### How can I calculate volumetric speed for Slic3r auto speed?

• I have noticed that Slic3r offers a speed setting called "auto speed" 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?

• 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).

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/

Technically not an answer... he asked for the maximum one, you gave him how to calculate the "usual one" he already tested.