Spool Holder

Spool Holder
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I needed a spool holder for winding filament onto another spool. I could not find just what I was looking for so I have modified [Danimal_FPV's design](https://www.thingiverse.com/thing:438174),

1. lengthened the base to make it more stable,
2. added some holes in case you want to screw it down to a work-bench,
3. changed the geometry to strengthen the design
4. replaced the axel with a smoother cylinder.
5. raised the top of the forks which hold the axel, to make it less likely to jump out.

There are spindles in various sizes to allow spools with large holes to rotate smoothly.

Joiners for Multiple spool holders
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There is a joiner to link two spools in series for winding filament from one onto the other.
Also a joiner to link spools in parallel as you may need in a dry box or feeding printers with multiple extruders. The joiners may be attached to the spool holder bases with M4 x 16mm machine screws and nylock nuts (or