No hole in bottom surface when printing Spiralized

[Martinmutter 1]

Sooooo am I just gonna have to start using some other slicer or is there an actual solution to this BS?
I NEED that 41mm diameter hole. I don't have a decent drill for it and I do not feel like finding one when this has worked before.
Or do I have to go back to using an old cura installation for this model?

Also why do I get 

 

[Slashee_the_Cow 541]

If you could provide the .3mf file for the project that would greatly help as a couple of screenshots aren't much to go by. I created a quick mockup similar to yours and got a sort of similar problem:

Cura 5.4 inherited some slicing bugs from the engine it uses so I thought I'd check 5.3.1 but got the same problem. Sometimes the slicing bugs can be fixed by turning down Mesh Fixes > Maximum Resolution but that didn't seem to work for me.

 

Playing around with some settings I did get an interesting interpretation when I set the line width just right:

By setting Special Modes > Surface Mode to Surface, it did solve the stray lines, but then it won't print the bottom (although you could move it up and put another mesh with a hole the right size immediately below it).

Although I can't help but notice that it's printing multiple lines, which it's not supposed to do:

I'm thinking "maybe it has something to do with how I made the model" (in OpenSCAD, created two cylinders with a difference() and then use a third to make the hole), and I can see that it's definitely seeing the gap between the two cylinders, but I'm not sure if that's the actual problem.

 

But it does slice perfectly fine in 4.13.1:

 

So I wish I could narrow down a cause (or a solution), but it's obviously something in the code somewhere in the 5.x versions. Fortunately you can have different versions of Cura installed side-by-side without any problems whatsoever (which is why I have four installed at once for testing) so unless someone has better detective skills than me my answer is just to use 4.13.1 when you have a situation like this come up.

[Martinmutter 1]

Oh yea it's definitely a Cura 5.x issue... Was just hoping there might have been a setting that could workaround it. 

The issue is the hole in the bottom. It's a lampshade designed with a 41mm hole in the bottom.

It works fine on older versions. But hoped someone here might had come up with a solution. Or that Ultimaker themselves fixes it.
 

It even have a less smooth surface then the 4.x spiralized.... 

Looks. Meshy if you know what I mean. I can make a cylinder and it becomes perfectly round. While the lampshade gets a "polygon" look to it.

Well gonna try the last 4.x update and just use that when ever I want to make spiralized stuff.... I just don't understand why they would change the way it works so fundamentally with... As far as I can see. Worse quality in the end.

[Dustin 178]

5.5 Stable - was just released a few hours ago.
Maybe try updating to this version and see if its resolved?

[Slashee_the_Cow 541]

3 hours ago, Dustin said:

5.5 Stable - was just released a few hours ago.
Maybe try updating to this version and see if its resolved?

I like your positive outlook on life.

 

But no, behaves exactly the same as it did in 5.5 beta:

bowl with hole.stl