2019-01-12 Revision (r1):
This revision changes the following:
- Adds TAB & "Groove" features that provide positive alignment of the sides to the base,
- Reduces width of the base by 5mm to accommodate thinner spools.
The Prusa i3 MK2S is a great printer especially for the hobbyist or light industrial desktop user. That having been said it is a raw printer without a lot of accessories that would make it a great printer. The is the Third in a series of accessories that I designed for the i3. The others are:
The filament holder supplied with the i3 is mounted to the top printer structure and will not fit into the enclosure. Other popular spool holders likewise will not fit into the enclosure and operate satisfactorily.
This Filament Spool Holder is designed to sit on the top of the enclosure immediately above the print head path and to unspool filament through a Filament Guide to the print head.
The design incorporates large, low cost, ball bearings as resting places for the standard width 67mm spools from manufacturers such as Inland, Hatchbox, and others. Other widths can be accommodated by removing one or both sides from the base and manually positioning them on the enclosure surface as required.
The use of the large ball bearings provides a near friction free unspooling mechanism that minimizes the filament drag on the print head.
Print Sides and Base
The bearing mounts are purposely designed to be an interference fit with the bearings themselves. This eliminates the need for fasteners of an kind.
Print 4 sides and 1 base or print the assembly STL. The later contains all the needed parts in one file.
Place two Sides on a flat surface and gently tap two bearing on each side. The Inter-Race should be positioned tightly against the Outer Boss. See picture below. Make sure the outer bearing (rotating part) does not touch the sides at any point.
Place the remaining Sides over the bearings assembled above and gently tap those sides opposite the bearings with a wood mallet or equivalent until the top side is fully engaged with each bearing. Ensure the Inter-Race is tight against he Outer Boss.
Make sure the bearings turn freely.
Assemble Sides with Base
Place each side in the slots in the Base.
Center the sides on the base. Failure to do so will result in the spool "running" to one side during operation. In extreme cases the spool could fail to rotate or come off the Spool Holder all together.
Bill of Materials