Help Having an issue w/ a support generating where there is nothing to support and cannot "block" it

[TT_Vert 3]

Here you can see the blocker box where it needs to be:

 

Here you can see it still shows it: 

 

 

And here is the location, the walls are all parallel w/ nothing greater than 60deg anywhere near here.

 

I'm not sure if this is a bug or a PEBKAC, anyone have any input?

Thanks much,

Dave

 

Edited August 11, 2022 by TT_Vert

[Smithy 1,146]

Make the support blocker bigger, that it covers the hole.

[TT_Vert 3]

It's not the circle I'm trying to remove support for it.  It's that errant piece BELOW the circle that supports nothing I want to remove.

[Smithy 1,146]

Ahh sorry my fault thought it is the circle.
I am not an Cura support expert, but I can remember that "Support X/Y distance" and "Support Horizontal Expansion" will do what you want.

[TT_Vert 3]

2 minutes ago, Smithy said:

Ahh sorry my fault thought it is the circle.
I am not an Cura support export, but I can remember that "Support X/Y distance" and "Support Horizontal Expansion" will do what you want.

No worries at all. I'm finding it is doing it on a bunch of vertical surfaces.  I will try thi setting   I've not changed the support X/Y distance from default  and I find it very strange that there i no rhyme or reason to this.  I changed orientation and it no longer supports that area but other areas now 😞  These are vertical walls, not overhangs.

 

I tried putting in support blockers (Not that there should be support here) but it has zero effect:

 

 

 

Here you can see these are vertical wall areas:

 

 

 

[TT_Vert 3]

Ok disabling the option "use towers" allowed me to print this as designed.  I'm going to do some testing on this feature to see more about what it is.

 

[Smithy 1,146]

Supports can be confusing and there are a lot of options. I rarely use supports and try to avoid it whenever possible because I hate the post processing 🙂 

 

But great that you found a solution for your problem. Maybe someone else with more experience with the support settings can help. Maybe @GregValiant ?

[GregValiant 1,409]

Hello @TT_Vert and @Smithy.

Sometimes it's hard to figure out what Cura is doing with the supports.  That particular model is kind of low resolution as witnessed by the coarse triangles that comprise it.  I think that is part of it.

It appears that the triangles of the top and bottom overhanging features line up the same but the triangles of the middle feature don't line up with those of the top and bottom.  So Cura is seeing a line going across that is sticking out past the points (vertexes) of the middle feature and Cura wants to support it because that's what the math says to do.  It looks like it's supporting air because certain settings (min XY distance for instance) is keeping the support away from where Cura has designed it to go.

Another problem with that part is the trapped supports that go behind the middle "T" feature.  It will be tough getting those suckers out.  Unfortunately, they are required because the vertical portion prints first and several layers later the connector to the main body prints.

Talking about this would likely just get more confusing.  Post that model file here and I'll take a stab at it.  I can tell you now though, one of my suggestions might be to make those "T" sections separate details that would glue into place.  As Smithy alluded in regards to getting rid of supports...Just because we can print difficult models doesn't mean we have to.

 

[TT_Vert 3]

4 hours ago, GregValiant said:

Hello @TT_Vert and @Smithy.

Sometimes it's hard to figure out what Cura is doing with the supports.  That particular model is kind of low resolution as witnessed by the coarse triangles that comprise it.  I think that is part of it.

It appears that the triangles of the top and bottom overhanging features line up the same but the triangles of the middle feature don't line up with those of the top and bottom.  So Cura is seeing a line going across that is sticking out past the points (vertexes) of the middle feature and Cura wants to support it because that's what the math says to do.  It looks like it's supporting air because certain settings (min XY distance for instance) is keeping the support away from where Cura has designed it to go.

Another problem with that part is the trapped supports that go behind the middle "T" feature.  It will be tough getting those suckers out.  Unfortunately, they are required because the vertical portion prints first and several layers later the connector to the main body prints.

Talking about this would likely just get more confusing.  Post that model file here and I'll take a stab at it.  I can tell you now though, one of my suggestions might be to make those "T" sections separate details that would glue into place.  As Smithy alluded in regards to getting rid of supports...Just because we can print difficult models doesn't mean we have to.

 

Thanks for the reply.  By low resolution do you mean the layer height?  if so yeah, I'm at .030mm layer height.  The way the supports are (Probably because the thinness of that channel it just supported the overhang, not the area inside of the channel.  I checked this when slicing. The supports worked perfectly and also came out easily w/o blocking the channel at all.  The LEDs slide right in.  Of course I ran out of filament and had to change colors.  This isn't anything that needs to be cosmetically perfect though.

 

[GregValiant 1,409]

By "Low resolution" I meant the STL file.  Low resolution results in larger facets on curves and cylinders but a smaller file size.  Higher resolution results in more triangles, smaller facets, but larger file size.  It's a function of the export utility from CAD.

 

 

[TT_Vert 3]

3 hours ago, GregValiant said:

By "Low resolution" I meant the STL file.  Low resolution results in larger facets on curves and cylinders but a smaller file size.  Higher resolution results in more triangles, smaller facets, but larger file size.  It's a function of the export utility from CAD.

 

 

Interesting.  I use space claim, i wonder if i can change that and if it'd benefit me any.

 

Davae

[GregValiant 1,409]

In the AutoCAD STL export utility the setting is called "Facet Resolution".

The model on the left was exported with the FACETRES at 0.25 and the model on the right had the FACETRES set to 10.00.

The model on the right would print as a "smoother" model as the sides of the triangles that comprise the chords of the diameter are much shorter.  A high resolution STL gives a high resolution print.  The gcode files can be much larger and in the case of these two - the low res gcode was 4.5mb and the high res gcode was 9.7mb.  The print time was about the same.

[TT_Vert 3]

I am not sure if this is the same thing as you have.   This is under STL file options.  It says "export current graphics" so that makes me feel this isn't it.  What do you think?    This wasn't checked so i feel it isn't it.

Edited August 12, 2022 by TT_Vert

[GregValiant 1,409]

I would say just go with "Fine" and export that model you printed and then change it to "Coarse" and export the same model again.  That's what I did for that comparison view.  I used MS 3D Builder but you can open the STL files in Cura and put them side-by-side.  In the "Prepare" screen you should see that the Fine model isn't nearly as faceted as the Coarse model.  Curves and cylinders really show the difference.

[TT_Vert 3]

Yeah that's exactly what I did.  That definitely changed the gcode size and I can see some shading differences.  Thank you for pointing this out to me!  Curious how much better my prints may look due to the higher resolution.

 

Fine:

 

 

Medium:

[GregValiant 1,409]

That's it.  That part won't print anywhere near as faceted as the first model.