<h3>Summary:</h3>
<p>I am asking if there are any guidance documents or videos or articles you can point me to, or even just an answer here from someone, about what are some optimal ways or rules of thumb to use internal structures in a CAD model so that when it prints it will give maximal strength.</p>
<p>This question is <strong>not</strong> about infill patterns or infill percentages.</p>
<h3>Detail:</h3>
<p>We all know that plain solid regions of a print will be filled with either wall (shell) layers or infill patterns and different infill patterns have different strength properties but generally the more wall layers you use the greater the strength (compared to using denser infill although the issue gets a little more complex when considering wall layers vs 100% infill. I am <strong>not</strong> asking about this at all.</p>
<p>The fact that most strength generally comes from proper wall/shell layers as opposed to infill percent suggests that greater strength can be provided by using the CAD software to 'fill' otherwise plain solid areas of a model with definite hollow structures - like small tubes or spheres - which will get printed with proper shell layers when sliced and so provide the strength of shell layers inside solid regions of the model that would otherwise get filled with standard slicer infill patterns - and thereby produce greater strength than using infill (at percentages lower than 100% at least).</p>
<p>What I am asking is are there any rules or tools or guides about the 'best' ways to design such (possibly, but not necessarily, hidden) internal structures for strength in various circumstances? Any videos or online guides or papers you can point me to? Or any tips from your own experience?</p>
<p>I have done YouTube and Google searches but they just keep chucking up this infill vs wall layers stuff and other things about generally strengthening 3D prints (annealing, inserting metal rods, coating with epoxy, etc.) which are irrelevant to my specific question.</p>

CC BY-SA 4.0
2024-08-21T16:34:02.240Z
I don't have a link handy but I believe Slant 3D had a video on this topic. Not terribly scientific or anything but maybe a starting point.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2024-08-21T19:50:08.757Z
@R..GitHubSTOPHELPINGICE Thanks - I saw that video but he basically just introduces the topic as a way of 'forcing' slicers to use extra outer wall layers in cases where you might not be in control of the slicer settings (i.e. when sending models out to be printed by a company). I would like learn principles beyond the basic concept.
WildCat
<cad><print-strength>
Any guidance on the use of internal structures in the CAD model to enhance strength in plastic FDM 3D prints (not infill patterns vs wall layers)?
WildCat
# Any guidance on the use of internal structures in the CAD model to enhance strength in plastic FDM 3D prints (not infill patterns vs wall layers)?

(Asked by: username_0 on 2024-08-21)

### Summary:

I am asking if there are any guidance documents or videos or articles you can point me to, or even just an answer here from someone, about what are some optimal ways or rules of thumb to use internal structures in a CAD model so that when it prints it will give maximal strength.

This question is **not** about infill patterns or infill percentages.

### Detail:

We all know that plain solid regions of a print will be filled with either wall (shell) layers or infill patterns and different infill patterns have different strength properties but generally the more wall layers you use the greater the strength (compared to using denser infill although the issue gets a little more complex when considering wall layers vs 100% infill. I am **not** asking about this at all.

The fact that most strength generally comes from proper wall/shell layers as opposed to infill percent suggests that greater strength can be provided by using the CAD software to 'fill' otherwise plain solid areas of a model with definite hollow structures - like small tubes or spheres - which will get printed with proper shell layers when sliced and so provide the strength of shell layers inside solid regions of the model that would otherwise get filled with standard slicer infill patterns - and thereby produce greater strength than using infill (at percentages lower than 100% at least).

What I am asking is are there any rules or tools or guides about the 'best' ways to design such (possibly, but not necessarily, hidden) internal structures for strength in various circumstances? Any videos or online guides or papers you can point me to? Or any tips from your own experience?

I have done YouTube and Google searches but they just keep chucking up this infill vs wall layers stuff and other things about generally strengthening 3D prints (annealing, inserting metal rods, coating with epoxy, etc.) which are irrelevant to my specific question.

**Tags:** cad, print-strength

> **Comments:**
> **username_1**: I don't have a link handy but I believe Slant 3D had a video on this topic. Not terribly scientific or anything but maybe a starting point.  
> **username_0**: @username_1 Thanks - I saw that video but he basically just introduces the topic as a way of 'forcing' slicers to use extra outer wall layers in cases where you might not be in control of the slicer settings (i.e. when sending models out to be printed by a company). I would like learn principles beyond the basic concept.  

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## 0 answers

