Make a jig for each size disc.
Have a top plate of steel (don’t use tool steel) with your desired
hole size. Solder a base metal sheet( a little thinner than your
stock) with the disc size cut out centered around the hole in steel.
To use…slip a disc in cutout, invert and press against a wood
block, drill thru hole in steel.
You would have to do the layout for each size but you’d only need to
do it once. A steel plate will give longer hole accuracy-life than
softer metals. Use base metal for cutout plate because its easy to
Layout can be done with dividers. Starrett makes a nice small
combination square. See page 184 In the Rio Grande tool book. This is
a worthwhile tool to have around.
One easy way to make this jig… make your round cutout for nice
tight but removable fit, a notch would be handy. Take a disc and
using the combo square find and drill center. Drill steel plate. put
steel and base metal plate together with a disc in place. Run a drill
rod through hole in both disc and steel, it will automatically line
up correctly. Solder plates together with drill rod in place. It
doesn’t have to be beautiful looking, its beauty is its ease of
manufacture and use. Do this carefully and you will be able to knock
out scores of identical, centered holes in no time.