And darn, it works just like the books said it would!!! Remember---I am a veritable "new guy" when it comes to using a mill. I knew the theory of how an edge finder works, but had never used one before. Any milling I have done so far was up to scribed lines, and any holes I drilled using the mill were layed out and lightly center punched first. This time I had to put a cross hole thru the flywheel for my model steam angine for a split pin to hold it to the shaft. Of course, a round part like that is kind of a pig to lay out, so I thought "Ahah---A perfect time to try out the center/edge finder!!" I measured the flywheel thickness, divided by 2, and added 0.100 (half diameter of the edge finder probe). I set the edge finder up in the mill chuck, advanced the side to side table movement untill the edge finder contacted the part and the light in the edge finder came on. Then I lifted the head out of the way, set the table dial to zero, and advanced the table by the amount I had calculated using the feed dials on the table. Then I repeated the process in the other plane. Hot Dog!!!! It worked perfect. Then I locked both slides in place and drilled through the flywheel and crankshaft end together, and the hole was exactly where I wanted it to be. I love it every time I get to use something new, and it works exactly as I thought it should, from reading about it.---Brian