Spool Hub Spacer

These are designed to thread onto the hub from [Vincent Groenhuis](https://www.thingiverse.com/VincentGroenhuis)'s [Universal Auto-Rewind Spool Holder](https://www.thingiverse.com/thing:3338467). By placing one on the hub before your spool you can keep the spool centered more easily. A second one can be used to improve the stability of wide spools, or in some cases, as a nut to hold the spool in place!

For example, the 89mm version is sized to go inside the WIDE half of a spool from ProtoPara