John K Jordan
I decided to make some fidget spinners, mostly to see if i could.
I finished this one yesterday, my first non-test. Cocobolo, Ebony finger buttons, and three brass cylinders to add weight near the rim. I turned down the brass for a tight fit in 3/8" holes then rounded and polished the ends.
I bought a variety of bearings from Amazon to test. I made one spinner from a rectangular piece of scrap just to get experience installing a bearing. The 608 skateboard bearings are 22mm in diameter.
A 3/4" Forstner bit is too small and a 7/8 is too large. I didn't have any 22mm bits at that point so I used a 7/8 and filled that slop with epoxy. This worked OK but I'd rather have it fit better.
I tried turning a second one from Dogwood and used a 3/4" Forstner bit for the hole, enlarged with a round file. This worked well but was a pain in the neck.
Here are the first three. Note that Ebony is not necessarily a good choice for the finger buttons since it is so hard the tenon needs to be very precise to fit snugly into the center of the steel bearing. A softer wood like Cherry or Holly might be easier.
I acquired an assortment of metric Forstner bits and immediately found three different brands of 22mm bits all resulted in a hole a bit too big - about 22.4mm. I wanted a tighter fit so I finally settled on drilling a 20mm hole, mounting the blank in step jaws in a Nova chuck, then enlarging the hole to 22mm with a small scraper. This gave me the fit I wanted for the Cocobolo spinner.
The problem then was how to hold the wood blank by the central hole for turning and be able to re-register nicely when reversed. I used a jam chuck on the first two then modified some Nova pin jaws to hold a flat blank securely against a shoulder. This worked very well!
This shows the modified Nova pin jaws, the step jaws, the metric Forstner bit, and some of the bearings I've tried. Note that stock bearings need to have the grease washed out in order to spin freely.
BTW, I modified the steel Nova jaws on the wood lathe using standard woodturning tools (mostly a Thompson 1/2" scraper). I decided to machine the jaws on the wood lathe instead of the metal lathe to insure concentricity since the chuck already mated with the spindle threads. I've turned plenty of aluminum and brass on the wood lathe but this is the first time I tried steel. I can describe this further if anyone is interested.