I decided to make a shaft with bearings after my first tests trying to make a homemade disc sander with the drill. Anyway, I realized there that it is very difficult to get the sanding disc to rotate flat, without wobbling. This is mainly due to the fact that the drill chuck shaft does not rotate fixed, but has a small clearance that makes it give way to where you press the sanding disc (something to keep in mind in our home machines powered by a drill). The result is that the disc was impossible for me to rectify. You can see the video at the end of this post.
To make this shaft with bearings, I will a piece of steel pipe. And at the ends of this pipe I will fit two ball bearings. The bearings are going to get very tight around this steel pipe, but that's what I have.
I would give you the dimensions, but it is best to find a threaded rod, tubes and bearings that fit the best possible. Without focusing on a specific measure. In my case, the important thing was that the distance between one bearing and the other was not too great, so that I didn't have to make a very wide support. But for others homemade machines I wanted to do, I still need more distance between bearings. Or also a thicker threaded rod.
I also need a piece of copper pipe that fits perfectly, like a sleeve, around the steel pipe that will work as an axis. And the copper pipe plus the two bearings should measure the same as the piece of steel pipe.
So once I have cut the pieces of the tubes and after cleaning the burrs with a fine metal file, I have to put a threaded rod inside the steel tube. So I screw two nuts, one against the other, on one end of the rod. I press the piece of tube into the vice, and with the wrench around one of the nuts, I turn the rod so that it threads into the tube. It fits very tightly, since it has to "carve" the thread as it enters.
And now I have to fit the ends of the steel pipe inside the bearings. So I put a large washer over one of the holes of my workbench and I put a bearing on it. I place the steel pipe on the hole of the bearing, and trying to keep it vertical, I hit it so that it enters the hole little by little.
I cooled in the fridge the steel pipe that will serve as the axis, but it still fits very tightly. Although in the end I managed to get it in.
Now I put the piece of copper pipe, like a sleeve, around the steel shaft. And I fit the second bearing in the same way that I put the first. Thus the copper sleeve will maintain the separation between both bearings.
To prevent the bearings from slipping out, I put a small washer and a nut on each end. And with a pair of wrenches, I tighten the nuts against the washers. This way the washers press only the inner ring of the bearings, but the outer ring will continue to rotate freely. And inside the shaft, the inner ring of each bearing is pressed against the copper sleeve.
To prevent the nuts from loosening, I insert a pair of self-locking nuts at each end. And so I have this shaft with bearings ready, and I can use it in some of my homemade woodworking machines. But as I already mentioned, in this case it is to make a drill powered homemade disc sander.
And next we can see the video in which I talk about the problems about making a disc sander with the disc shaft connected directly to the drill chuck.