Perimeters being printed double

[Verne64 0]

I am using Cura to slice for a UMO+, equipped with a 1,8mm nozzle (drilled out a standard nozzle). The model I am using to print, is basically a cilinder that has a wall thickness of 1,8mm modeled into it. Needless to say, I want to print this with a single wall of 1,8 mm.  

 

When I slice it, Cura sends the nozzle around the circle twice, both times extruding filament, which results in a (sloppy) wall thickness of around 3,6 mm and horrible looking Z scar. As can be seen in the attached image, it isn't printing two perimeter lines next to each other as it would normally do, but printing the same line again in the same layer. It can be seen when clicking the play button in the layer view and when the printer is running. When I use the same settings with a closed solid model and let Cura determine wall thickness etc., it all works like I would expect, 1 perimeter line and nice clean print results. 

I think I have pretty much tried varying all the settings connected to the wall thickness (number of perimeters, compensate wall thickness, print thin lines, fill gaps etc, line width.) and the calculation of the number of perimeters. Also in the modeling of the wall thickness (tried slightly above and below 1,8). The obvious answer would be to use a closed solid, but I need some of the features that can only be included when modeling the wall thickness. 

 

Can anybody tell me why Cura will double extrude these lines? What could I change to get it to cleanly extrude the wall in a single line/pass?

 

 

[gr5 2,210]

I'm not an expert on thin walls but maybe try setting Minimum Wall Flow to 50.  And if that doesn't help @smartavionics understands this much better than me.

[Verne64 0]

That does 

On 6/14/2019 at 10:59 PM, gr5 said:

I'm not an expert on thin walls but maybe try setting Minimum Wall Flow to 50.  And if that doesn't help @smartavionics understands this much better than me.

That does fix the behavior in the layer preview! I'lle make a test print somewhere this week, but suspect it will be fine. Thank you!

 

It seems to work from 15% up. Does that mean that the second pass was being printed at lower than 15% flow? In practice, the printer seemed to be pushing through the filament through at the same rate in both directions.

 

 

[ftoons 5]

Same problem, fixed with same solution. 

Was printing a single wall cube (not in spiralize mode) and the nozzle did a second pass on all layers. 

Changed the minimum wall flow from 0 to 15% made is a single pass.

Thank you gr5.