<p>I'm not really sure if i get you right but it seems like you gotta switch on support material. That's all. Correct me if I'm wrong but it sounds like very common situation where some parts are hanging like your yellow disks.</p>

<p>Otherwise if your model is going to be closed at the bottom and at the top you can mock support on your own to have better control of it. How? Just add hollow cylinders under your disk so in fact cylinder will stay on the bottom layer then its walls will be support and finally your yellow disk will be a top cover of the cylinder. I hopw you can imagine that properly.</p>

<p>Another way is to design support elements wich would grow out of walls and this way support your disks</p>

<p><a href="https://i.sstatic.net/p9Z7F.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/p9Z7F.png" alt="enter image description here"></a></p>

<p>Maybe if you would explain a bit more, what the model is then I could support you more.</p>

<p><strong>[edit]</strong></p>

<p>To make it more automatic, you could try to use parametric CAD apps. I would say, Autodesk Inventor is one which I can suggest. You can use for example its Ribs functionality as support (varsion C).</p>

<p><strong>[edit2]</strong></p>

<p>After Tormod Haugene's and tbm0115's comments I decided to fill some gaps in my answer. Here go pros and cons of options A, B and C.</p>

<ul>
<li><strong>option A</strong></li>
</ul>

<p>The simplest one and more or less automatic one. Which means when user add support then this option will be a result of it. Of course if user needs to have support only for the disk but over the disk there will be... a "ceiling" then option A cannot use regular support as it will generate a support also for the ceiling. For such situation user needs to add a cylinder manually (filled one) or</p>

<ul>
<li><strong>option B</strong></li>
</ul>

<p>User can add hollow cyliner (just its walls). This option can give similar or higher stiffness as regular support because solid walls increase endurance tahn thin support grid.</p>

<ul>
<li><strong>option C</strong></li>
</ul>

<p>This option (my personal choose) has some advantages unavailable in A or B option. First - support doesn't have to have "ground" base. It means the yellow disk can really hang even if there is no bottom layer at all. Second - it joins walls with disk and walls together so the stiffness concerns other surfaces.</p>

<p>Depending on needs the cylinder (option A or B) can be transformed into a cross or pillar (thinner than cylinder itself). It can be more taper expandint to the top or to the bottom.</p>

<p>There could be even option where the above one would be joined with option C. So these (3) ribs would raise from the bottom but not from the walls.</p>

CC BY-SA 3.0
2016-07-11T10:22:15.570Z
Thank you, this is what I'm doing right now, I just wanted something automated (the real model is much more complicated and requires a lot of internal cylinders and cones)
Nir
CC BY-SA 3.0
2016-07-11T11:12:45.063Z
Automated you say. Check meshmixer application. It can surprise you in terms of support material :)
darth pixel
CC BY-SA 3.0
2016-07-12T08:40:02.457Z
@darthpixel mashmixer is great for support, however, I didn't find any feature there that places support/infill inside the object
Nir
CC BY-SA 3.0
2016-07-12T08:56:50.887Z
@Nir I'm quite sure that MM produces inside-support on its own, I mean without any extra option for such support. Objects I managed in MM had it. But the real question is, why don't you just support your disk manually with kinda pillar or cylinder. If it's interior (I assume invisible) then what is the problem. Gimme more light on your model please so I could help you better.
darth pixel
CC BY-SA 3.0
2016-07-12T10:17:09.047Z
@darthpixel the specific model has lots of those surfaces, sketchup is rather bad at designing small internal spaces and it seems like something a slicer could do automatically.
Nir
CC BY-SA 3.0
2016-07-12T10:17:54.347Z
@darthpixel also MM does not add support inside solids, it only adds internal support if I create holes inside the part - and at that point I might as well create the support myself
Nir
CC BY-SA 3.0
2016-07-11T09:29:30.033Z
2016-07-11T20:14:47.990Z
2016-07-11T20:14:47.990Z
darth pixel
<p>In <a href="http://slic3r.org/" rel="nofollow noreferrer">Slic3r</a>, this can be solved by selecting a suited infill pattern and density, while enabling the <a href="http://manual.slic3r.org/expert-mode/infill-optimization" rel="nofollow noreferrer">only infill where needed</a>-option:</p>

<ul>
<li><p>Personally, I have found the <a href="http://manual.slic3r.org/expert-mode/infill" rel="nofollow noreferrer">concentric infill pattern</a> to provide good support for models with internal overhang, although other patterns might work as well. I would try different patterns at ~30% infill and inspect the result in the print previewer. </p></li>
<li><p>The option of using <a href="http://manual.slic3r.org/expert-mode/infill-optimization" rel="nofollow noreferrer">only infill where needed</a> will generate internal supports where needed without filling the entire model. That could be what you are looking for. </p></li>
</ul>

