Best Drill Bits for Drilling Through Steel: Cobalt and HSS Options Compared
Selecting the right drill bit for metalwork requires balancing material composition and design. When working with hardened steel, stainless steel, or titanium, M35 and M42 cobalt bits are frequently chosen for their heat resistance and durability. Cobalt alloys maintain their edge integrity under the high friction generated during metal drilling. Conversely, step bits made from high-speed steel (HSS) offer versatility for thinner applications, allowing users to drill and deburr multiple hole sizes with a single tool. Understanding the differences between these stubby cobalt sets and multi-sized cone bits ensures you select the appropriate hardware for your specific drilling task, whether you are utilizing a standard drill or an impact driver.
For projects involving sheet metal or light-gauge materials, step bits provide an efficient solution by eliminating the need to swap bits between holes. For heavier duty applications, such as drilling cast iron or hardened stainless steel, cobalt sets are the industry standard. These sets often feature specialized shanks, such as 1/4-inch hex shanks for quick chucks or three-flat shanks to prevent rotation in the drill. By evaluating the material compatibility and shank design of each set, you can improve your workflow and achieve cleaner, more accurate results. We have analyzed several top-rated options to help you determine which bit set best aligns with your workshop requirements.
1. Crosstar 8Pc M35 Cobalt Stubby Drill Bit Set for Hard Metals, 3/32"-3/8" | Metal Drill Bits, TiAlN Coated, 1/4" Hex Shank, for Hardened Steel, Stainless Steel, Cast Iron, Titanium, Light-Gauge Metal
This 8-piece stubby set is constructed from M35 cobalt, a material specifically engineered for hard metals like hardened steel and stainless steel. The inclusion of a TiAlN coating provides additional resistance to wear and heat. Designed with a 1/4-inch hex shank, these bits are compatible with quick-change chucks, making them convenient for users working with impact drivers or standard drills. The set covers a size range of 3/32-inch to 3/8-inch, providing a versatile selection for various drilling tasks in titanium, cast iron, and light-gauge metal. Their stubby profile is intended to provide stability during operation in cramped or difficult spaces. With a 4.4-star rating, this set offers a balance of material durability and practical design for metalworking projects.
Best for: Users needing a versatile cobalt set for hard metals with quick-change compatibility.
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- M35 cobalt alloy for heat resistance
- TiAlN coating for increased durability
- 1/4-inch hex shank for quick chucks
- Stubby design for compact spaces
Keep in mind
- Limited to 8 specific sizes
- Performance may vary depending on drill speed
2. 1/8"-1/2" Quick Change M2 Step Drill Bit Unibit Hole Drilling
This M2 step drill bit is designed for users who need to drill multiple hole sizes ranging from 1/8-inch to 1/2-inch without changing tools. As a unibit design, it is well-suited for hole drilling in applications where quick adjustments are necessary. The high-speed steel (HSS) construction provides the durability required for general metal drilling tasks. Its geometry allows for both drilling and deburring in a single motion, which can streamline the process for electricians or DIY enthusiasts working with sheet metal. With a 4.6-star rating, this bit is a functional choice for those prioritizing speed and convenience in their metal drilling workflow. The design aims to simplify the transition between different hole diameters in a single pass.
Best for: Quickly creating or enlarging holes in sheet metal and thin materials.
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- 1/8-inch to 1/2-inch range
- Step design for multiple hole sizes
- High-speed steel construction
- Enables quick-change hole drilling
Keep in mind
- Limited to 1/2-inch maximum diameter
- May not be suitable for extremely thick hardened steel
3. ZELCAN 10 Sizes Titanium Step Drill Bit, 1/4 to 1-3/8 Inches High Speed Steel Drill Cone Bits for Sheet Metal Hole Drilling Cutting, HSS Multi Size Hole Stepped Up Unibit for DIY Lovers Electrician
The ZELCAN 10-size titanium step drill bit is crafted from high-speed steel (HSS) to provide a wide range of hole sizes, spanning from 1/4-inch to 1-3/8 inches. This cone-shaped bit is optimized for sheet metal hole drilling and cutting. The titanium coating is intended to reduce friction and heat during operation, which is a common requirement for metal drilling tasks. The multi-size functionality makes it a useful tool for electricians and DIY enthusiasts who frequently switch between different hole diameters. With a 4.4-star rating, this bit offers a wide capacity for enlarging holes in a single step. Its HSS construction ensures that it remains a reliable option for various sheet metal applications where precision and speed are valued in a professional or personal workshop setting.
Best for: DIYers and electricians needing a wide range of hole sizes in sheet metal.
