Product Description
Milwaukee Flat Boring Bit 1-3/8 in. x 6 in.
Model Number: 48-27-1371
The Milwaukee 48-27-1371 is a 1-3/8 in. x 6 in. Flat Boring Bit — a large-diameter wood boring bit for drilling clean, accurately-sized holes through framing lumber, joists, studs, plates, and wood structural members for electrical conduit penetrations, plumbing rough-in, mechanical installations, and cable management in wood-frame residential and commercial construction. The 1-3/8 in. diameter is a heavily used rough-in size specification for 1 in. EMT and IMC conduit penetrations through wood framing members where the larger conduit size requires a correspondingly larger hole diameter than flex conduit applications, for standard plumbing pipe rough-in holes where larger diameter pipe necessitates a 1-3/8 in. or larger bore diameter, and for firestop grommet and intumescent fitting installations at penetration points through fire-rated assemblies where the grommet or fitting's outer flange diameter specifies a 1-3/8 in. rough hole. Milwaukee manufactures flat boring bits from heat-treated high carbon steel with the cutting edge hardness and toughness balance needed to maintain sharpness through sustained high-volume production drilling in dimensional lumber without the rapid dulling that affects standard-quality bits in production rough-in work.
At 1-3/8 in. diameter, the flat boring bit's cutting geometry provides a meaningful advantage over alternative drilling methods for this size hole — step drill bits require multiple passes to reach 1-3/8 in. and typically produce irregular, rough-edged holes in wood, hole saws leave rough, torn-fiber hole walls and require arbor setup for each use, and larger self-feed bits at this diameter exist but have more limited application compatibility. The flat boring bit's single-pass operation, clean entry and exit surfaces, and accurate hole diameter sizing make it the standard rough-in tool for this diameter range. A self-centering tip prevents the bit from walking during hole engagement on the work surface, maintaining accurate hole position at the marked center point regardless of drilling angle — critical for maintaining dimensional accuracy in fire-rated penetration locations where the exact hole center position must align with the firestop treatment requirements specified by the building code.
Available in extended 16 in. length for applications requiring drilling through double top plates, built-up beams, and structural sections deeper than the standard 6 in. bit length can reach, and across the full Milwaukee flat boring bit diameter range from 1/4 in. through 1-1/2 in. for complete rough-in coverage.
Features
- Heat-treated high carbon steel for sharpness retention in high-volume production rough-in drilling
- 1-3/8 in. diameter for 1 in. EMT/IMC conduit, plumbing pipe, and firestop grommet installations
- Clean entry and exit faces — single-pass hole in dimensional lumber and structural members
- Self-centering tip maintains accurate hole position at any drilling angle
- Available in 16 in. extended length — full range 1/4 in. through 1-1/2 in. diameter
Specifications
- Diameter: 1-3/8 in.
- Length: 6 in.
- Material: Heat-Treated High Carbon Steel
- Available Diameters: 1/4 in. through 1-1/2 in.
- Available Lengths: 6 in. and 16 in.
Includes
- (1) Milwaukee 48-27-1371 Flat Boring Bit 1-3/8 in. x 6 in.
