Tank and Washer Cutter

Tank and Washer Cutters are traditionally used by Plumbers to drill large holes in thin sheet materials - sheet metal storage tanks for example (their use for this is now largely superseded by Holesaws).

They comprise a pilot drill gripped in an Arbor around which an adjustable cutter is rotated to cut the hole. If two cutters are fitted to the Arbor, washers can be cut out. Arbors are available with a Square Tapered Shank to fit a Carpenter's Brace but Hexagonal Shanks and Parallel Shanks (with or without flats) are also available for use in Power Drills - but use at slow speed!

They are sometimes also referred to as a Trepanning Tool.