---
product_id: 17976266
title: "Irwin Tools IRWIN 10239CB Unibit 2-Steps Cobalt Alloy Steel Step Drill Bit for 1/2-Inch and 3/4-Inch KO, Black"
brand: "irwin"
price: "KD 25.89"
currency: KWD
in_stock: true
reviews_count: 13
url: https://www.desertcart.com.kw/products/17976266-irwin-tools-irwin-10239cb-unibit-2-steps-cobalt-alloy-steel
store_origin: KW
region: Kuwait
---

# 2-Step Design Cobalt Alloy Steel Made in USA Irwin Tools IRWIN 10239CB Unibit 2-Steps Cobalt Alloy Steel Step Drill Bit for 1/2-Inch and 3/4-Inch KO, Black

**Brand:** irwin
**Price:** KD 25.89
**Availability:** ✅ In Stock

## Summary

> 🔧 Drill Your Way to Perfection!

## Quick Answers

- **What is this?** Irwin Tools IRWIN 10239CB Unibit 2-Steps Cobalt Alloy Steel Step Drill Bit for 1/2-Inch and 3/4-Inch KO, Black by irwin
- **How much does it cost?** KD 25.89 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.com.kw](https://www.desertcart.com.kw/products/17976266-irwin-tools-irwin-10239cb-unibit-2-steps-cobalt-alloy-steel)

## Best For

- irwin enthusiasts

## Why This Product

- Trusted irwin brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Versatile Sizing:** Easily drills through materials for 1/2-inch and 3/4-inch knockout openings.
- • **Compact Dimensions:** Package dimensions of 18.0" x 18.0" x 21.0" for easy storage.
- • **Professional Quality:** Engineered for professionals who demand reliability and precision.
- • **User-Friendly Design:** 2-step design allows for quick and efficient drilling.
- • **Precision Engineering:** Crafted from durable cobalt alloy steel for long-lasting performance.

## Overview

The Irwin Tools IRWIN 10239CB Unibit is a high-performance step drill bit made from cobalt alloy steel, designed for precision drilling of 1/2-inch and 3/4-inch knockout openings. With its user-friendly 2-step design and compact packaging, this tool is perfect for professionals seeking efficiency and reliability in their projects.

## Description

Product Description          Step Drill Bit, Material Cobalt Alloy Steel, Steam Oxide Finish, Number of Hole Sizes 2, Shank Size 7/16 In., Size Range 7/8 In. to 1-1/8 In., Sizes Included 7/8 In., 1-1/8 In., Number of Flutes 1, Shank Type Hex, Bit Length 3-1/8 In.             From the Manufacturer          Irwin Unibit Cobalt is made of high speed steel, this step drill bit will last longer in the toughest of materials. Irwin Industrial Tools 10239CB 9 2 Hole Sizes (7/8-Inch and 1-1/8-Inch )for 1/2-Inch and 3/4-Inch KO

## Features

- Country of Origin:United States
- Package length:18.0"
- Package width:18.0"
- Package height:21.0"

## Images

![Irwin Tools IRWIN 10239CB Unibit 2-Steps Cobalt Alloy Steel Step Drill Bit for 1/2-Inch and 3/4-Inch KO, Black - Image 1](https://m.media-amazon.com/images/I/31LrwAoVKnL.jpg)

## Available Options

This product comes in different **Size, Style** options.

## Customer Reviews

### ⭐⭐⭐⭐⭐ 5.0 out of 5 stars







  
  
    Perfect for drilling out GUITAR Pickup endjack
  

*by C***S on Reviewed in the United States on May 30, 2022*

I bought this after looking at countless drill bits to find the best one for drilling out the endjack for guitar pickup install.  It is a high end $3000. guitar so if I am taking a drill to it i  any way, shape, or form, it needed to be the best.  A fine guitar is made of fine woods and a fine finish so a drill bit which rips or tears at the finish or even leaves a scratch or rough spot at all is a deal breaker.  This bit was easy to use, sharp, and made a very nice clean hole for my endpin jack install.  I don't typically write reviews but wanted to write one for this bit for the benefit of other guitarists that are looking for the right drill bit for installing endpin jack for their pickup.  The pickup I installed was a K&K pure mini and the guitar is my Martin CEO-7.  I had never installed a pickup before and this 1/2 inch unibit worked perfectly.  It will get the job done neatly. Of course, make sure you also use blue painters tape on any guitar to protect during drilling.

