I am preparing to start turning again after a multi decade layoff and have a question on the various types of live centers like the ones in the set in the photo. When would you use these different centers? When I was turning before, I had my Dad's old Delta lathe and all it had was a dead center that had a point surrounded by a shallow cup (cup center?) and that was pretty much all that was available. Yeah, its been that long. I now have a Nova lathe with the live center that came with it.