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- 10 different hole sizes
- 1/4-inch to 1-3/8-inch capacity
- Titanium coating for reduced friction
- HSS construction for durability
Keep in mind
- Not designed for thick, hardened steel plate
- Requires careful speed control to avoid overheating
4. BOSCH CO14B 14-Piece Cobalt Drill Bit Set with Included Case - M42 Metal Drill Bits with Three-Flat Shank for Drilling Applications in Stainless Steel, Cast Iron, Titanium, and Light-Gauge Metal
The BOSCH CO14B is a 14-piece set featuring M42 cobalt drill bits, which are known for their ability to withstand the extreme heat generated while cutting through difficult materials like stainless steel and cast iron. Each bit is designed with a three-flat shank to provide a secure grip, preventing the bit from spinning in the drill chuck during high-torque applications. This set is specifically marketed for demanding metal drilling tasks, including titanium and light-gauge metal. The inclusion of a storage case helps keep the pieces organized and protected. With a 4.6-star rating, this comprehensive set is built for durability and steady performance in professional-grade metalworking environments. The M42 composition is a key feature for those who frequently work with high-friction, tough-to-drill metals.
Best for: Professional metalworkers requiring high-heat resistance and secure chuck grip.
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- M42 cobalt for high-heat applications
- Three-flat shank to prevent slippage
- 14-piece set for diverse sizing
- Includes protective storage case
Keep in mind
- Higher cost compared to basic HSS sets
- Requires consistent lubrication for optimal lifespan
5. NordWolf 5-Piece M35 Cobalt Stubby Drill Bit Set for Stainless Steel & Hard Metals, with 1/4" Hex Shank for Quick Chucks & Impact Drivers, SAE Sizes 3/32"-1/8"-3/16"-1/4"-5/16" in Storage Box
This 5-piece stubby drill bit set is manufactured from M35 cobalt, offering high performance when drilling through stainless steel and other hard metals. The bits are equipped with 1/4-inch hex shanks, making them compatible with both quick-change chucks and impact drivers. The set includes common SAE sizes from 3/32-inch to 5/16-inch, providing a focused range for smaller, precise holes. The stubby design is specifically aimed at users who need to operate in tight spaces where longer bits might be unwieldy. The included storage box ensures that the bits remain organized and protected from damage when not in use. With a 4.2-star rating, this set is a compact, durable option for metal drilling tasks that require a quick and easy tool change.
Best for: Compact drilling tasks in hard metals using impact drivers.
Check on AmazonHighlights
- M35 cobalt for hard metal applications
- 1/4-inch hex shank for quick chucks
- Stubby design for cramped workspaces
- Includes organized storage box
Keep in mind
- Limited size range of only 5 pieces
- May not be ideal for very deep hole drilling
How to choose
Material Composition
When drilling through steel, the metallurgy of the bit is the most critical factor. Cobalt steel, such as the M35 used in the Crosstar and NordWolf sets or the M42 alloy found in the Bosch CO14B set, provides superior heat resistance compared to standard high-speed steel. This prevents the bit from softening when friction builds up during high-torque applications. For stainless steel, hardened steel, or titanium, choosing M35 or M42 cobalt is essential for maintaining a sharp cutting edge. Always verify that the bit material is rated for the specific hardness of the metal you intend to penetrate to ensure the tool longevity and efficiency.
Shank Compatibility
Selecting a drill bit with the correct shank ensures a secure fit in your power tool. The Crosstar and NordWolf sets feature 1/4-inch hex shanks, which are specifically designed for quick-change chucks and impact drivers, making them highly convenient for fast bit swaps. Conversely, the Bosch CO14B set utilizes a three-flat shank design, which helps prevent the bit from spinning inside a traditional drill chuck. If you are using a standard corded or cordless drill, the three-flat shank provides a more reliable grip under heavy load, whereas the hex shank is optimized for the specific interface of impact drivers.
Geometry and Stubby Design
Stubby drill bits, like those offered by Crosstar and NordWolf, are engineered with a shorter length to increase rigidity and reduce the risk of snapping when applying pressure to hard metals. This design is particularly advantageous when working in confined spaces where a long bit might deflect or vibrate. Shorter bits offer better control, which is vital when starting a hole in tough steel materials. By minimizing the distance between the chuck and the cutting surface, these stubby bits ensure that force is transferred efficiently, reducing the likelihood of bit breakage during the initial bite into the metal surface.
