5.3.0 closes small holes (5.2.2 did not)

[mennucc]

Application Version

5.3.0

Platform

Ubuntu

Printer

Creality Ender 3 Pro

Reproduction steps

I have a model called negative test with small slits, that can be used to calibrate the flow.

With Cura up to 5.2.2 , it is sliced correctly, as you see in this image

With Cura 5.3.0, the smaller slits are filled in, as you see here

I have set

• material: generic PLA
• printer : Ender 3 Pro
• settings : standard setting , with no changes

Actual results

The slits are filled in, so the model is printed incorrectly.

Expected results

The slits should not be filled in.

Checklist of files to include

• [ ] Log file
• [X] Project file

Additional information & file uploads

For your convenience, here is the STL of the model: negative_test.stl.zip .

And the project file cura_5.3.0_.3mf.zip

[GregValiant]

Thanks for the report and the files. Turn on "Print Thin Walls" and set the Minimum Feature Size to 0.05.

This looks like expected behavior but I'll leave the bug label on it In this case it would appear that "Print Thin Walls" should be "Print Thin Gaps". This is a well hidden phenomenon.

As an aside... To calibrate "Flow": Calibrate the E-steps and stop right there. Use a magnifying glass to inspect a top skin and tweak the Cura Flow settings as appropriate per what your eyeballs actually see. Nothing else is required or needed.

[mennucc]

I can confirm that those two settings enable a correct slicing.

As for the "flow" calibration. I could not print some print-in-place objects , such as kaleidocycle where there are very tiny gaps that must be empty ; my negative test was useful to set correct parameters.

[GregValiant]

I'm going to re-open this. I think it's something that isn't clear in Cura. Maybe adjusting a Tooltip or something similar would help as "Minimum Feature Size" and "Minimum Thin Wall Line Width" are hidden unless "Print Thin Walls" is enabled.

[UBaer21]

I just wondered about this ( Cura 5.6.0) as without "Print Thin Walls" enabled it seems the "Minimum Odd Wall Width" also determines the minimal gap/slit size which doesn't make sense. When printing with big nozzles (like .8) you may not want to print a .4 wall but you sure can print a .5 gap.