Drill America DEWCBR1-3/16 1-3/16" X 5/16" Pilot Hole HSS Straight Shank pneumatic accessory

Purpose and user

This counterbore tool is designed for machinists and fabricators who need to enlarge existing holes to create flat-bottomed recesses for bolt heads or nuts. The two-piece construction with an interchangeable pilot allows the same cutter body to serve multiple pilot diameters, reducing tool inventory. It suits workshop tasks where spot-facing or deeper counterboring is required on ferrous and non-ferrous materials.

Pilot constraint

The cutter accepts a 5/16 inch pilot that determines the centring of the counterbore, so the pre-drilled hole must match this dimension exactly. Because the pilot is interchangeable, operators can swap pilots for different hole sizes without replacing the entire tool, but each setup is limited to the pilot fitted at that moment. The straight shank fits standard drill chucks and pneumatic drivers, though maximum speed and feed rates depend on the machine and workpiece material.

Capacity and headroom

The 1-3/16 inch cutting diameter sets the maximum recess width this tool can produce in a single pass, making it suitable for fastener seats up to that size. Deeper counterbores are possible within the flute length, but chip evacuation becomes harder as depth increases, so periodic withdrawal is advisable. The high-speed steel construction resists wear in general-purpose steel and aluminium, yet very hard alloys or high-volume production may demand carbide alternatives. California Proposition 65 warnings apply to this product.