Uneven first layer on UMS3 Prints

[skjbTHI 0]

Hello,

 

I've noticed on a number of prints from our UMS3 that the first layer seems to be a bit uneven. When this happens on the corner of prints, I'm usually able to solve it with the typical anti-warping tips and tricks (adding chamfers to the 3D file, putting glue on the build plate, etc). But I've noticed more recently that it seems to be happening away from the print edges in some cases. In the attached photos, I think it's most clear in the blue print - tough to get a good image of this with the lighting in my office, but even in the gray prints (paused after first layer went down) I can see a few features which look to be uneven, not flush with the build plate. I've hypothesized that it could be due to uneven layers of glue on the build plate, but I have noticed this even after thoroughly cleaning the pate. For typical prints this isn't an issue—the blue part functioned fine—but there are other times when it seems this uneven-ness propagates through subsequent layers, or else times when we need the smooth bottom layer for the functionality of the print.

 

Since I have experienced significant warping issues when printing PLA on this UMS3, I typically make the following alterations to my initial layers:
Increase initial layer height (by roughly 20%)

Increase initial layer flow (Cura default is 120% for initial layer, I up to 130%)

Initial layer temp +10 degrees from normal print temp

Initial layer build plate temp +5 degrees from normal

Initial fan speed of 0, regular fan speed at 0.65mm

Initial layer print speed roughly 25% normal print speed

Brim (with brim size increasing with print size)

 

 

These alterations have positively affected the warping isseus, but could these or other factors affect the "flush"-ness of the initial layer with the bed? 

  

Edited March 31, 2021 by skjbTHI