PETG extrusion issues

Hello,

I'm using PETG from eSun to print multiple parts on my reprap printer. For some reason, the flow of media from the extruder appears "rough" or "intermittent" in the middle of the print bed when I print a large batch of parts.

See the attached photo. If anyone has thoughts as to the cause (and a possible solution), this would be a significant help.

Thanks!
--Donn

my guess is a slight bow in the bed causing the hotend to be coloser to the heatbed.

Appreciate the response. (And, this makes sense.)

It appears that the print is succeeding--I'd been concerned that if may fail early on--so, I guess it's just something that I'll live with for the time being.

Thanks!

I was fighting similar issues with nylon.
The bed was perfect enough but still there were those lines that look like they had bubbles in them and totally rough surface.
All plastics that do a lot of expanding and shrinking need perfectly calibrated settings!
But the most important factor for me was not to trust the automatic line width settings!
With badly shrinking plastic you need a perfect bond between layers and lines on the same layer.
So manually setting the extrusion width to something that is close to the limit fixed it for me.
I use a 0.3mm nozzle most of the time and set the extrusion to 0.42mm, everthing below or automatic and the nylon messes up.

PETG does not shrink much, there is less warping than I had with PLA.

Like it had been mentioned, I put my money on to small z-height ( caused by bed irregularity )
-Olaf