Support layers missing when interface is enabled

[RensoPiano 0]

Hi everyone.

 

For a while now I've been running into this problem with missing support layers. This had never been an issue in Cura 5.1.0 and before, but every version since has this same issue. Never could figure out the problem, untill recently I found out it has something to do with the 'Support Interface' setting. 

 

When I enable 'Support Interface' with 'Enable Support Roof' on, the slicer leaves a gap of a couple of layers between supports. If I leave 'Enable Support Roof' off it does connect the supports.

 

Again, this has only been a problem after version 5.1.0.

 

Anyone know what I can change in the settings to help this problem? I want the whole supports to be connected, because otherwise the support structures get knocked over frequently or torn loose. Using PVA for supports fyi.  I've added the project file if needed.

 

Thanks in advance!

2024-01-08_UltiMaker Cura 5.6.0._troubleshoot layers missing.3mf

[Slashee_the_Cow 619]

You have Support > Support Layer Thickness set to 0.2mm but your layer height set to 0.1mm. This will cause it to print a thicker support layer every second layer, but this is represented in the gcode viewer by just printing support every second layer (not covering both, because it just shows what gets printed that layer).

 

This setting should be unaffected by whether you're using a roof or not (and disabling the roof in your example file - thanks for providing one, BTW, it shows the same thing; support printed every second layer).

[RensoPiano 0]

Thanks for taking a look and helping out, but this is not the problem I'm having. My problem is about the layers between the support roof and the next support structure.

 

In 5.1.0. this used too be filled up with support, but after 5.1.0. this is just empty space (added some screenshots, hopefully this makes it more clear). I would like a result where the whole support structure is connected.

[Slashee_the_Cow 619]

Ah, now I get you (having little to no spatial reasoning ability doesn't help the situation usually).

 

Playing around with settings (sometimes the best way to solve a problem): it looks like all these little bits of structure are causing the problem:

There's a particularly bad one here:

 

Okay, I'll admit I'm not 100% sure what the problem is. Probably something to do with support never extending outside its footprint but that footprint not accounting for interface horizontal expansion.

 

How to fix it?

a) Turn down Support Interface Horizontal Expansion to 0mm. This means interface will still be generated where it's needed but outside that area it's not competing for space, the regular support just says "don't worry bro, I got this":

 

b) Increase Support Horizontal Expansion by 2.4mm according to my testing (has to be higher than the interface expansion plus room regular support) to account for the interface expansion. This is the "there's room for both of us in this playground!" approach. The disadvantage is that you have a bigger cocoon around your model which increases material used and print time:

 

c) A bit of both: here I've set Support Interface Horizontal Expansion to 1mm and increased Support Horizontal Expansion by 1.4mm:

 

d) Use trees:

But I'm guessing if you wanted that approach you'd have done it by now.

 

Hope this helps more than it confuses!

[GregValiant 1,489]

Sorry Slashee.  I don't think anything will help make this less confusing.

 

Cura won't build support on a support interface so yes, the "Interface" Horizontal Expansion needs to be less than the regular Support Horizontal Expansion.

How much less depends on the Support Wall Line Count (coupled with the XY distance).

With the Support Wall Line Count at "1" the Interface Horizontal Expansion can be 1 line width less than the Support HE.  If you happen to have Support Wall Line Count at "0" then the Interface HE needs to be 3 line widths less.

 

In that project, the Support HE is 2.0 and the Support Wall Count is 0 so the Interface HE needs to be 0.8mm ("3 * Line Width" less than the Support HE).  That will provide supports for the supports.

 

 

[RensoPiano 0]

Trying out the above suggestions, it looks like reducing the 'Support Interface Horizontal Expansion' solved the problem.

 

I didn't know about the fact Cura doesn't build support on a support interface. This must have been a more recent change, because with older versions this wasn't an issue. But knowing this I can just keep the interface horizontal expansion set to 0 and have no issues.

 

Thank you both for your time!