Neither of the 2 original nut designs for robkar's spool holder would work with the very reasonably-priced Hatchbox 1kg filament spools or 0.5kg 3D Solutech spools due to their small spool hole size. In fact, the smallest size supported by the "small" nut design by rokbar is identical to that of the larger default nut.

This improved spool retaining nut design will work with any size spool center that will fit on the holder (approx. 25mm - 68mm). Multiple retaining nuts are not required. The center of the nut is also open to allow visual feedback of where the spindle center is while tightening.

Enjoy !

-=dave

https://www.youtube.com/watch?v=1nUXAnCKdj8

Printrbot

Simple White

Doesn't Matter

No

200 microns

3% Triangular in Simplify3D