"Strange Pattern" in first layer

[mranton 3]

Hi!

 

I'm aware that the title isn't very clear - but I'm not sure how to describe it - hence the "strange" 🙂

 

As you can see on the photo, my first layer shows these patterns. There is no problem with layer adhesion or whatsoever - the layer comes out flat and shiny, but with these patterns.

Has anyone seen this before? Any idea how to fix this?

 

Printed on an U2+ with U Silver metallic PLA. Standard settings for the material. 

 

thanks,

Anton

[Framar 38]

Hello, 

 

Hard to say from a picture... I'm assuming the printer print these lines from one edge of the part to the other. If so, then, it looks like something was on the build plate when the first layer was printed and that first layer was not squish enought against the build plate.

 

I might be completly wrong.

[geert_2 558]

You would need to sit next to the printer and keep watching. My guess is that the bed is not perfectly clean, and/or the glue (if you use glue for bonding) is not spread equally. So the printed sausage does not stick perfectly.

 

In such cases, I have seen these printed lines lifting a little bit on the outer edge. And then, on the next pass of the nozzle in the opposite direction, they would be melted again and be pushed against the bed again. If the bed-adhesion is not identical everywhere, this could cause similar irregular patterns.

 

Filament with silver or glossy particles makes this much more visible, since the orientation of the filler particles changes, and thus their reflection. Mostly the fillers are flakes, little mirrors.

 

Printing thinner first layer lines might help. But then your bed leveling and bed flatness need to be very good.

 

You can see this effect to some degree in these photos too:

 

 

 

[mranton 3]

Thanks guys! 
I am using glue stick and usually I distribute it evenly, but I’ll pay especially attention to it next time I print. There was for sure nothing on the build plate, but the explanation that the first layer was “pushed down “ by the second makes sense - also seing that there is a diagonal pattern. 
I’ll check it out. I’m using the U2+ since 3 years - never saw that pattern before.

thanks again!

[Framar 38]

I ran into the same issue last week.

I my case I noticed that it was caused by some drooling during nozzle move when printing the first layer.