Universal Auto-Rewind Spool Holder
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Universal Auto-Rewind Spool Holder

This video is about the Universal Auto-Rewind Spool Holder. It is used to automatically rewind filament
back on the spool after unloading. After printing the parts, the first step is to prepare the spring. Use the axle to break the top part free. Push gently on the bottom to release the bottom half.
You can also use a flat screwdriver for this. This is how the prepared spring looks like. The bearings should slide easily on the axle.
If necessary, eliminate friction using mechanical tools. Insert two bearings in the hub. Check if the hub spins easily. This one is good enough. If the bearings have high friction then you can consider
reducing friction by cleaning the bearings. Use isopropyl alcohol to dissolve old grease. Let it dry and apply light oil. It is important to have low rolling friction.
But again, it is normally not needed to de-grease new bearings. Align the dial with the clutch like this.
There are multiple alignments, but only one is correct. Turn the dial back to zero. Insert the spring, make sure that the shaft goes through the dial. Attach the hub to the clutch. Make sure that all tabs are fully inserted. Insert the axle and place the clip at the other end. Now the slipping point of the clutch can be tuned. A higher value tightens the clutch,
resulting in more torque and rewinding revolutions. Do not set the dial too high, or the clutch
may not be able to slip at all. Besides the soft spring on the right,
a stiffer version is also available. While this gives more torque,
it provides fewer rewinding revolutions. The spool can be mounted using the curved nut. The optional flat nut provides additional security. Spin the spool to check if it is properly balanced. An additional curved nut can resolve certain centering issues. However, some spools are slightly out of balance by itself. This is best remedied by placing a counterweight on the rim. The tube holder is optional and serves to better guide the filament. Pre-tension the spool by spinning it one or two turns,
before feeding the filament. Test if the clutch is able to slip
and that the spring provides enough rewinding revolutions. If the filament tube is curved,
then it should follow the curvature of the filament. A horizontally-curved tube would twist the filament,
and cause issues when rewinding. Good spool placements are behind, below and above the printer. A spiral tube gives more flexibility in spool placement. Enjoy printing and using your
Universal Auto-Rewind Spool Holder!


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