<p>I think a general design answer is that it's always better to have a simpler configuration as the default.</p>
<p>In order to perform an overall infill-combined slice the slicer would have to perform at least two additional operations: an additional slice at the multiple height (or an equivalent operation, I am not a slicer developer) for the infill, and then a merge of that with the slice for the shell at the specified layer height. This is more complicated that a single slice at the chosen layer height, ergo it is preferable to default to the simpler option.</p>
<p>That said, I think your own experience is the best testimonial; if you <em>always</em> change the setting and you have no problems you could attribute to the change, then there is no downside, at least for the materials you use.</p>

CC BY-SA 4.0
2024-07-02T11:22:44.997Z
The over/underextrusion aspect is a decent theory, but then again slicers certainly vary speed and acceleration for infill by default and those have a huge effect on extrusion as well...
Hassassin
CC BY-SA 4.0
2024-07-02T12:02:15.617Z
Fair enough regarding variation being accounted for. The only other thing I could think of is that it would affect the Z portion of the generation of 3D infill patterns like gyroid or 3D honeycomb, that you could take for granted otherwise. However, you're uncoupling shell and infill layer generation anyway by enabling this setting, so it's no different than slicing at the doubled layer height for the infill. Also, I think 3D infill is newer in slicers than infill combination, so couldn't have been a factor initially.
Tuill
CC BY-SA 4.0
2024-07-02T01:41:26.530Z
2024-07-04T00:38:59.293Z
2024-07-04T00:38:59.293Z
Tuill
<p>One default that I always change from print settings is infill combination. It combines infill layers vertically into thicker layers. That speeds up prints and probably has a positive side effect on strength. Fewer movements also means fewer occasions for something to go wrong, like knocking something loose.</p>
<p>However, it is off by default at least in Bambu Studio. Why? Is there some downside that I haven't run into?</p>

CC BY-SA 4.0
2024-07-02T06:56:27.197Z
Have you seen [this related answer](https://3dprinting.stackexchange.com/a/11542/) on "[Smaller outer layer height?](https://3dprinting.stackexchange.com/questions/11540/smaller-outer-layer-height)".
0scar
CC BY-SA 4.0
2024-07-02T11:21:29.553Z
@0scar I hadn't. That does speculate about different options, but doesn't tell us what the slicers that currently (5 years later) support this actually do.
Hassassin
CC BY-SA 4.0
2024-07-02T20:50:10.770Z
It does speculate that if the infill layer height is chosen too high w.r.t. the perimeter layer height, and the print angle is shallow, you do get voids and this potentially leads to less strong prints.
0scar
CC BY-SA 4.0
2024-07-04T12:52:08.207Z
@0scar, yes, but does that actually happen? And does it matter since we are talking about sparse infill?
Hassassin
<slicing><infill><layer-height>
Are there downsides to infill combination?
Hassassin
# Are there downsides to infill combination?

(Asked by: username_0 on 2024-06-28)

One default that I always change from print settings is infill combination. It combines infill layers vertically into thicker layers. That speeds up prints and probably has a positive side effect on strength. Fewer movements also means fewer occasions for something to go wrong, like knocking something loose.

However, it is off by default at least in Bambu Studio. Why? Is there some downside that I haven't run into?

**Tags:** slicing, infill, layer-height
> **Comments:**
> **username_1**: Have you seen [this related answer](https://3dprinting.stackexchange.com/a/11542/) on "[Smaller outer layer height?](https://3dprinting.stackexchange.com/questions/11540/smaller-outer-layer-height)".  
> **username_0**: @0scar I hadn't. That does speculate about different options, but doesn't tell us what the slicers that currently (5 years later) support this actually do.  
> **username_1**: It does speculate that if the infill layer height is chosen too high w.r.t. the perimeter layer height, and the print angle is shallow, you do get voids and this potentially leads to less strong prints.  
> **username_0**: @0scar, yes, but does that actually happen? And does it matter since we are talking about sparse infill?  

---

## 1 answers

### Answer by username_2 on 2024-07-02. Score: 1 | Accepted answer

I think a general design answer is that it's always better to have a simpler configuration as the default.

In order to perform an overall infill-combined slice the slicer would have to perform at least two additional operations: an additional slice at the multiple height (or an equivalent operation, I am not a slicer developer) for the infill, and then a merge of that with the slice for the shell at the specified layer height. This is more complicated that a single slice at the chosen layer height, ergo it is preferable to default to the simpler option.

That said, I think your own experience is the best testimonial; if you *always* change the setting and you have no problems you could attribute to the change, then there is no downside, at least for the materials you use.

> **Comments:**
> **username_0**: The over/underextrusion aspect is a decent theory, but then again slicers certainly vary speed and acceleration for infill by default and those have a huge effect on extrusion as well...  
> **username_2**: Fair enough regarding variation being accounted for. The only other thing I could think of is that it would affect the Z portion of the generation of 3D infill patterns like gyroid or 3D honeycomb, that you could take for granted otherwise. However, you're uncoupling shell and infill layer generation anyway by enabling this setting, so it's no different than slicing at the doubled layer height for the infill. Also, I think 3D infill is newer in slicers than infill combination, so couldn't have been a factor initially.  

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