Balance weight for fidget spinner

thingiverse

The design itself is hardly worth discussing: a simple cylinder sized to fit snugly inside a 608 bearing. But the reason behind it holds some fascinating implications. I noticed my printed spinner exhibited a pronounced vibration at certain speeds. Using an ungreased ceramic bearing, it had a tendency to turn with the same side down when held vertically upright. I weighed the mass bearings with a centigram scale and discovered that the heaviest one was nearly 0.3g heavier than the lightest one, approximately 2.5% more weight. I printed three of these cylinders at different infill settings, and after some trial and error successfully achieved the combined weight of bearing and weight to within 0.02g. The vibration disappeared completely. The heaviest cylinder at 100% infill comes out to be 0.35g in PLA. The lightest one I printed with no infill and a single perimeter weighs 0.08g. If your weight difference is greater than that, you might need to exclude one.