Milwaukee 48-20-4385 Spline Drill Bit 1-1/8 in 4-cutter

Product Description

The MILWAUKEE 48-20-4385 is a spline-shank rotary hammer drill bit built for drilling through brick, block, concrete, and reinforced concrete. The bit uses a 4-cutter, 4 x 90-degree tip geometry designed to prevent lock-up when the cutting edge contacts rebar. A patented rebar chamfer design extends service life by reducing chipping and deformation at the tip. The high-volume flute clears debris quickly to maintain drilling speed and reduce heat buildup. At 1-1/8 inches in diameter with an overall length of 16 inches and a drilling depth of 11 inches, this bit is suited for commercial and residential masonry applications where productivity and durability are priorities.

This bit is designed for use with spline-drive rotary hammer drills in applications requiring larger-diameter holes in masonry and concrete. Typical use cases include anchor setting, conduit penetrations, structural concrete drilling, and block wall penetrations. The 4-cutter geometry and rebar chamfer make it particularly well-suited for reinforced concrete slabs and walls where rebar contact is likely. It is installed and used by electricians, plumbers, HVAC technicians, and general contractors working in concrete-heavy environments.

Key Features

• 4-cutter, 4 x 90-degree tip geometry prevents lock-up on rebar contact
• Patented rebar chamfers increase tip durability in reinforced concrete
• High-volume flute design accelerates debris removal and reduces heat
• 1-1/8 inch diameter with 11-inch drilling depth and 16-inch overall length
• Spline shank for use with spline-drive rotary hammer tools

Compatibility

Designed for use with spline-drive rotary hammer drills. Suitable for drilling into brick, block, standard concrete, and reinforced concrete.

Installation Notes

Installation requires a spline-drive rotary hammer drill; verify the tool chuck accepts spline-shank bits before use. Always wear appropriate PPE including eye protection and hearing protection when operating a rotary hammer. Inspect the bit for tip damage or shank wear before each use and replace if deformation is present. Follow applicable site safety and OSHA guidelines when drilling into structural concrete or masonry.

Technical Specifications

• Shank Type: Spline
• Cutting Diameter: 1-1/8 inches
• Overall Length: 16 inches
• Drilling Depth: 11 inches
• Cutter Configuration: 4-cutter, 4 x 90-degree tip geometry
• Application: Brick, block, concrete, reinforced concrete
• Weight: 2.02 pounds
• UOM: Each

Standard Information

• Brand: MILWAUKEE
• Manufacturer Part Number: 48-20-4385