Cura places supports in the wrong places that are not marked red

[Skas 0]

I was slicing my project as usal and noticed something strange. When importing my stl model in cura and setting my overhang support angle above 45 degrees (my model has a chamfer that is 45 degrees overhang) the overhang was not red indicating that there will be no supports generated. However when slicing there were still supports being generated. I tried increasing support overhang angle even more above 45 degrees and supports stopped generating at 88 degrees. 

 

I made a test model that has a chamfer with an overhang angle of 45 degrees and right above it a cutout that needs support since it is at 90 degrees. This model has that problem when slicing and changing support overhang angle, the supports are still generated at that 45 degree chamfer.

 

Next i made a test model that doesn't have a cutout above a chamfer and the model sliced fine. When changing overhang angle above 45 degrees the supports are not generated and that area is not red anymore.

 

Model i have problem with:

 

Notice how the 45 degree chamfer is shaded red, indicating that supports will be generated, and after slicing the supports are generated.

 

Now this is a case where i increase the support overhang angle above 45 degrees in which case the chamfered area is no longer red, but the supports are still generated:

 

Next i made a test model that doesn't have the cutout above chamfered area and it sliced fine. The supports were generated if i put support overhang angle to 45 degree, and anything above that the supports didn't generate (as suspected).

 

Here is a picture of the model i didn't incounter problems with:

 

if i change support overhang angle above 45 degrees support are not generated which is correct:

 

I also tryed changing support placement to "touching build plate" but it still generated support with the first model i have problems with. 

The second model works and i have no problem with it.

 

My questions are:

Is it possible to only generate supports in the slot above the chamfer in the first design?

Is it possible that this is happening because one model has a slot above a chamfered design?

I also have a custom build plate model of ender 3 pro, is it possible that these problems are caused by this?

 

I attached:

-cura profile

-both models i tested this with in stl format and cura project format

-my cura version is 5.4.0

 

Thank you very much for your help! 🙂

Devil design PLA 215°.curaprofile Test model with problems.stl Test model with no problems.stl CE3PRO_Test model with problems.3mf CE3PRO_Test model with no problems.3mf

[Torgeir 248]

Hi @Skas.

 

Welcome in here.

 

My best advice, stay away from Cura 5.40, this advice cause this version of Cura have some nasty issues..

 

If you just need to use the later version of Cura due to the line width control -then use version 5.2.2 as this version handle support very well.

 

Thanks

Torgeir

 

[Cuq 205]

In Cura a support start from the builtplate to the supported area. So as you have define a support Expansion the support start from the Builtplate .  

 

Fix the support horizontal expansion value to 0 to get the right result :

Edited September 1, 2023 by Cuq

[Slashee_the_Cow 354]

If you use tree supports, they should be created outside of the model and only branch up to the overhang where needed.

[Skas 0]

Thank you all for help! Reducing support horizontal expansion  to 0 seemed to fix the issue. What intrigues me is that cura will show where supports will be generated with red areas, but with support horizontal expansion those areas that are not shaded red will still generate supports.

[gr5 2,196]

I think the lower support was in some strange way supposed to support the upper support.  If they weren't right above each other I think there would have been zero support in the lower area.  If that makes some kind of weird sense.