We also work with the very inventive folks at Chase Engineering....
Here's one of the handiest tools you'll ever use. These 90 degree countersinks come in 25, 12 and 6 mm cutting diameters. They are a full 100 mm long and are made from M2 tool steel. Titanium nitride coated for extra long life.
The standard 1/4" hex shank will fit quick change bit holders.
A must have for any machinist, mechanic or wood worker.
Contact McAllister's Machine Co. for pricing and availability.