### ⭐⭐⭐⭐⭐ 5.0 out of 5 stars







  
  
    Drilling guitar endpin jack holes.
  

*by A***N on Reviewed in the United States on June 8, 2015*

I bought this bit as part of my tool kit to drill endpin jack holes in expensive guitars to mount the endpin jacks for internal pickups. Any drill bit will make a hole, but I wanted to make sure the wood on the guitars would be in perfect condition after the hole was drilled. Causing serious damage to a $5,000 guitar can ruin a guy's day, especially if he's the owner of the guitar. Typically, if no prior hole exists, a new 1/4" hole is drilled with a sharp brad point drill bit, followed by a precision tapered reamer from a guitar luthier supply house. However, sometimes a smaller hole already exists where a strap button was screwed in or a tapered end pin was press fit into a tapered hole. Perhaps the tapered endpin was even glued into the tapered hole and can't be removed without drilling. If a strap button had been screwed in, then the screw hole could be filled and a new hole could be drilled as if none had ever existed, followed by the precision reamer to safely bring the hole to its final dimension. On the other hand, this Irwin Unibit could be used to drill a tapered hole, using the strap button screw hole as a pilot hole, followed by the precision reamer to bring the hole to its final dimension. I have used the Unibit for this exact purpose, and it worked beautifully, with no damage to the guitar. If a tapered wooden strap button has been glued in, the button can be carefully sawed off near its base, and the hole can be drilled with a brad point bit and then reamed, just like the situation where no hole ever existed. But no sawing is needed if a punch is used in the center of the wooden end pin, a 1/8" pilot hole is drilled with a normal twist metal bit or a brad point bit, and the the Unibit is used to drill through the strap button and into the guitar. Eventually, as the Unibit goes deeper, a tapered hole is formed that is larger than the strap button, and the button is drilled completely away, leaving only a nicely tapered hole for the precision reamer to follow and finish to final dimension.The Unibit can be used after drilling a pilot hole, without using the precision reamer. If that is done, it is best to stop drilling with the Unibit when it reaches the 15/32" step and then finish the hole with a standard 15/32" metal twist bit that will tend to self-center. Or, the Unibit can be used to fully penetrate the guitar base and end block, leaving a 1/2" hole that is slightly oversized for most endpin jacks, but completely usable. Alternatively, buy the 12mm Unibit, which is 15/32", and the hole will be exactly the right size. The precision reamer from the well-known guitar luthier supply house is strongly recommended, but even just the Unibit will safely do a good job. Do put blue painter's tape where the hole will be drilled to help protect the wood from damage. DON'T use the cheap tapered hand reamers, including the one from Irwin -- they do not make good, concentric holes in wood. I've tried -- and failed miserably. The cobalt Unibit is not necessary. The standard (less expensive) tool steel works well, just not as long as the cobalt. For $10 more, the cobalt seems to be the better deal if it is used often.This is a must have tool in a guitar workshop.

### ⭐⭐⭐⭐⭐ 5.0 out of 5 stars







  
  
    Irwin Tools IRWIN Step Drill Bit, 3/16-Inch to 7/8-Inch, 3/8-Inch Shank (10234)
  

*by K***8 on Reviewed in the United States on August 23, 2024*

Irwin has always been a great Step Drill when used as it should be with sheet metal.  I have used this brand for years when I was building street rods.

## Frequently Bought Together

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*Product available on Desertcart Kuwait*
*Store origin: KW*
*Last updated: 2026-01-24*