Step Bit Versatility
For projects involving sheet metal or thin-gauge steel, step drill bits like the Zelcan titanium-coated HSS model or the 1/8-inch to 1/2-inch quick-change unibit offer distinct advantages. These bits allow you to drill multiple hole sizes using a single tool, eliminating the need to constantly swap bits. The stepped design automatically deburrs the hole as you drill, which is a significant time-saver for electricians and DIY enthusiasts. While they are not intended for deep holes in thick hardened steel, they are the most effective solution for creating clean, circular holes in flat metal sheets or thin conduits.
Coating and Durability
Surface coatings play a vital role in tool performance and heat dissipation. The Crosstar drill bit set features a TiAlN (Titanium Aluminum Nitride) coating, which is specifically applied to enhance durability when drilling into hardened steel and titanium. Coatings act as a thermal barrier, allowing the bit to run cooler and last longer than uncoated versions. When choosing a bit for heavy-duty metal drilling, look for these specialized coatings as they effectively reduce friction. Combined with cobalt construction, a high-quality coating ensures that the cutting edge remains sharp even when subjected to the extreme temperatures generated by drilling through dense, high-strength metals.
Frequently asked questions
Which drill bit is best for stainless steel?
For stainless steel, cobalt drill bits are the preferred choice due to their ability to withstand the high heat generated during drilling. Both the Bosch CO14B M42 cobalt set and the M35 cobalt sets from Crosstar and NordWolf are specifically engineered for this application. These materials maintain their hardness at elevated temperatures, preventing the bit from dulling quickly. Always use a low-speed setting and appropriate cutting fluid to extend the life of the bit when working with stainless steel.
Should I choose a hex shank or a three-flat shank?
The choice depends entirely on your drill. If you are using an impact driver or a drill with a quick-change chuck, the 1/4-inch hex shank bits, such as the Crosstar or NordWolf sets, are the most compatible and efficient. If you are using a standard drill, the three-flat shank found on the Bosch CO14B set is superior because it provides a secure, non-slip grip in the chuck, preventing the bit from spinning when you encounter resistance in tough steel.
Can I use a step drill bit to drill through thick steel?
Step drill bits like the Zelcan titanium HSS model or the 1/8-inch to 1/2-inch unibit are primarily designed for thin-gauge metal and sheet steel. They are highly efficient for creating holes of varying diameters in thin material, but they are not the ideal tool for drilling through thick, hardened steel. For thicker materials, use a standard cobalt twist bit, such as those found in the Bosch, Crosstar, or NordWolf sets, which are designed for deeper, more demanding penetration.
What is the benefit of a stubby drill bit?
Stubby drill bits, such as the Crosstar and NordWolf options, are shorter than standard-length bits. This shorter profile makes them significantly more rigid, which reduces the chance of the bit bending or snapping under the high pressure required to drill through hard steel. Additionally, their compact size allows for better maneuverability in tight work areas. By minimizing vibration and deflection, stubby bits provide a higher level of precision and durability when initiating a cut into dense or hardened metal surfaces.
Do I need a special bit for titanium?
Yes, drilling through titanium requires bits made from high-performance materials like M35 or M42 cobalt, such as those in the Bosch, Crosstar, and NordWolf sets. These bits are specifically rated for titanium and other hard metals because they can withstand the intense friction and heat generated during the process. Using a standard high-speed steel bit on titanium will likely result in the bit dulling instantly. Always prioritize bits explicitly labeled for use with hardened steel and titanium for successful results.
Bottom line
For the most demanding steel-drilling tasks, the Bosch CO14B 14-Piece Cobalt Drill Bit Set stands out as the most robust option. Its utilization of M42 cobalt, combined with a three-flat shank, provides the necessary structural integrity and grip required for high-torque applications in stainless steel, cast iron, and titanium. For users operating impact drivers, the Crosstar 8Pc M35 Cobalt Stubby Drill Bit Set offers the best balance of heat resistance and convenience; its TiAlN coating and 1/4-inch hex shank make it an excellent choice for hardened steel. Both sets offer superior longevity compared to standard HSS bits, ensuring that the cutting edges remain effective even under the extreme stress of drilling through dense metal alloys.
Deciding between these options depends on your specific tool and the thickness of the metal. If you are drilling through thin sheet metal or need multiple hole diameters, the Zelcan Titanium Step Drill Bit is the most efficient choice for clean, burr-free results. If your project requires drilling deep holes into thick, hardened steel, opt for the Bosch CO14B for its superior shank stability or the Crosstar stubby set for its unmatched rigidity. Always match the shank type to your drill—hex for impact drivers and three-flat for standard chucks—to ensure safety and performance. By selecting the correct bit metallurgy and geometry, you can reliably penetrate the toughest steel surfaces.
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