I went to a used sporting equipment store tonight and saw a stack of cast iron weights for weight lifting. You know the kind I'm talking about. There is a steel bar with weights on each end, held on by a collar. A person can add as much weight as he wants, up to 750 pounds or so. I've been looking for some cast iron for a chuck back plate for my new lathe and some smaller chunks for flywheels. Some of the smaller ones seem to be just the right size, so I bought several. They are quite reasonable at around 70 cents a pound. They also have some dumbbells or whatever you call them, that have a cast iron lump on each end with a cast iron shaft in between, cast as one piece. These looked like a good source also, but I didn't have an immediate need. Has anyone ever used any of these as a source of cast iron?