Most of the "how-to" posts have a whole series of pics showing you how to make something. This one will show you how NOT to make something.
I'm working on a piece that needed a donut chuck to finish off the bottom. It's long and tall enough I didn't want to risk using the vacuum chuck.
I started out with a round piece of plywood, 18" in diameter. Mounted that on a faceplate, drew some circles, clamped a smaller round piece of scrap particle board to the plywood, and drilled four holes. I screwed the two pieces together, and spun it up on the lathe to cut out the hole in the "donut" part of the chuck. Unfortunately, up to this point I didn't take any pics.
Anyway, here's how it looked when I was done cutting the hole out of the donut:
No problem, nice clean cut (for particle board). Unfortunately, I had to go outside to pick up the piece that I cut out of the center. It left the shop in sort of a hurry:
Only after I stopped laughing did I go in the house and get the camera.
If I'm standing at the headstock of the lathe facing the bed, that window is right behind me. But for this cut, I was standing well off to the side (at the back end of a 24" handle with another foot or so of boring bar attached to that), so I wasn't even close to the line of fire.
I guess you could say I got two donuts for the price of one. The good news is the donut chuck worked fine. The piece finished up nicely, and will be worth replacing the window for. (This one is very special...pics and more story in a few days.)