Simple, fast-printing hub for spools with a 1.5" ID. Fits up to a 5/16" center rod. Beveled inside edges to make it easier to fit the rod through while half asleep. NOTE: This is not a 'friction fit' hub, it's meant to be held in place with a dab of superglue. If you want friction fit, scale it up by a few percent. Use at your own risk - I am not responsible for any injury or damage, etc. I print at 0.2mm layer height, 20% infill. This is always the first thing I print with a new spool both for its immediate usefulness with that spool, as well as an indicator of how well that filament prints before going on to more complicated prints.