CC BY-SA 3.0
2016-07-11T12:00:29.817Z
Additionally, I believe you can add supports in Slic3r, and then export it as an STL to used in Cura. I will verify that later, though.
Tormod Haugene
CC BY-SA 3.0
2016-07-11T12:34:31.733Z
@TH no doubt. It's Export STL on the right panel on plater.
darth pixel
CC BY-SA 3.0
2016-07-12T08:33:36.393Z
Thanks, but Slic3r "only infill where needed" also place infill below surfaces that can be printed just fine with normal bridging, in my case this option will give almost the same result as using global infill
Nir
CC BY-SA 3.0
2016-07-12T08:36:41.113Z
@Nir, did you try using different infill patterns as well?
Tormod Haugene
CC BY-SA 3.0
2016-12-30T04:05:09.293Z
@TormodHaugene It would be awesome if this worked, but as of today, no, Slic3r can NOT export an STL with support material. Exporting the STL just exports the objects imported into the tray. There is a feature request for this here: https://github.com/alexrj/Slic3r/issues/2575
wjl
CC BY-SA 3.0
2016-12-30T08:21:11.717Z
@wjl, I obviously didn't do my fact checking properly. Thanks for clearing that up!
Tormod Haugene
CC BY-SA 3.0
2016-07-11T11:56:55.333Z
2016-12-30T08:23:07.537Z
2016-12-30T08:23:07.537Z
Tormod Haugene
<p>In Cura 2 you can do several things:</p>

<ol>
<li><p>Design internal support pillars, and make them an Infill Mesh via the Per-object settings. I suggest you also reduce the top/bottom thickness and Wall thickness of the infill mesh.</p></li>
<li><p>Enable Hollow Out Objects and enable support.</p></li>
<li><p>Enable gradual infill: increase the Gradual Infill Steps. Although this will still make infill everywhere it will drastically reduce the infill where it's less needed.</p></li>
</ol>

CC BY-SA 3.0
2017-07-30T10:06:57.337Z
2017-07-30T10:06:57.337Z
Tim Kuipers
<p>I'm currently designing a very large and complicated model, because it's large and should be strong enough completely hollow I want to print it with no infill to save material.</p>

<p>However, there are some points in the model where there are indentations in the top shell.</p>

<p>The bottom of those indentations are lower then the surrounding shell (pretty mush the dictionary definition of indentation) and so they are printed earlier with nothing to connect to.</p>

<p>For example, in the image below from Cura's layer view you can see two round surfaces just hanging in mid air</p>

<p><a href="https://i.sstatic.net/d4Rrm.png" rel="noreferrer"><img src="https://i.sstatic.net/d4Rrm.png" alt="Surface in mid air"></a></p>

<p>Obviously this can't be printed.</p>

<p>What I'm currently doing is designing internal spaces inside the model where the internal space shell is holding the "detached" surfaces.</p>

<p>What I want is a mostly automatic process that will generate a support structure inside where needed or that will generate infill but only between the floating surface and the nearest solid shell below it.</p>

<p>Reorienting the model is not an option because a. it wouldn't fit on the build plate and b. even if it did it has a lot of internal parts with different orientations so it would just move the problem from one part of the model to another. </p>

<p>I usually use SketchUp for designing and Cura for slicing so I prefer something I can do in Cura - but since I strongly suspect this can't be done in Cura I'll accept answers that work with other tools</p>

<3d-design><support-structures><infill>
How to add internal supports/localized infill, preferably in Cura?
Nir
# How to add internal supports/localized infill, preferably in Cura?

(Asked by: username_0 on 2016-07-11)

I'm currently designing a very large and complicated model, because it's large and should be strong enough completely hollow I want to print it with no infill to save material.

However, there are some points in the model where there are indentations in the top shell.

The bottom of those indentations are lower then the surrounding shell (pretty mush the dictionary definition of indentation) and so they are printed earlier with nothing to connect to.

For example, in the image below from Cura's layer view you can see two round surfaces just hanging in mid air

[![Surface in mid air](https://i.sstatic.net/d4Rrm.png)](https://i.sstatic.net/d4Rrm.png)

Obviously this can't be printed.

What I'm currently doing is designing internal spaces inside the model where the internal space shell is holding the "detached" surfaces.

What I want is a mostly automatic process that will generate a support structure inside where needed or that will generate infill but only between the floating surface and the nearest solid shell below it.

Reorienting the model is not an option because a. it wouldn't fit on the build plate and b. even if it did it has a lot of internal parts with different orientations so it would just move the problem from one part of the model to another.

I usually use SketchUp for designing and Cura for slicing so I prefer something I can do in Cura - but since I strongly suspect this can't be done in Cura I'll accept answers that work with other tools

**Tags:** 3d-design, support-structures, infill

---

## 3 answers

### Answer by username_1 on 2016-07-11. Score: 3

I'm not really sure if i get you right but it seems like you gotta switch on support material. That's all. Correct me if I'm wrong but it sounds like very common situation where some parts are hanging like your yellow disks.

