This bearing consists of 3 parts, the inner race, the outer race, and the balls. Most ball bearings have what is called a cage that is pressed in to hold the balls in, but I could not make that so I made this with the outer race as 2 parts glued together.
Step 1: Tools and Materials Required.
Wood lathe with a faceplate (A metal lathe would work very well, but be careful turning wood on a metal lathe, because if you leave saw dust on the lathe it could rust)
Drill bit assortment
Wood Chisel (Or utility knife)
2 5.5 inch squares of 3/4" thick wood (I used pine because that is what I had, but hardwood would be better, but anything you can turn on your lathe is fine) this is going to be the outer race
1 3" square of 1.5" thick wood (I cut this out of a 2x4) this will be the inner race
Material for 9 wooden spheres (see next step)
Super glue/ Wood glue
Step 2: Balls
To make them:
There is a process that you can do on the lathe to make a pretty good wooden sphere, I found out how to do this from this site http://www.woodturners.org/tech_tips/frame_1.htm.
I tried to make the balls on my lathe, but that takes a lot of time, it took me several hours to get the first one correct, then about an hour and a half for each of the next ones (took so long because you need to get them to the exact same size) so for 9 balls you are looking at more than 12 hours.
They are cheap, I got mine from Michael's, and it was less than $5 for 16 of them, most any craft store should have them. The biggest downside to this is that you can't find them in any other wood than pine, and hardwood would be better, but the pine ones work.
Step 3: How to Turn the Races.
Both parts of the outer race, and the inner race will be turned using this procedure.
Step 4: Outter Race
After you make that, you need another one exactly the same as it. After you have 2 identical outer race halves it is time to cut the inner race.
Step 5: Inner Race
Step 6: Putting It All Together.
If you start to put the balls in and after a while you find that it is too tight and you can't fit any more then you are likely slightly off on one of your dimetions. If you have a chuck that can handle the piece then you can put it back on the lathe and modify it, but if you do not you either need to make a new piece or carefully sand it with a dremel (if you use a dremel you will likely have a spot where the bearing doesn't turn uniformly.)
After you have all of the balls that will fit (for mine it was 9) put the second part of the outer race on top, line it up to the other piece of the outer race, then glue them together. I used superglue because i was impatiant, but wood glue would be better. Also use a sparing amount of glue because you do not want glue on one of the balls.
After the glue dries sand the outside as necessary, and now you have a wooden ball bearing.