How to center a piece of work on a rotary table?

[ScrapMetal]

It's been bit slow in here lately and as soon as the raw materials show up I'm going to need this information.  

Centering the rotary table on my mill is simple using my DRO and Haimer.  Getting the work piece in the proper position on the rotary table becomes a bit of a problem though. 

I will need to "center" a portion of an oddly shaped piece of work on the rotary table in order to round off an edge that is an arc and in another operation cut a section out of it in a circular arc.

Anyone have effective methods for centering/positioning work on rotary tables?

Thanks,

-Ron