Irwin Unibit Step Drill Bit

Irwin 10231 Unibit #1 13-Step High Speed Steel Step Drill Bit

The Irwin 10231 Unibit #1 is a 13-step, high speed steel fractional step drill bit engineered to eliminate the need to change drills when boring round holes in thin materials. Sized in 1/32-inch steps from 1/8-inch through 1/2-inch, each smaller step acts as a pilot for the next size up, producing a true round hole with every pass. The patented single-flute cutting edge, paired with the SpeedPoint tip, delivers faster penetration and greater control while resisting walking as the bit steps through the workpiece, making it a go-to tool for electricians, HVAC technicians, and metalworkers.

Key Features

• Trade Size Range: 13-step Unibit design covering 1/8-inch to 1/2-inch in precise 1/32-inch increments for versatile hole sizing in a single tool.
• High Speed Steel Construction: Built from high speed steel to hold an edge through repeated use on thin-gauge stock.
• Single-Flute Cutting Edge: Irwin's patented single-flute design provides greater control as the bit progresses through each step, delivering clean, round holes.
• SpeedPoint Tip: Penetrates faster than previous Unibit designs and prevents the bit from walking off-center on the start.
• 3-Flatted Hex Shank: Secures the bit in the drill chuck and prevents slipping during operation for consistent, controlled drilling.
• Etched Diameter Markings: Drill diameters are etched directly into the flute at each step for fast, accurate size identification on the job.
• Broad Material Compatibility: Ideal for drilling thin materials including stainless steel, copper, brass, aluminum, plastic, and laminates.
• TiN-Coated Option Available: This Unibit design is also offered with a titanium nitride (TiN) coating for extended tool life in demanding applications.

Technical Specifications

• Warranty: NLW
• Battery Included: No
• Country of Origin: United States
• Packaging: 5 ea

Typical Applications

• Drilling Round Holes in Sheet Metal and Thin-Gauge Stock
• Electrical Panel, Box, and Enclosure Knockouts
• HVAC Duct and Sheet Metal Fabrication
• General Metalworking on Stainless Steel, Copper, Brass, and Aluminum
• Plastic and Laminate Panel Drilling
• Field and Shop Applications Requiring Multiple Hole Sizes from a Single Bit

Why Irwin?

Irwin builds the Unibit line around a patented single-flute cutting edge, a SpeedPoint tip, and a 3-flatted hex shank so professionals get accurate, walk-free starts and true round holes across a wide range of thin materials. Constructed from high speed steel with etched diameter markings at every step, the Irwin 10231 Unibit #1 helps electricians, HVAC technicians, and fabricators work faster by eliminating bit changes between hole sizes, while the available TiN-coated version offers extended tool life for high-volume use.