcode file that produced the good resulting part in the pic above, and it printed fine. When I reslice that part file with my current profile, I get the mess shown above. I may have modified the profile from good part to bad part, but I don't know what changes may have been made. Am I correct in assuming there is no way to identify all the parameters of the profile simply from the gcode file?

[Jpileggi 0]

Here's the pic of the new part sliced with a different profile. Beautiful first layer. Something was ailing with that other profile.