Thin gap between outer wall and inner wall, only on small circular insets but not on the perimeter of the print...

[DeanSimmons 0]

I have a feeling that one of our bright minds will be able to handle this topic. The Solution is out there! Making an inner wall inset, something that advances the inner walls into the outer layers would be perfect!

 

Currently getting around this by setting my inner wall flow to 20% higher than all of my other values. It's only really suitable for having one inner wall, (and one outer wall. More inner walls would create too much squished material,) but with a 0.5mm nozzle, I really only need two passes with a nozzle to create sufficiently thick walls, and if I need more strength, I use "extra infill wall count" (1-2) plus "connect infill lines" to make my walls "thicker" using the infill to create extra "walls".

😊🌎🌟

Edited January 11, 2022 by DeanSimmons
Background information to help others find a workaround until a workaround is made. ❤️

[esopalumpa 8]

On 1/11/2022 at 7:06 AM, DeanSimmons said:

I have a feeling that one of our bright minds will be able to handle this topic.

I’m pessimistic about this. This is a long lasting problem and until now, I haven’t seen any effort to fix it.

[GregValiant 1,251]

I have seen this problem but it has been a rare occurrence (and hasn't happened lately).  I chalked it up to the material I was printing with but I have no idea if that was true, or if it was something Cura was doing to cause it, or my printer was just having a bad day.

 

This same issue has been commented on here, Github and over on Reddit.  I'm sure the developers have seen it discussed.  I know I can't duplicate it on purpose (and I have tried) and if the Cura team can't duplicate it then it's near impossible to figure out where in the code there might be a problem.

 

I can do a close analysis of a gcode file that has the problem.  If you would post a gcode file and a photo or screen shot showing where on the model the problem is occurring - I have some tricks to check things like the distance between the extrusions and the amount of flow of those extrusions.  If it is a small model and has a single hole in it that would be best.  I would bother to throw some filament at it to see if I can duplicate the issue.

[Simonlebucheron 0]

Hi, I finally get some time to document my experience with this wall gap issue.

I have the same issue with Cura (5.2.1). After many test, method of  @DeanSimmons work for me (almost): I have set my wall flow (not just the inner wall) to about 15% higher than all of my other values. This is the only way to get the right extrusion flow and no gaps between walls. I have added the parameter value in the print settings material manager for more convenience. Apart from the aesthetics issue, this is really a problematic issue when the flow is set low (that is my case) my prints suffer from sever wall adhesion and were very weak.

 

For a more exhaustive explanation of what I did to observe this issue:

• I was trying to suppress the gap between the walls after I calibrated the flow with a brand new spool type, and I found this thread.
• Estep is well calibrated, and my flow is calibrated for each material (using the method of the one perimeter cube).
• As a quick illustration I have used this euro calibration shape (and the associated parameters) and I can now assume that cura preview is a good indicator of reality for this test (It is what I experienced with about 30 serial prints on this test)

As reference the calibrated general flow is set at 91% for this material (I know, this is low):

Observation: with top view we can see gaps between walls, as well after printing.

 

When we adjust the wall flow to 105%:

Observation: no more gaps between walls and I can that print looks good now.

 

I found some of the tests I made few weeks ago, here are two examples:

• First example, general flow adjustment only

As reference, 100% flow (3 walls print):

Observation: squishy top layer, over-extrusion, some gaps in walls (reminder, calibrated flow is 91%).

 

First print illustration with flow adjusted to 91%, wall flow identical (calculated by cura):

Observation: gaps between walls but clean top layer

 

And the second print with the flow adjusted to 103%, wall flow identical (calculated by cura):

Observation: no gaps, correct wall width but squishy top layer (over-extrusion)

 

Second example, previous test exaggerated with 5 walls and adjusting the wall flow .

NotesSame material type, same origin and age but different color, sorry for less visible details (look at my observation notes). The test is reproducible.

As reference, 100% flow:

Observation: squishy top-layer, over-extrusion, (reminder, calibrated flow is 91%).

 

Flow 91%, Inner wall flow 96%

Observation: multiple gaps between walls, top layer seams acceptable.

 

Flow 91%, Inner wall flow 115%

Observation: no gaps between walls, top layer has the same quality as previous: not perfect but not worst.

 

Final remark: with a more meticulous inspection, there were small gaps between walls for the last experiment, that why my final conclusion was to adjust the outer and inner wall flow with the Wall Flow parameter (about +15%) to compensate the gaps between walls.

 

 

Another story, hidden flow parameter bug ?

I have also noticed something bad during my tests but I cannot reproduce it, I am ashamed. I saw two different previews (obviously flow related) with same parameters. To do so, I think I adjusted the outer and inner wall flow, right click to retrieve the material value for flow and generate a preview. Then I manually write the same number for the wall flow, re-generate a preview and it looks different, we could see the difference on the wall width. Maybe a parameter is calculated by Cura that I am not aware of, which change the wall flow... and so it could be a bug and/or the source of our initial problem, that is why I am telling you this story. Since I cannot reproduce it, this is just... "a story" so forgive me to suspect this great slicer that is Cura.

 

Cheers !

2023-03-02_18h44_flowtest_APLAECOO_1g_0h10.3mf

[GregValiant 1,251]

If you do a search around here you will find an excellent rant of mine regarding "single wall calibration cubes".  It boils down to this:

 

When you calibrate to a single wall cube, your printer will make excellent single wall cubes.

 

How often do you print single wall cubes that need a perfect wall thickness?  Because other than that specific condition...everything else you print will be under-extruded.