I keep thinking back to a demonstration that our club had. The turner mounted a piece between centers on a DVR. He was unfamiliar with the lathe, and turned it on. It had been left at high speed. He hit the off button. Then he fired it up again, and hit the ramp down speed button. This lathe is very slow to respond, and the piece came off the lathe. It went up, and there were no injuries. Yes, he didn't check the speed first, but this has happened to all of us at one time or another. What I am wondering, is would it be possible to make a lathe which when you turn it off, the rpm reverts to 0 every time?
This could be a big safety factor, especially in school/class situations where you never know who was on the lathe before you. The dial knob would not be a speed indicator, but for me that would not be a problem as I have never had one on any of my lathes. It might be necessary to add an electronic read out to every lathe, but it seems that is already becoming a standard in the industry. Yes, you would have to twist the knob each time, but that is only a second or two. We almost all talk about finding thee right speed for turning by saying, "I just turn the speed up till it starts to wobble, then back it down a bit.