Slic3r Acceleration control

Hey all,

Can anyone give more info on the Acceleration control (advanced) options in slic3r’s speed panel?

Does this override the firmware? Ought I move it above 2000 mm/s2?

It overrides the firmware. I’d be interested in hearing your results. :slight_smile:

I doubt it will make it accelerate faster than the firmware’s limits…but it can make it go slower I would imagine (just like max speed settings).

I have not messed with it at all…the effort to set it up correctly just doesn’t seem worth the small gain IMO. But go for it is you have the inkling.

Actually, I think it will override the firmware’s settings, even if faster.

Well i doubled perimeters to 4000m/s/s and it was sailing until it skipped steps (i think) on the y axis started printing 5 mm off on the y.

Can anyone say a bit more about this? What is the acceleration, and how come the values are so high i.e. 2000mm/s
and so on…

When you put an acceleration value foo mm/s^2 into slic3r, it will put this into the output file right before the designated print feature (infill, perimeters, etc):

M204 Sfoo

This will override the firmware setting, which can be found in the mechanical settings section of configuration.h of the firmware. It looks like this:

#define DEFAULT_ACCELERATION          500    // X, Y, Z and E max acceleration in mm/s^2 for printing moves

(you can find the firmware here: http://devel.lulzbot.com/TAZ/Guava/software/current/Marlin/Marlin/Configuration.h )

However, it will not change the jerk setting. Jerk is http://en.wikipedia.org/wiki/Jerk_(physics), or the rate of change of the acceleration. The line in the firmware that sets the maximum jerk looks like this:

#define DEFAULT_XYJERK                8.0    // (mm/sec)

and can be changed from 8 mm/s^3 to something else by navigating through the LCD like control>motion>Vxy-jerk and then changing it (don’t forget to use “store memory” if you would like to make the changes persist through a power cycle). Or by running

M205 Xfoo

from the pronterface terminal.

Jerk is the rate of change of the force applied to the carriage (since F=ma, force and acceleration are proportional). Even if you crank your speed and acceleration settings to over 9000, a lower jerk setting will correspond with a longer overall print time, because it is limiting the rate of change of the acceleration.

After setting the acceleration to 5000-8000 mm/s^2 and skipping y steps (1-2 mm near the 5mm z height), support told me they use max 1800 and low 1300.

I had set some to 200 and noticed it crawling, after reading 500 is the default that helps a lot.

Was trying to set infill only to 1800 and slic3r kept erroring, it doesn’t like values of 0 for the others when one is set up.