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I've had an Ender 5 Plus for a few weeks now. It's printing great and I've got my tuning pretty good at the moment. I've noticed some horizontal inconsistencies matching feature/geometry changes. It seems to be associated with maybe layer time(?) I only have a picture from two models, but the problem will appear in other places on different models, always matching some change in the layers.

The problem is consistent all around the model and changes position with different prints, so I know it's not a mechanical problem. Say I printed a 2x2 cm tower 20 cm tall, it will not have any of these imperfections because every layer is identical.

I highly suspect the layer time/temperature change, but I don't know how to fix this, I'm a bit stumped. They both were printed at 200 °C and I'm trying a new one at 210 °C (best temperature with the spool I have) and it has the same problem. All three models are from the same spool of PLA.

Also, I use Cura with mostly default settings for the Ender 5+.

Here are the pictures :

I tried to highlight the idea, but every line matches with some change in the model Model 1

On the benchy it's harder to see, but the hull line match with the solid floor of the model, and the top ones match with the top window sill starting.

Benchy

0scar
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GmodCake
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3 Answers3

1

This is varying underextrusion due to loss of material to oozing in the interior of the model.

When printing the infill pattern, the nozzle doesn't follow a single continuous extrusion path, but moves from the end of one path to the beginning of the next, and under Cura defaults, does this without retracting the filament. This causes unpredictable amounts to ooze out during travel from one to the next, thereby desynchronizing the planned/intended amount of material extruded so far and the actual amount. This means, when the next outer-wall extrusion starts, there's an unpredictable deficiency between the amount of material at the nozzle to extrude, and the amount the slicer intended to extrude. The result is what you're seeing.

To fix it, you need to eliminate oozing, not just outside the model where it appears as visible stringing, but inside too. Either disable "Combing" entirely in Cura, or set "Max Comb Distance With No Retract" to something very low (0.8 mm or less). Also set "Minimum Extrusion Distance Window" to 0 to ensure Cura doesn't skip retractions for other reasons.

You may also want to play with extrusion length and speed. Too short or too long can be bad; 5-7 mm is the reasonable range for PLA with a bowden. Higher speed generally helps too; the printer should be able to handle 50 mm/s or faster.

R.. GitHub STOP HELPING ICE
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0

If this matches the horizontal planes - like "solid floor" than I would advice to check overlap settings. My suspicion is slight overextrusion, which might be the reason of many small horizontal differences. Using 3 mm filament I often suffer of similar inconsistencies, until I find proper flowrate to avoid overextrusion. Adding first to second, the solid plane will push walls more to sides.

Do you print "Infill Before Walls" (Cura setting)? You may try to disable this checkbox and observe if the result persisted. Also you may enable "Outer Before Inner Walls" - to ensure, that outer wall is printed first with least interference (though some other issues may appear after travel, layer change, etc.).

  • So try print from outside to inside (outer walls > inner walls > infill).
  • Then try to reduce "Flow" until you see no overextrusion (or even small gaps in the surface).
  • Finally revert these settings (infill > inner > outer) and check again.
0scar
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octopus8
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The issue with the "hull line" is known. It depends on the fact that the material shrinks after extrusion and faster layers give less time to the previous layer to shrink, so they appear continuous, while slower layers take more time, so the previous layer has more time to shrink and there will be a visible change in the outer dimensions.

So, larger layers are the slower ones. You can increase the temperature a bit, so that it will take more time to cool down to the shrinkage temperatures, you can print faster, you can increase chamber temperature to have more time before shrinkage, or you can cool more the part so that no matter the current layer time, the previous one will always be already shrunk.

In the Polymaker Discord server there is a channel about the "hull line". You can find an invitation to the server and check there.

FarO
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