7/31/22: I redesigned the Spool Holder slightly. On very tall parts (>7") the print head hit the front of the flange the wraps in front of the cross bracket of the printer. This dislodged it and dumped the spool off. So I simply shortened flange to create clearance. I apologize to anyone that made the previous part!

_____________________________________________________________________________________________________________

This Filament Spool Holder replaces the cantilever spool holder supplied with the Prusa i3MH3 printer. I frankly got tired of knocking it loose when I changed spools. It slides down over the top bracket and the spool rests on four ball bearings. The Mount is printed as a single part without supports. I used rotated squares and hex openings for horizontal holes so they print clean. The Bearing Posts probably could be printed without supports, but I used supports to keep the hex pocket clean.

This is sized for standard 1 Kg spools. That's all I use. I do NOT know if it will work with 2 Kg spools. I have used this with spools from Hatchbox, Paramount3D and Overture (cardboard spool).

I redesigned the 

Please note that the hole in the front of the mount is NOT a filament guide. It is just used to hold the filament when changing spools so the filament doesn't wind back up on the spool. I integrated one of my other designs here (https://www.printables.com/model/220526-filament-holder).

I spent a little more money on the bearings (ABEC 9) to ensure they work correctly in the long-term. Because they sit above the print bed, you need to ensure they are not overpacked with grease. They also need to spin very freely (think of a bearing that would be in a fidget spinner!).

The screws that hold the Bearing Posts is inserted from the outside of the Mount and the nuts are placed inside the Bearing Posts. You will be able to tighten these down very tight without impacting the rotation of the bearings because of the raised surfaces on the inside rail of the Mount.

I needed to sand down the bearing surface on the Bearing Posts to get the bearings to slide on. I wanted them pretty tight, so I didn't resize them. Mostly just smoothed out the ridges on the surface.

This design was inspired by the design by Devilscave: https://www.printables.com/model/20226-ultimate-spool-holder-v3-for-prusa-mk3s-inspired-b%2Fcomments

Hardware Parts List:

1. Ball Bearings: Size 608ZZ (8mm ID x 22 mm OD x 7 mm wide)
   1. I used “Yellow Jacket Premium Skateboard Bearings, Pro Longboard Bearings, 608, ABEC (Pack of 8)” from Amazon.com
2. Fasteners:
   1. Four #6-32 x .75" long Pan Head Screws
   2. Four #6-32 Nyloc Nuts

Print Settings:

• PETG (PLA would probably be OK, but it sits above the heated print bed and I didn't want to worry about the long-term effects!)
• 0.2mm Layer height
• 4 perimeters (for added strength)
• 30% Gyroid Infill (I selected Gyroid because it looks cool and is fun to say!)
• No supports on the Mount, but used supports on the Posts
• The Mount took 9 hours to print and the four posts took 45 minutes.