Strange under extrusion please help

Thank you in advance. Using an Ender 3 with octoprint and Cura 3.6.0. Not sure if I have a hardware or software issue, but I get under extrusion at holes or cutouts as you can see by the photo. Using PLA with a 0.5mm nozzle and EZR extruder add on. No slipping of the bowden tube I can detect. As you can see from the photo it ALWAYS occurs at a hole or slot???

Does it happen at the same Z level if printing another narrower object? If yes then Z system makes a sudden jump at that level.

Thank you, I’ll have to look out for that. Just noticed it makes the part very weak around holes and cut outs.

@deruida for strong parts I recommend using PETG and keep PLA for art printing

Thank you for the tip. I am new to the 3d printing world. And I guess you can teach an old engineer new tricks!

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@deruida The picture just doesn’t have enough resolution for me to tell what’s really happening. It isn’t obvious that it’s actually under-extrusion. You could have under- or over-retraction, for example, or mechanical slop (loose belts, insufficient preload on wheels, etc). You could try to reduce Y acceleration and/or Y jerk settings and see if that changes it at all; if it’s a difference in bed movement that can make a difference. I run much lower Y accel/jerk than X on my “bed flinger” printer.

I have used PETG for some very durable parts, though it tends to be more “stringy”. I’ve used esun’s PLA+/PLApro when I’m looking for a middle ground that is tougher than PLA but less stringy than PETG, including some cases.

PETG does make troubles with 0.4 nozzle. Almost none with 0.6 nozzle and none at all wit 0.8 nozzle, so mechanical parts without art I do with 0.8.
The 700mm Dragon in my album is 0.4 nozzle, the woman torso too.

My Albums

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Actually for better vision of the problem indeed to make a high resolution album of the printer and its corners, especially that no one of us has experience with all. Please see QuadRap Detailing in my album as an example.