Very uneven brim printing

[IanHamilton 0]

Printing from Ender-3, Cura 4.6.1, octoprint.

The brim is very uneven but reproducible over two different prints. At the same stage of printing the very line of the brim, the extrusion fades away to almost nothing and is really just a smear on the bed. Then the feeder suddenly starts over feeding creating a lumpy deposit. Each line of the brim is of course a little bit shorter so the discontinuity appears as a slanting line. See the photo.

The print itself seems fine.

Printing with a skirt is fine.

Comments would be appreciated.

 

[Guest maht]

Check if your bed is level. In the top area the nozzle is squeezed right up against the bed, and therefore extruding less, which creates this effect.

[IanHamilton 0]

I leveled it right before this print. And also printing with a skirt does not exhibit the problem

Also here is a photo of the brim AND part of the first layer of the print

 

I though at first that the problem was that the extruder was not feeding evenly, so I analyzed the GCODE

and munged it around to plot the distance of each line and the amount of extrusion.

It looks pretty good, so I am at a loss

 

Edited June 23, 2020 by IanHamilton
Additional Information