Problem with step in vertical wall equal to wall thickness

[weevil 1]

Hi All

 

I have a part with a cylindrical section which includes a step down to a reduced diameter, then back up to the original diameter.  When I slice it, Cura (4.3.0) fails to put top and bottom layers around the stepped down region.  This means that, apart from the infill, there is no connection between the general diameter and the stepped down region. 

 

 

My screenshot shows the problem.

(BTW, the part does have infill---grid, if it matters---but I've not shown in the attached screenshot.  Also, Cura does put the top layers in correctly at the very top of the part which link the outer diameter to the inner, but my screenshot is sectioned a few layers below that in order to show the disconnect at the top of the reduced diameter region.)

 

I suspect that the problem is related to the fact that, by coincidence, the step size is the same as the wall thickness, at 0.9 mm.

 

I don't need a solution right now, because I've adjusted the model, but I'd be interested to hear whether this is known problem, as there are likely to be occasions where I don't have the freedom to design the problem out.  I couldn't find anything on this forum under "step wall thickness".

 

(Apologies if there's a repeated image below this line.  I've edited my post to delete it twice, but it keeps coming back!)

Edited November 1, 2019 by weevil

[burtoogle 516]

Hello @weevil, could you please save the project file (File -> Save) and attach the .3mf file to this thread so we can check the model and settings. Thanks.

[weevil 1]

Happy to...

UM3E_Test Platform - Failed Step.3mf

[burtoogle 516]

Try setting the skin removal width to 0.

 

[weevil 1]

Thanks, burtoogle, that's fixed it.

 

It hadn't occurred to me that an Infill setting would affect the Shell.  I'd assumed Shell was king.  So much still to learn  🙂

 

 

[burtoogle 516]

Well, I think that setting was possibly in the shell category before and they moved it? (might be wrong about that). I agree that it doesn't make sense to have it in the infill category as it's not affecting the infill but the skin.

[Omibus 0]

Is there no feature/setting in cura to set a minimum shell thickness (which is then meassured not only horizontaly = current wall thickness setting or vertically = current top/bottom layer setting, but also in all other directions).

 

Technically, cura would just have to put a litte sphere (with a radius of the minimum shell thickness setting) on every outer point of the part. All possible spheres have to lie within the walls or top/bottom layers.

 

 

Example with 3 outer wall lines in the spot of the corner: