Best Drill Bits for Hardened Steel - Boom & Bucket

Drilling through hardened steel can be one of the most challenging tasks in metalworking, whether you're a blacksmith, swordsmith, knife maker, or simply working on tough projects. To make the job easier and avoid costly mistakes, it's crucial to have the right drill bits and the correct technique. Based on years of experience and expert recommendations, here’s a comprehensive guide to the best drill bits for hardened steel, along with tips to ensure success.

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1. Bosch Cobalt 42 Bits

Affordable and Effective Bosch Cobalt 42 bits are often considered the go-to option for those who need a budget-friendly drill bit that can handle hardened steel. At around $5 for a 1/4-inch bit, they offer great performance without breaking the bank. While these bits are durable, they do tend to wear out faster if used on work-hardened steel or without cutting fluid.

2. Drill America Carbide Bits

High Performance at a Higher Price If you’re looking for a more durable option, the Drill America Carbide bits are an excellent choice. Priced between $15-20 per bit, they offer impressive performance for drilling through tougher materials. Carbide bits last longer than cobalt, but they can be brittle if not handled carefully. The key is to avoid chipping the cutting edges, which can happen quickly if you’re not cautious.

3. Drill Doctor (Bit Sharpener)

Maintain Sharpness for Longevity One of the best investments you can make when drilling through hardened steel is a quality bit sharpener. The Drill Doctor is a top choice for many professionals. Using diamond stones, this tool can keep your cobalt and carbide bits sharp for years. It’s especially useful for sharpening expensive carbide bits that you want to preserve, even if they’ve been chipped.

4. Cobalt Drill Bits

Tough and Reliable Cobalt drill bits are well-known for their ability to handle high temperatures and wear, making them perfect for drilling through hardened steel. These bits work best at slower speeds (around 500- RPM) and require generous amounts of cutting fluid to maintain sharpness and prevent overheating. Cobalt bits are a great balance between cost and performance, making them a staple in many workshops.

5. Carbide End Mills

Ideal for Enlarging Holes If you need to enlarge holes in hardened steel, carbide end mills are a great option. These bits are designed specifically for hard materials and can handle tough tasks. However, they can be expensive and prone to breaking if used improperly. If you decide to go with carbide end mills, be prepared to handle the pressure and pay attention to your technique.

6. Speed and Feed Charts

Optimize Your Drilling Drilling through hardened steel requires careful attention to the speed and pressure applied. Speed and feed charts are invaluable resources that help you choose the right RPMs based on the size of your bit and the material you're working with. For hardened steel, it’s important to apply significant pressure—enough to ensure the bit bites into the material. Insufficient pressure will cause the bit to skate, generating heat that can dull the bit quickly.

7. Cutting Fluids

Cool Down and Protect Your Bits Always use cutting fluid when drilling through hardened steel. This helps keep the bit cool, reduces friction, and prolongs the life of your drill bits. There are many types of cutting fluids available, such as sulfurized dark cutting oil or coolant oils like Trim-Sol. Make sure to apply it generously to prevent the bit from overheating and becoming dull.

8. Single Flute Carbide Drill Bits

Perfect for Hard Materials For especially tough materials, single flute carbide drill bits are an excellent choice. These bits allow for higher RPMs and are often run dry (without lubrication), although using cutting fluids can still improve the drilling process. Carbide bits provide excellent precision and longevity, but be careful with their brittle nature.

9. DeWalt Pilot Point Cobalt Bits

Versatile and Durable DeWalt’s Pilot Point Cobalt bits are versatile and durable, making them a great option for various metalworking applications, including drilling through hardened steel. The key to using these bits effectively is to avoid wobbling—if the drill wobbles, the bit could snap under pressure. Keep the material steady and ensure the drill is properly aligned.

10. Tile/Porcelain Drill Bits

An Alternative for Tough Steel Some users have found success using tile or porcelain drill bits for hardened steel, especially when traditional bits don’t work. These bits may provide better luck in challenging situations, although they aren’t typically the first choice for hardened steel.

