I made this tool to use in conjunction with Jeff's "drill bit hollower" when turning boxes. It uses standard or carbide router bits rather than the hss square bits. It does a great job of eliminating all the tear out on the end grain box floor and walls. Pictured with a core box bit installed that has a radiused profile and a beading veining/bit below. I've found it a joy to use and flexiable cutting angles just by rotating the amount of exposed cutting edge..Bill...