Newbie ?: How do I find the center of a metal disc to drill a center hole

[HMF]

In order to drill an accurate center hole on a milling machine, how would you locate the center of a round metal disc (machinist combination square?) so that the center hole is as accurate as possible?

Thanks,

Nelson

 

[Tony Wells]

Mount a test indicator in the spindle so the edge of the disk can be swept in, and you are in the center. Part of the difficulty would be in avoiding the clamps, if used, but in a chuck of an indexer it is simple. If there are clamps in the way, the spindle is used to raise and lower the indicator to bypass them during the sweep.

 

[Tony Wells]

Yeah, but Randy, you gave a more thorough explanation of various approaches. It's always good to have options. AND pictures!