3DPrinting

Print vertically or at a 30-45 degree angle

Try YES next time :p

Set your slicer to only use one wall for the top layer. Edit: also, calibrate your extrusion. This looks like slight underextrusion to me.

Looks like you answered your own question. :)

Yes you can:

• enable Arachne in the slicer

• tune the pressure advance setting

This is a fairly common complaint with the output produced by any slicer using the Arachne perimeter generator, which includes Prusa and its derivatives by default now, and also Cura.

If you are using Prusa or a derivative you can switch back from the Arachne perimeter generator to Classic in your "Layer and Perimeters" tab. If you can't stomach not using Arachne for whatever reason, you could try messing with the "Perimeter Transitioning Threshold Angle" setting. There is some additional wordage on all of the above here. TL;DR: The Arachne generator attempts to build perimeters out of variable line widths and explicitly does not go back and fill in tiny voids like these with a separate operation. The point is that it's not supposed to have to, but as you can see it doesn't always work out that way.

As others have pointed out, doing an ironing pass on your top layer may help conceal this from an aesthetic standpoint but won't do anything for you structurally (i.e. for anyone running into this issue with a shape they hope to be watertight). The nuclear option would be to instruct the slicer to do an ironing pass on every layer which may help your print look boss at the end of things but will certainly also take forever.

Does your slicer have Arachne slicing mode? It will use variable extrusion width which will help to prevent most of those gaps.

To me it looks like tuning your pressure advance might help.

https://ellis3dp.com/Print-Tuning-Guide/articles/pressure_linear_advance/introduction.html

other than what is already suggested, could be the top layer pattern you are using. try some different ones

Which slicer are you using? You can try setting ironing to on and the wall generator to arachne

@ExtremeDullard

There is less material than needed all over the place, look at the not bonded perimeter lines on the top corner.

Measured the real filament diameter before printing and corrected the slicer settings to the measured diameter?

Are the extruder steps calibrated?

If iam to lazy to reslice, i would increase feedrate to around 106% and look at the following layers if the gaps are closed mid print.

This can be seen at layer 2 and corrected while printing

Im only familiar with Cura. Cura has wall settings I think you are looking for to fix your problem. I had similar issues with a print. Used settings like wall transition length, wall distribution count, wall transitioning threshold angle, wall transitioning filter margin, and minimum wall line width. I was able to fill in tight corners, just took a little while dialing in the settings.

Write your gcode by hand and you can do curves thus ensuring lines won't meet. I last wrote gcode by hand in the 1990s, and I'm pretty sure industry stopped hand gcode around 2000 (before 3d printing), but the language isn't difficult and so you can do it.