DIYbanter - View Single Post - Countersunk screw-head diameter and angle

"Jim"

wrt getting a countersunk screwhead flush with the work it's set into.

Instead of going the screwhead-diameter measurement route, there's a an old
drill press technique: Make one countersunk hole in a plate that lets the
screwheads you are using sit exactly flush with its top. Place the plate on
top of the work to be drilled. Lower a countersink bit into the plate's hole
so it fully fills it, and set the drill press depth stop. Now place the plate
under the work to be drilled, and drill the countersink in the work. This will
give you a repeat operation for making the same depth hole.
Frank Morrison