<p>There's no fixed maximum volumetric speed that works for everyone, there's simply too much variables to account for.
By using @Ian Williams explanation you can convert from volumetric to regular speeds but you still need to test what speed works best for your setup.</p>

<p>Just a few of the other variables affecting how fast material can come out consistently: temperature (nozzle &amp; heat brake), extruder motor power, path friction between extruder and hotend, material compressibility, fluidity and glass transition temperature, ..</p>

<p>There are interesting topics on RepRap forums, like this one: </p>

<p><a href="http://forums.reprap.org/read.php?262,654085" rel="nofollow noreferrer">http://forums.reprap.org/read.php?262,654085</a></p>

CC BY-SA 3.0
2018-04-27T18:32:46.200Z
2018-04-27T18:32:46.200Z
4levels
<p>Auto speed is calculated from maximum volumetric speed in mm<sup>3</sup> per second. If you normally print at 80 mm/s, your extrusion width is 0.5 mm and you are printing 0.2mm high layers, your volumetric speed would be 80 * 0.5 * 0.2 = 8 mm<sup>3</sup>/s, which is the volume of plastic extruded by your printer every second when printing at that speed (not accounting for any die swell).</p>

CC BY-SA 3.0
2016-01-14T20:36:23.890Z
You are right about the terms: I have updated the post to reflect this. I also found a blog post discussing the math in context of extrusion width, for those interested: http://www.extrudable.me/2013/11/03/slic3r-strange-defaults-causing-qu-bd-woes/
Tormod Haugene
CC BY-SA 3.0
2018-04-09T08:53:19.290Z
Technically not an answer... he asked for the maximum one, you gave him how to calculate the "usual one" he already tested.
FarO
CC BY-SA 3.0
2016-01-14T17:25:49.447Z
2016-01-14T23:41:13.280Z
2016-01-14T23:41:13.280Z
Ian Williams
<p>I have noticed that <a href="http://slic3r.org/" rel="noreferrer">Slic3r</a> offers a speed setting called "<a href="http://slic3r.org/blog/new-stable-1.2.9" rel="noreferrer">auto speed</a>" meant to give a constant filament pressure at the extruder, which I believe could eliminate filament grinding issues at higher printing speeds. </p>

<p>According to the tooltip in Slic3r, auto speed is calculated from two parameters:</p>

<ul>
<li>Maximum speed</li>
<li>Maximum volumetric speed</li>
</ul>

<p>Maximum speed speaks for itself, but how can I calculate the maximum volumetric speed of my print?</p>

<slic3r><print-preparation>
How can I calculate volumetric speed for Slic3r auto speed?
Tormod Haugene
# How can I calculate volumetric speed for Slic3r auto speed?

(Asked by: username_0 on 2016-01-13)

I have noticed that [Slic3r](http://slic3r.org/) offers a speed setting called "[auto speed](http://slic3r.org/blog/new-stable-1.2.9)" meant to give a constant filament pressure at the extruder, which I believe could eliminate filament grinding issues at higher printing speeds.

According to the tooltip in Slic3r, auto speed is calculated from two parameters:

* Maximum speed
* Maximum volumetric speed

Maximum speed speaks for itself, but how can I calculate the maximum volumetric speed of my print?

**Tags:** slic3r, print-preparation

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## 2 answers

### Answer by username_2 on 2016-01-14. Score: 6 | Accepted answer

Auto speed is calculated from maximum volumetric speed in mm3 per second. If you normally print at 80 mm/s, your extrusion width is 0.5 mm and you are printing 0.2mm high layers, your volumetric speed would be 80 \* 0.5 \* 0.2 = 8 mm3/s, which is the volume of plastic extruded by your printer every second when printing at that speed (not accounting for any die swell).

> **Comments:**
> **username_0**: You are right about the terms: I have updated the post to reflect this. I also found a blog post discussing the math in context of extrusion width, for those interested: http://www.extrudable.me/2013/11/03/slic3r-strange-defaults-causing-qu-bd-woes/  
> **username_3**: Technically not an answer... he asked for the maximum one, you gave him how to calculate the "usual one" he already tested.  

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### Answer by username_1 on 2018-04-27. Score: 2

There's no fixed maximum volumetric speed that works for everyone, there's simply too much variables to account for.
By using @Ian Williams explanation you can convert from volumetric to regular speeds but you still need to test what speed works best for your setup.

Just a few of the other variables affecting how fast material can come out consistently: temperature (nozzle & heat brake), extruder motor power, path friction between extruder and hotend, material compressibility, fluidity and glass transition temperature, ..

There are interesting topics on RepRap forums, like this one:

<http://forums.reprap.org/read.php?262,654085>


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