Minimum Infill Area

[Guest Lemaru2]

Hi,

 

I was looking to use the Minimum Infill Area setting so that some or the smaller areas of my models are printed using skin rather than infill. This option seems to work well in Slic3r but when trying it in Cura I have found that it sometimes causes there to be gaps in the top layer of skin. After looking up the setting I can see that people have reported this function no longer works correctly.

 

If this is the case, is there any other way to be able to achieve this without Cura removing my top surface skin from any areas?

You can see in the attached picture that with Minimum Infill Area set to 0 the circular areas are printed with skin (as expected), when  value is set for the Minimum Infill Area, the skin in then missing. 

 

I have also attached an STL of a screw pillar that is part of one of my models. I would ideally like for this to print solid but for the rest of the print to be infilled like normal. A Minimum Infill Area of 70mm^2 usually achieved this but at the sacrifice of other areas of the model potentially missing its top skin.

 

Thanks

 

Pillar.stl

[Brulti 176]

There is a way to have CURA do different infill for different parts of the same print, I saw that in one of the CURA blogs...

 

https://ultimaker.com/en/blog/52484-discover-ultimaker-cura-32

 

It's called Modify settings for infill of other models - mesh will be printed as infill in sections that mesh overlap.

Basically, you add a mesh that overlaps with your model, and you can tell CURA that you want the infill of whatever is inside the mesh to be different than the rest of the model. I know there is an explanation somewhere on the forums or the blogs with a video or a gif, but I can't seem to find it...

 

EDIT: Found a video: https://www.youtube.com/watch?v=PUwf79wySUY

Edited May 29, 2018 by Brulti

[burtoogle 508]

Hello @Lemaru. Yes, the Minimum Infill Area settings does appear to be broken. However, all is not lost. You can achieve your desired aim by setting the Skin Expand Distance to something like 2mm. Have a play with it!

[Guest Lemaru2]

17 hours ago, smartavionics said:

Hello @Lemaru. Yes, the Minimum Infill Area settings does appear to be broken. However, all is not lost. You can achieve your desired aim by setting the Skin Expand Distance to something like 2mm. Have a play with it!

 

Thanks, though I have just been playing with that setting and it appears to have no affect regardless of what it is set to, The pillars in the model still remain infilled rather than solid. Have attached a screenshot

 

The issue I have is that unless these are printed solid they are either weak or have gaps in the surface, when using the Minimum Infill Area it prevents this from happening. Is there a bug logged for this issue and will it ever get fixed as it is a useful feature.

 

[burtoogle 508]

5 minutes ago, Lemaru said:

Thanks, though I have just been playing with that setting and it appears to have no affect regardless of what it is set to, The pillars in the model still remain infilled rather than solid. Have attached a screenshot

 

The issue I have is that unless these are printed solid they are either weak or have gaps in the surface, when using the Minimum Infill Area it prevents this from happening. Is there a bug logged for this issue and will it ever get fixed as it is a useful feature.

 

Ah, I failed to read your post correctly, I thought you were worried about the skin not being complete. If you want the pillars solid you will need to set the infill density suitably high. If you don't want everything filled to the same density you will need to learn about infill meshes.

 

As to your second point, the min infill area feature (currently broken) only applies to infill regions within skins, not to infill regions within walls so even if it was working as expected, it still wouldn't make your pillars solid.

[cjs 34]

26 minutes ago, smartavionics said:

not to infill regions within walls so even if it was working as expected,

May I ask whats the difference between skin and walls? It's a bit confusing why Cura has outer walls, inner walls and skin and each has a bazillion settings (overlap, extra skin...). 

Other Slicers most of the time only have walls or outline or skin. 

[burtoogle 508]

For each layer, the walls are the lines that go around the perimeters of the model and separate the enclosed skin/infill from the air. The region inside the walls can be either skin or infill. Skin is always 100% filled (it's solid) and most models have one or more top and bottom skin layers. Regions within the walls that are not skin will be filled with infill whose density varies depending on the user's requirements.

 

Sorry, I don't understand your second paragraph as walls and outline are the same thing, aren't they?

[cjs 34]

2 minutes ago, smartavionics said:

Sorry, I don't understand your second paragraph as walls and outline are the same thing, aren't they?

Yes they are. I tried to say that most other slicers, I think, don't differentiate between skin and walls like Cura and they just call them outlines,shells or skin. Therefore my confusion. 

Thanks for explaining the Cura specifics! 

 

Do you know why it's useful to have skins and walls separate instead of just using one setting to specify how many outlines the printed object should have? 

[burtoogle 508]

OK, I understand now. It's useful to be able to specify the number of skin layers independently from the number of walls because, sometimes, you want your printed part to have specific physical properties, i.e. strength, quality of surface finish and, so on. For example, if you are printing with a very low infill density but still require a good finish on the top of the model, you would probably want to increase the number of top layers so that the gaps between the infill don't cause the top surface to have dimples. The same model may only require a relatively thin bottom skin so you wouldn't need so many skin layers on the bottom. It would be possible to have a single setting that specifies the thickness of the model's outline (walls and skin) but a lot of the time it would not satisfy the user's requirements of beauty/strength/cost/etc.

[Guest Lemaru2]

1 hour ago, smartavionics said:

 

Ah, I failed to read your post correctly, I thought you were worried about the skin not being complete. If you want the pillars solid you will need to set the infill density suitably high. If you don't want everything filled to the same density you will need to learn about infill meshes.

 

As to your second point, the min infill area feature (currently broken) only applies to infill regions within skins, not to infill regions within walls so even if it was working as expected, it still wouldn't make your pillars solid.

Thank's for the info. It's a shame its broken as I find that setting this to 70mm2 (same as the Slic3r setting) it does exactly what I need, only it sometimes loses areas of top surface skin. I guess I will have to look up about meshes or stick to Slic3r for models like this. 

[Guest Lemaru2]

I have just noticed this explanation of this option on the Cura website. This implies that this feature would do exactly as I need, as the "chimney" in the explanation is no different to my pillars.
 

 

Quote

Minimum infill area

This setting allows filling small areas on a single layer to be printed with skin instead of infill. Take a flat roof with a chimney for example: the chimney is thin and fragile and will be printed completely solid, with skin.

 

I see 3.4 has now been released but nothing in the change log to say this feature has been fixed. Any ideas on when a fix is likely?