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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.
Manufacturer Resources
Product Specs
- Department:
- Electrical
- Product Type:
- Step Drill Bit
- list_batch:
- IRW-20260923
- Product Subgroup:
- Hole Saws & Bits
- Country Of Origin:
- United States
- Product Group:
- Power Tools & Accessories
- Power Source:
- NON-ENERGY USING
Irwin 10231 – Frequently Asked Questions
1) What is the difference between the Irwin Unibit #1 and the #2 if they both stop at 1/2 inch?
The starting diameter. The #1 begins at 1/8 inch and works up to 1/2 inch in 1/32 inch increments across 13 steps, so it covers the small pilot and screw-size holes too. The #2 starts at 3/16 inch and ends at the same 1/2 inch, so you lose the smallest steps. Pick the #1 if you drill small holes in sheet stock as well as connector holes.
2) Can I use an Irwin Unibit step drill on stainless steel?
Yes. The Unibit is high speed steel and rated for thin materials including stainless steel, copper, brass, aluminum, plastic and laminates. It is built for thin-gauge stock, so it is not the tool for thick plate where the step geometry cannot clear the full depth of a step.
3) Does the Irwin Unibit walk when starting a hole in sheet metal without a center punch?
The SpeedPoint tip is designed to resist walking off center on the start and to penetrate faster than earlier Unibit tips. The single-flute cutting edge also gives more control as the bit progresses through each step. Center punching is still good practice on slick stainless, but the tip is built for unpunched starts.
4) How do I know what size hole I am at partway through drilling with a Unibit?
The diameters are etched into the flute at each step, so you read the size off the bit as you go. Each smaller step also acts as a pilot for the next one up, which keeps the hole true and round instead of triangulating like a twist bit in sheet metal.
5) Are Irwin Unibit step drill bits sold individually or in a multipack?
Packaging is 5 each, so the Unibit comes as a 5-piece pack of the size you select rather than a single bit. That suits a shop or a crew standardizing on one hole size range. Country of origin is the United States.
6) Is there a longer-lasting coated version of the Irwin Unibit for high-volume drilling?
Yes, the same Unibit design is also made with a titanium nitride (TiN) coating for extended tool life in demanding, high-volume work. The bits offered here (#1, #2 and #4) are the uncoated high speed steel version.
How fast can I get the Irwin 10231 delivered?
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Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit,
reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Irwin 10231 come with a warranty?
Absolutely. The Irwin 10231 is backed by a manufacturer’s warranty.
For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Irwin 10231?
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