Finding center...

[Wreck™Wreck]

What if the edge is not straight? Would the edge finder work when it is facing a curved edge like a round machined wheel? I have tried using an edge finder intentionally away from the center line and it sure found the edge but not on the center line. I hope I am explaining this properly.

All that you need is to find a reference surface on the form that you have to machine so that you may move to the next feature, it may often be beneficial to produce a reference that will be cut away after the part is finished.

In this drawing a flat is first milled in the round stock, every mill OP after turning uses this reference surface, after the mill work is done it is then parted off in the lathe.
If one had to make thousands of these parts per month this would not be the way to do it.