Slic3r Manual

Once the printer is reliably producing good quality prints it may be desirable to increase the speed. Doing this provides several benefits, the most obvious of which is that the results are produced quicker, but also faster print times can be utilised in producing more layers, i.e. lower layer height, thus improving perceived print quality. An additional benefit is that a faster travel movement, between extrusions, can reduce the effects of oozing.

The best approach is to increment the various speed parameters in small steps and observe the effect each change has on print quality. Travel speed is a safe starting point, and it is not unrealistic to attain speeds of up to 250mm/s (if your printer can handle it). Adjusting the speed of perimeters, infill is available in simple mode, and the general rule is to have the perimeter go a little slower than the infill in order to reduce possible blemishes on the surface (infill can be faster because slight gaps will not matter as much).

Expert mode offers more parameters to fine tune printer speeds. Differentiation between external, small and other perimeters, infill locations, and bridges and gaps are available, as well as the ability to slow down for the first layer.

Expert mode speed options.

Expert mode speed options.

Where indicated a value can be given in percentage. This is in relation to the preceding value, e.g. 50% solid infill would be half of the value defined for infill.

A few general guidelines for each option:

Acceleration control is an advanced setting allowing acceleration settings for perimeters, infill, bridge, as well as a default setting, to be made. Deciding which values to set depends on the capabilities of the machine. Any settings within the firmware may be a good starting point.

Take into account any restrictions enforced by the firmware as many have settings for the maximum safe speed of each axis.

Speed Limits

In the Speed settings, there are two additional options for maximum print speed, Volumetric maximum and maximum.

If you found what the maximum reasonable extrusion rate your printer can do at a given temperature, you can use either one of these to limit the speeds used by Slic3r.

There are 2 experimental methods to derive the max extrusion rate:

  1. Print fast and use live tuning via M221 until you see or feel the filament slipping in the extruder (easy on a standard UM, maybe more difficult on others, and it heavily depends on the extruder mechanism how much pressure it can deliver without slipping).
  2. Perform the following extruder calibration routine (either manually in pronterface, or with some to-be-done tool): Heat the printe's hotend up a middle of the road temp (i.e. 210C for PLA), and push i.e. 20mm filament through the nozzle at a given speed (steps/sec or mm/sec), starting with i.e. 1mm/s, and observe whether or not the filament was slipping. If not, continue increasing the speed by 20%, and test again. If so, this value indicates a maximum extrusion rate for this temperature has been reached.