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11. Use of Vise

Stabilize Your Material When drilling through hardened steel, always secure your material in a vise. Attempting to hold the steel by hand can lead to unstable drilling, causing wobbling and increasing the risk of breaking your bits. If you don’t have a portable vise, clamping your workpiece to a solid surface will work as well.

12. Lubricants like TapMagic or WD-40

Essential for Smooth Drilling Lubricants such as TapMagic or WD-40 are essential when drilling through hardened steel. Not only do they reduce friction, but they also help to transfer heat, which is crucial for preventing bit wear. Use plenty of lubricant to ensure a smooth drilling process, especially when working with tougher materials.

Final Thoughts

When it comes to drilling through tough and sturdy materials like metal, having the right drill bits is crucial. Whether you’re a professional tradesperson or a DIY enthusiast, selecting the best drill bits for metal can make all the difference in the success of your project. In this comprehensive guide, we will explore the top options available, including cobalt drill bits and heavy-duty variants designed for hardened steel.

Understanding the Basics

Before we dive into the specific types of drill bits, it’s essential to understand the key factors that make a drill bit suitable for metalworking.

1. Material: Metal drill bits are typically made from high-speed steel (HSS) or cobalt. HSS drill bits are more affordable and work well with softer metals, while cobalt drill bits are the top choice for drilling into hard metals like stainless steel and titanium.
2. Coating: Many metal drill bits come with specialized coatings, such as titanium nitride (TiN) or black oxide. These coatings reduce friction, increase durability, and enhance heat resistance.
3. Point Angle: The point angle of the drill bit affects its cutting efficiency. A 135-degree split point is common for metal drilling as it provides better self-centering and reduces the risk of “walking” when starting a hole.

Now, let’s explore the best drill bits for metal, including cobalt drill bits and heavy-duty options for hardened steel.

Cobalt Drill Bits for Metal

Cobalt drill bits are the go-to choice when you need to tackle tough metal surfaces. Here are some reasons why cobalt drill bits stand out:

• Hardness: Cobalt is extremely hard, which makes these drill bits perfect for drilling through hardened steel, stainless steel, and other robust metals.
• Heat Resistance: Cobalt bits can handle high temperatures without losing their cutting edge. This feature is vital when drilling through metals that generate a lot of heat during the process.
• Longevity: Cobalt drill bits are known for their durability and extended lifespan compared to standard HSS bits.

Drill Bits for Hardened Steel

When you’re dealing with hardened steel, ordinary drill bits just won’t cut it. You need drill bits designed specifically for this challenging material. Here’s what to look for:

• Carbide-Tipped Bits: Carbide-tipped drill bits are ideal for hardened steel. The carbide tip can withstand the extreme hardness of the steel and maintain its sharpness.
• Flute Design: Look for drill bits with a parabolic flute design. This helps with chip removal and reduces heat buildup, preventing bit damage.
• Split Point: As mentioned earlier, a 135-degree split point is crucial for accurate drilling in hardened steel.

Heavy Duty Drill Bits for Metal

For heavy-duty metalworking tasks, such as drilling into thick metal plates or structural steel, you’ll need heavy-duty drill bits that can handle the load. Here’s what sets them apart:

• Sturdy Construction: These bits are often constructed with a thicker shank and a reinforced core to withstand heavy drilling.
• Increased Flute Length: Longer flutes enable deeper drilling without frequent bit changes.
• Advanced Coatings: Heavy-duty bits may come with advanced coatings for added heat resistance and longevity.

Selecting the right drill bits for metal is essential for achieving precise and efficient results in your metalworking projects. Whether you opt for cobalt drill bits, specialized bits for hardened steel, or heavy-duty variants, always prioritize quality and compatibility with your specific drilling needs. With the best drill bits at your disposal, you’ll be well-equipped to tackle any metal drilling task that comes your way.

Contact us to discuss your requirements of drill bits for drilling steel. Our experienced sales team can help you identify the options that best suit your needs.