Boring holes through aluminum template

using a 15" rotary table on our vertical Lagun milling machine we picked up center on the 34 1/2" bolt circle plasma cut out holes, 12 of them, and bored the holes that all were of the same diameter. This was so drill guide bushings would fit all the holes good and the same. Later we would clamp the whole 41 1/2" aluminum plate to 3" steel plates we were to drill 2 1/4" holes through.