On my cast iron table it just sets in the cutout. I left it just a touch larger so it wouldn't move around in the cutout. On the aluminum one on 3 spots on the edge it had a small area peened to make a tighter fit
I make my own for the Delta and Shopsmith as the aluminum ones can be a bit hard to find at times. I am not sure you need a template to setup the circle cutter, but I seem to have a template for about everything I do.
ldh