Having built a lathe, I needed a project to try it out. I figured turning a ball would be a fun challenge. I started with a thick piece of maple and glued some pieces of mahogany on it to get more thickness and some contrast.
I marked a circle on it to figure out how much excess to cut off before putting it on the lathe.
Cutting away as much as I could with the bandsaw. The more I cut away, the less there is to get good support on the table, so I couldn't cut away as much as I would have liked to.
Workpiece mounted on the lathe. I added a drop of oil to the "dead center" so it could turn more easily on the point on the fixed shaft.
Spinning up the blank, running at about 1200 rpm. No pieces flying. Good.
Roughing it out until the main part is a cylindrical shape
A nice aspect of this lathe is, with the spinning part of the headstock made of wooden pulleys and just a 12 mm shaft, it's very light. So with this workpiece, if I get my chisel caught in it, it just comes to a stop immediately instead of taking a huge chunk out.
But not everything is perfect about my homemade lathe. There isn't a good way to tighten the tailstock onto the workpiece. With the tailstock shaft only held by friction, there's the possibility that it might slide back suddenly, releasing the workpiece. I'll improve that later. (Update: fixed that and a few other things)
I made an arc shaped guide to check the size and curvature. Here I'm checking the diameter. It's almost down to the right size.
Width wise, I have enough left in the profile.
With the main diameter turned to the right size, and turning it so the guide fits snugly around the curve, I should have a sphere.
Checking it at a few different angles.
I was confident enough in the shape to proceed with sanding it smooth.
After that, I used a parting tool to turn the ends down to about 1 cm.
Then I cut those ends flush with a hand saw....
... and sanded it round on my strip sander
The resulting ball was fun to roll around. It looked perfectly round.
But checking it with my guide, it is slightly flat on one side. Oh well. Wouldn't have guessed that by just looking at it. I will have to be more careful next time.