[cas3]

Yup, a quick change tool post is the way to go. Most likely, you will find you're 3 jaw chuck is not accurate, few are. Only good if you will be making the entire part, inside and outside cuts, then it doesnt matter. The 4 jaw chuck is as accurate as you want to make it, by perfect adjustment. I mostly only use the 4, and have a dial indicator mounted on a magnet that I slam up on the tool post to dial in the part. Seems a hassle at first, but you get good at it