My CR-10 prints are coming out very rough only 2/3 of the way through

[hekg 0]

I'm using esun Petg on a CR-10 and yesterday I printed a 15 hour long job for a small flower pot but strangely it appears as if the first 1/3 printed ok, then the 2/3 printed super rough and the last 1/3 printed ok again.   See attached pic.

My settings in Cura are the default for this printer and for the petg I have it set at 240 nozzle, 85 printbed, layer height 0.2, speed is at 40, retraction distance 5 and retraction speed at 40.

I'm fairly new to 3d printing and I've been using these same settings for a few weeks with no problems but this is a new problem with all my prints lately. Any suggestions will be greatly appreciated , thanks!

 

 

[RoboDLC 0]

I just had this happen and it took three days to figure it out.  I use both CURA and Simplify3D, and my models had the exact same problem as you describe, in both slicers.

What I discovered is that in places where there are a lot of retracts due to crossing open space to the next landing, if you have retraction distance set too high, your get what I call a "starve-gush" cycle that makes it look like your printer is alternating a weak extrude and then an over-extrude.

Try reducing your extraction distance.  I went from 5.5mm to 3mm and the issue went away.  I too was using a 40mm/s retract rate.  I am using a Delta printer, but the same dynamic might still be in play.

 

DLC

Edited September 5 by RoboDLC
further elucidation

[hekg 0]

1. Thanks for the tip Robo.  I'll give that a shot ??