Where your spools are located can make the difference between trouble and smooth operation of the printer. It is also often desirable to reduce the footprint of the printer as much as possible. Here are some pointers to where it is best to keep the spool and it's holders according to our experience.
MK2/S, MK2.5/S and MK3/S:
Ideal location of the spool for the MK2/S and MK3/S is using the supplied spool-holder mounted on top of the printer. The frame will support several spools with ease.
The MMU2S is supplied with different spool-holders than the MK2/S and MK3/S. It is a continuation of the spool holder design used for the first MMU. It has been tested through thousands of hours of printing and was proven functional.
When the MMU unit is changing the filament, it unloads it from the orange/white PTFE tube situated between the extruder and the MMU unit, meaning that roughly 450 mm of filament is retracted. That is why it is recommended to arrange the spool holders at about 400 mm behind the printer (green line).
Our solution for dealing with retracted filament is a device called the filament buffer. The filament string creates a loop inside in order to prevent tangling. The setup requires a space of at least 70 × 100 cm.
Ideal location for the spool with the Prusa MINI is right next to the LCD-screen. This creates the smallest footprint possible. If you have the space is also possible to have it sideways next to the printer, pointing towards the printer. Most important is that the filament does not bend in an acute angle.