Summary

A modification of the filament pulley to accept a common 608 zz bearing, m8 bolt and 3/4 inch dowel.

Instructions

Print a top_holder (make sure you flip over before printing), bottom_holder and 2 copies of the pulley_half. Glue the pulley and holder pieces together, then put a 608zz bearing in the pulley and secure it to the holder with an m8 bolt. EDIT: the only difference between the top_holder and bottom_holder files is only the top_holder has the ring to attach to a 3/4 dowel. This means you can use 2 top_holders instead of 1 of each if you want a ring on each side.

The idea of this is the same as the source; a spool that's too large to be mounted above your printer can instead be routed though the pulley (which itself will be mounted above the printer, this version attaches to a 3/4 inch dowel). The filament can then be pulled straight down into your extruder, preventing jamming and stalling caused by feeding from the side.

I finished printing it and it works fine! You'll need a washer for each side of the bearing though (I used more because the only bolt I had was too long.). All the holes are a little bit tight but I think that's just my printer, and I like them snug anyway. Just open them up a little bit with your knife / dremel sander / whatever you want. I ended up printing the pulley in one piece with support which is why the inside looks so rough in the picture. Another thing to note is that while it fits on a dowel, that doesn't seem to be an ideal configuration. The extruder moves back and forth so the pulley should swivel a little bit too or extra filament will get fed out. I dealt with this by zip tying it to the dowel instead of mounting it right on there, this way it has a little wiggle room.

Filament pulley for 608zz