Metallics NHSD37E High-Speed Twist Drill Bit 37" 2-1/2" Blk Ox (1pc)

The NHSD37E is a 37 inch long high-speed twist drill bit with a 2-1/2 inch cutting diameter. The length is what makes it an installer bit: 37 inches of reach lets you drill straight through a stud bay, a sill plate, or multiple framing members in one pass without pulling the bit and re-starting the hole.

A 2-1/2 inch bore is sized for running large raceway and heavy cable bundles through wood framing. Trade conduit sizes are nominal, so 2 inch EMT or rigid has an outside diameter under 2-1/2 inches and clears a hole cut by the NHSD37E. If you are only pulling branch-circuit cable, a smaller diameter bit wastes less framing.

Different tools for different situations. A self-feed or hole saw cuts a 2-1/2 inch hole only where you can get the drill square to the face of the member, and gives you no reach past it. The NHSD37E is the choice when the hole has to travel, drilling on an angle through a top plate from below or through several members in line, because the 37 inch shank carries the cutting end well beyond the chuck.

Black oxide is a surface treatment on the high-speed steel body. It reduces friction and chip welding while drilling and slows corrosion in storage, which matters on a 37 inch bit that spends most of its life in a truck. It is a coating, not a carbide tip, so the NHSD37E is intended for wood framing rather than masonry or structural steel.

One bit per order. The NHSD37E ships as a single piece in a pouch, so if you are outfitting several crews you order one per drill rather than splitting a box.