The Craftsman lathes never used a cam lock chuck. They were all threaded spindles. The Craftsman 6" swing baby lathes used 1"-8 or 1"-10 threaded spindles, depending on when it was made. The larger 10"/12" swing Atlas/Craftsman lathes all used a 1 1/2"-8 threaded spindle noses. There are tons of options for new and used three and four jaw chucks out there for very reasonable prices. A three jaw is quicker, but less precise, while a four jaw can be dialed in to eliminate all runout, but takes a little effort. Nothing wrong with a threaded spindle but you need to be careful if you are plugging reverse or the chuck can unthread itself and end up in your lap.