AIM
This is a relatively compact spool holder for large spools of up to 300 mm diameter. It can be printed on any printer with a print bed of at least 150mm x 140 mm and a print height of at least 175 mm. Looks may be deceiving a 2.3 kg spools is standing rock solid on that spool holder.
2.3 kg spools actually have mass of close to 3 kg when full. Spool holders where the spool is simply resting on its outer rim, need a lot of force exerted by the extruder, to turn the spool. To make matters worse, many spools have noticeable injection molding ridges which need even more force to overcome. As the spool progresses stepwise forward this causes an oscilating force applied on the extruder and can cause very small deformations on the printed layers which might aggravate horizontal unevenness of the printed object, especially with fast print speeds. This spool holder reduces the force needed to turn the spool to a minimum, also for full and heavy spools.
Options and Addons
This spool holder can be also used in combination with the “Drybox XL” (see here), in which it can be simply slid into. The Drybox does require however a large print bed of at least 350 mm x 350 mm.
Different versions of part B are included. They differ in which spool inner diameter they accept. The ID49mm version works universially with most common spools. The other sizes make it easier to center spools of the respective ID size.
The default spool holder can hold spools of a depth of 103 mm, an alternative, slimmer model can hold spools up to 118 mm depth.
ASSEMBLY
Press fit the two bearings into Part A (both sides). Insert the 120mm long metal tube (7.9-8mm diameter) and fixate it with 2x part D by pressing those rings on the tube on both sides, leaving the same length of tube sticking out on both sides. (There is an alternative wider part D available for slightly higher friction) For the alternative spool holder the longer Part A needs to be printed, it requires the same two bearings but a longer metal tube (139 mm).
SPOOL MOUNTING
Insert a spool into part A and then screw it in place with part B. Make sure to center the spools as good as you can. Using one of the optional part Bs can make the centering easier. Once scewed in place, simply drop in the spool into the holder.
The spool holder is designed for minimal friction. If there is a problem with unwinding due to too little friction one can add a small piece of 2 mm thick Foam tape on one or both sides, directly below the axle holder. This adds a bit of friction if needed.
BOM
The author remixed this model.
The spool holder axle is based on some design decisions from the Universal Auto-Rewind Spool but designed from ground up new. It does not include an auto-rewind function, allows for a wider spool within the same axle width. The spool holder frame is a complete custom design.