Incorrect number of walls sliced

[JoeJoe 0]

Recently switched computers and lost old profile. Trying to slice some items with a modeled thickness of 1.2mm, but Cura is only putting in 2 walls instead of 3. I feel like this didn't happen on my older version of Cura on the prior computer (as i previously modeled test objects/cubes/walls), but can't be sure as it's been some months. Is there some way to address this? If the wall is 1.2mm and i have a 0.4mm nozzle (and have that set in Cura) I should get 3 walls (currently set to print 3 walls anyways).

 

In the pic here you can see an M, all parts of this are 1.2mm wide, yet Cura decided to do 2 walls and not three. I also tried one at .4mm wide and cura just decided the wall part didn't exist.

 

Use "Print thin walls" you are probably about to say. So when i cut that on, this weirdness happens. Below is a shot looking up the Y axis at the bottom of that M. You can see from the grey outline that I have a chamfer on the M (as this will be pressed into clay). Why on the 3rd layer is it suddenly pulling in just to put a fatter layer above it? (I have adaptive layers on in this shot, but even with that off, same thing happens). Further there is a significant gap between the grey model ghost and the sliced print lines all around, which seems like Cura is purposefully slicing things shy of the model dimensions. I cannot figure out what setting is causing this that is now different.

 

Also print thin walls does this weird striped and squashed bit which makes no sense to me. What is going on here?

 

 

Here's the model in fusion 360 that i exported as 3mf to then slice in Cura

 

[JoeJoe 0]

oh also, i tried setting line width to .35 and to .30 and that change did nothing, still only doing 2 walls instead of what should now be 4. I am very confused.

[GregValiant 1,330]

You should switch to the Arachne Engine Beta II version of Cura for this model.  It is capable of filling in the middle "third" wall.

 

With the current version set to two walls consider a capital "I".  The vertical leg of the letter has two walls on the left and two walls on the right for a total of 4 walls.  If the vertical leg is 1.2mm wide then 4 walls won't fit and the center remains empty unless you use "Fill gaps between walls = Everywhere".  Essentially, the program only does an even number of walls across an object.