I know how to centre the rotary table on the spindle using a dti and/or wiggler/edgefinder on the central hole. But what is the best way to accurately align a work piece on the table. I need to locate
a) a circular piece to be drilled out at 120degree intervals at a radius
b) a rectangular piece to be similarly drilled as well as bored out...

Having centralised the rotary table on the spindle I don't really want to move the underlying mill table else I'll lose that registration....

I'm sure the answer is a DTI set up on the underlying mill table but I cant quite see how...