Fidget Spinner Gyroscope 12 1/2" inch balls

thingiverse

Human: 75 mm dia circular spinner with twelve holes at the rim for 1/2" chrome steel ball bearings (slingshot ammo). Standard 608 skate bearing (8x22x7mm) needs to be scaled up for a tight press fit around the balls. Any adhesive will throw off the balance. You might even try using 50 caliber lead balls used in muzzleloaders. Scale Bearing_Button_v1.stl to 99% so you don't have to force it into place. It's tough to remove the grips from the bearing when printed full size. Try printing with three perimeters, a 20% hex infill, and zero top and bottom layers. This will expose the hex infill (as in the photo), which you use a soda straw to blow against to accelerate the spin. Remember, human power only! Don't even think about using an air compressor! Ask your science teacher about centrifugal force. Using a kerosene-lubed Yellow Jacket ceramic bearing, and with all twelve 1/2" balls installed, I got a five and a half minute spin. This thing was made online in Tinkercad. Edit it at https://www.tinkercad.com/things/kOjbeE1PfJq