I am working on a project where I have to cut 100's of slightly over .5" holes .6" deep, then cut a .25 hole an additional .030 into the bottom of it. Is there a 1/4" bit I can use that will drill both cut the bigger hole, and the smaller hole inside of it but won't leave the rounded over hump in the middle since it's not traveling? This is hardwood by the way (white oak).