Otherwise if your model is going to be closed at the bottom and at the top you can mock support on your own to have better control of it. How? Just add hollow cylinders under your disk so in fact cylinder will stay on the bottom layer then its walls will be support and finally your yellow disk will be a top cover of the cylinder. I hopw you can imagine that properly.

Another way is to design support elements wich would grow out of walls and this way support your disks

[![enter image description here](https://i.sstatic.net/p9Z7F.png)](https://i.sstatic.net/p9Z7F.png)

Maybe if you would explain a bit more, what the model is then I could support you more.

**[edit]**

To make it more automatic, you could try to use parametric CAD apps. I would say, Autodesk Inventor is one which I can suggest. You can use for example its Ribs functionality as support (varsion C).

**[edit2]**

After Tormod Haugene's and tbm0115's comments I decided to fill some gaps in my answer. Here go pros and cons of options A, B and C.

* **option A**

The simplest one and more or less automatic one. Which means when user add support then this option will be a result of it. Of course if user needs to have support only for the disk but over the disk there will be... a "ceiling" then option A cannot use regular support as it will generate a support also for the ceiling. For such situation user needs to add a cylinder manually (filled one) or

* **option B**

User can add hollow cyliner (just its walls). This option can give similar or higher stiffness as regular support because solid walls increase endurance tahn thin support grid.

* **option C**

This option (my personal choose) has some advantages unavailable in A or B option. First - support doesn't have to have "ground" base. It means the yellow disk can really hang even if there is no bottom layer at all. Second - it joins walls with disk and walls together so the stiffness concerns other surfaces.

Depending on needs the cylinder (option A or B) can be transformed into a cross or pillar (thinner than cylinder itself). It can be more taper expandint to the top or to the bottom.

There could be even option where the above one would be joined with option C. So these (3) ribs would raise from the bottom but not from the walls.

> **Comments:**
> **username_0**: Thank you, this is what I'm doing right now, I just wanted something automated (the real model is much more complicated and requires a lot of internal cylinders and cones)  
> **username_1**: Automated you say. Check meshmixer application. It can surprise you in terms of support material :)  
> **username_0**: @darthpixel mashmixer is great for support, however, I didn't find any feature there that places support/infill inside the object  
> **username_1**: @Nir I'm quite sure that MM produces inside-support on its own, I mean without any extra option for such support. Objects I managed in MM had it. But the real question is, why don't you just support your disk manually with kinda pillar or cylinder. If it's interior (I assume invisible) then what is the problem. Gimme more light on your model please so I could help you better.  
> **username_0**: @darthpixel the specific model has lots of those surfaces, sketchup is rather bad at designing small internal spaces and it seems like something a slicer could do automatically.  
> **username_0**: @darthpixel also MM does not add support inside solids, it only adds internal support if I create holes inside the part - and at that point I might as well create the support myself  

---

### Answer by username_2 on 2016-07-11. Score: 3

In [Slic3r](http://slic3r.org/), this can be solved by selecting a suited infill pattern and density, while enabling the [only infill where needed](http://manual.slic3r.org/expert-mode/infill-optimization)-option:

* Personally, I have found the [concentric infill pattern](http://manual.slic3r.org/expert-mode/infill) to provide good support for models with internal overhang, although other patterns might work as well. I would try different patterns at ~30% infill and inspect the result in the print previewer.
* The option of using [only infill where needed](http://manual.slic3r.org/expert-mode/infill-optimization) will generate internal supports where needed without filling the entire model. That could be what you are looking for.

> **Comments:**
> **username_2**: Additionally, I believe you can add supports in Slic3r, and then export it as an STL to used in Cura. I will verify that later, though.  
> **username_1**: @TH no doubt. It's Export STL on the right panel on plater.  
> **username_0**: Thanks, but Slic3r "only infill where needed" also place infill below surfaces that can be printed just fine with normal bridging, in my case this option will give almost the same result as using global infill  
> **username_2**: @Nir, did you try using different infill patterns as well?  
> **username_3**: @TormodHaugene It would be awesome if this worked, but as of today, no, Slic3r can NOT export an STL with support material. Exporting the STL just exports the objects imported into the tray. There is a feature request for this here: https://github.com/alexrj/Slic3r/issues/2575  
> **username_2**: @wjl, I obviously didn't do my fact checking properly. Thanks for clearing that up!  

---

### Answer by username_4 on 2017-07-30. Score: 1

In Cura 2 you can do several things:

1. Design internal support pillars, and make them an Infill Mesh via the Per-object settings. I suggest you also reduce the top/bottom thickness and Wall thickness of the infill mesh.
2. Enable Hollow Out Objects and enable support.
3. Enable gradual infill: increase the Gradual Infill Steps. Although this will still make infill everywhere it will drastically reduce the infill where it's less needed.


---

