So I'm having a bit of a strange issue where I'm getting gaps between perimeter walls, but only on part of the print. Even more strangely, it doesn't happen with every print, though it will happen consistently on the same model if I print it more than once.

I know the go-to answer for an issue like this is "You're under-extruding. Fix your e-steps or increase your extrusion multiplier", however I'm not sure that's the only issue at play here. I did try increasing my extrusion multiplier (tried both 1.05 and 1.10), and while the issue did improve, it didn't fully solve it. The print shown below was printed with an extrusion multiplier of 1.00.

Also worth noting is that there is a bulge in the side of the print toward the bottom, but I'm not sure if it's related to the perimeter wall gaps issue. I have no idea what would cause that.

Basic Info

Printer: Ender 3 Pro
Filament: Hatchbox PLA ("gray blue")
Slicer Software: Slic3r

Slicer Settings

Note: I am only adding the settings I believe are relevant to the question. If you would like to see a setting not shown here, please let me know and I'll add it.

  • Print temperature: 200 °C
  • Bed temperature: 50 °C
  • Installed nozzle is 0.6 mm.

Print speed settings

Print layer settings

Printer extruder settings

Print Images

This first picture is to show the orientation of the print on the print bed: Print orientation

Print closeup


2 Answers 2


You are using a larger than "standard 0.4 mm" nozzle. Large diameter nozzles cause flow volume to increase when the extruder etrusion speed is kept the same as for the standard nozzle which can cause extruding problems like underextruding.

The nozzle diameter increase appears marginal (as in "it is just an extra 0.2 mm in diameter", but actaully the nozzle increases 50 % in diameter), but has significant effects on the volume flow of the extrusion.

As seen from the table below, when increasing the nozzle diameter for the same printing speed, the volume flow increases from 1.26 mm³/s to 4.24 mm³/s which is a 337.5 % increase of the flow for the selected layer height (0.3 mm).

enter image description here

This increased flow must be created by your extruder/nozzle assembly and might fall out of the range it can produce for the current setting. Generally this requires you to increase the printing temperature or decrease the printing speed.

  • 1
    $\begingroup$ Thank you, I hadn't even considered that the flow volume might be an issue. I finally calibrated my e-steps last night. Doing that and printing a little bit slower seems to have solved the issue. $\endgroup$
    – Gogeta70
    Sep 2, 2023 at 1:41

I had this in 3 new Ender 3 pro's. It was the nozzle was too small. I checked the output of the nozzles by extruding and measuring the filament after it hardened right at the nozzle. A good nozzle will measure exactly to the size.

  • 3
    $\begingroup$ The amount of material the extruder is pushing, not the nozzle size, determines the width of extrusions. $\endgroup$ Sep 1, 2023 at 0:59

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