I tried to put together the best design elements of few other spool holders published on this website and created my own universal spool holder for K8400. It can hold spools with hole diameters from 30mm to 62mm. The maximum spool height depends on the hole size - the wider holes allow to fit higher spools. With maximum hole size of 62mm, spool height can reach 120mm.
For this holder I designed my own thread with 45 degree sides that allow printing it clean without support.
The holder is attached to the original mounting piece of K8400. It uses 2 plain 608 bearings and one M8 self-locking nut (all parts of the original K8400's spool holder).
The only piece you need to purchase is M8x120mm bolt. It will replace the shorter (M8x70mm) bolt that came with the printer. New bolt can be fully threaded or, like in my case, may have only 20mm long thread at the end.
UPDATE
Check also my filament ballast that can be used with this holder http://www.thingiverse.com/thing:1887621
UPDATE 25-Dec-2017 Uploaded big-nut_rev2.stl with cutouts that reduce overall weight of the thing.
UPDATE 13-Feb-2018 Created the brake to address smoothness of this holder: https://www.thingiverse.com/thing:2792583
| big-bolt.stl | 20.7MB | |
| big-nut.stl | 21.4MB | |
| big-nut_rev2.stl | 3.9MB | |
| cover.stl | 1.4MB | |
| tube.stl | 1.3MB |
