Introduction: Wooden Ball Bearing
This instructable will show you how to make a very cool looking ball bearing out of wood. I have always been interested in ball bearings, so I decided to make one my self, and I decided that making one out of metal would be too much like bearings that you can buy, so I chose to make one out of wood.
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.
The tools that are needed to make this are:
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 a ball bearing the first thing you need are some balls, for the size that I made it took 9 wooden balls. To get these there are a couple of options, you can make them on the lathe, or you can buy them.
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.
The way I turned the races was on the faceplate, but generally with the face plate you have to put screws into the piece, this would not work for the turning, so what I did was take a piece of junk wood such as mdf about the size of the piece that you need to turn (for the outer race I used a 5 by 5 square of mdf. Attach the mdf to the face plate, then turn it to about 1/2" smaller than the piece that you need to turn. Finally take the 5 inch square that you have for the inner race, and glue it to the piece of mdf, but only on the perimeter of the mdf. This will allow you to break it off after your are done turning using a chisel or utility knife.
Both parts of the outer race, and the inner race will be turned using this procedure.
Step 4: Outter Race
For the outer race of the bearing you will need to start with a piece of flat wood that is about 5.5" by 5.5" by .75" thick. First you need to turn it into a 5" diameter circle (use the caliper to measure diameters, and be as precise as possible.). Next find the biggest drill bit that you have (less than 3.5"), I used my 2.125" forestner bit, and drill through the center of the piece of wood using the lathe. Next using the lathe tools cut the hole out to 3.5". Next you are going to cut the place where the balls will run, you will need to cut to make a hole that is 4.25" in diameter, but only goes .5" in from the front surface.
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
To turn the inner race you need to start with a piece of wood that is 3.5" by 3.5" by 1.5" thick. If you take a 2x4 and cut it to 3.5" long it is the right size (remember a 2x4 is actually 1.5" by 3.5"). Mount this to the lathe in the same way for the outer race (because this is twice as thick as the last piece you may find that you need to support the end of the piece with the tail stock), then turn it to 3" in diameter. After that mark the center of the piece, it should be .75" from either side of the piece. Then in the center cut down until the diameter of the center is 2.25", and the trench is 1" wide. Now you can drill a hole in the center of the inner race to make it look more like a bearing.
Step 6: Putting It All Together.
After all of your pieces have been cut it is time to put it all together. You want to do this on a flat clear table. Lay down one of the outer race pieces and the inner race inside it, now start putting balls in between the two.
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.