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How To Drill Hardened Steel

Drilling through hardened steel can be a daunting task, even for experienced DIY enthusiasts. The rigid, durable material can quickly dull or break drill bits, making it frustrating and time-consuming.

However, with the proper techniques and tools, drilling through hardened steel can be a breeze.

To drill through hardened steel:

  1. Mark the location of the hole with a center punch.
  2. Use a carbide drill bit that is slightly smaller than the desired hole size.
  3. Apply a lubricant to the drill bit and the workpiece. This will help to reduce friction and heat buildup.
  4. Drill slowly and carefully, applying light pressure.
  5. Clear the chips out of the hole frequently to prevent clogging.
  6. Once the hole is drilled to the desired depth, remove the drill bit and clean the hole with a wire brush.

In this article, we will discuss essential tips and techniques for mastering the art of drilling hardened steel.

Choose the Right Drill Bit

The first and most crucial step in drilling through hardened steel is choosing the right drill bit. Regular drill bits are not strong enough to penetrate hardened steel, so you must invest in a set of high-speed steel (HSS) or cobalt drill bits.

These types of drill bits are specifically designed to withstand the high heat and pressure of drilling through hardened steel.

Additionally, make sure to use a drill bit slightly smaller than the desired hole size, as this will reduce the risk of the bit breaking.

Use Lubrication

Use Lubrication
Source: WD-40

Hardened steel generates a lot of heat when drilled, which can quickly dull or damage the drill bit. It is essential to use lubrication while drilling.

You can use a commercial cutting fluid or a simple household oil like vegetable or motor oil. Apply the lubricant to the drill bit and the steel surface before drilling.

This will help reduce friction and heat, making the drilling process smoother and more efficient.

Start Slow and Steady

When drilling through hardened steel, it is crucial to start slow and steady. High-speed drilling can generate heat, damaging the drill bit and the steel.

Begin by setting your drill to a low speed and gradually increase it as needed. This will also give you more control over the drilling process, allowing you to make precise and accurate holes.

Use a Center Punch

It is essential to use a center punch. This tool creates a slight indentation in the steel, providing a starting point for the drill bit.

This will help keep the drill bit in place and prevent it from wandering or slipping, which can cause damage to the bit and the steel.

Cool Down Periods

Cool Down Periods
Source: WireCutter

As mentioned earlier, drilling through hardened steel generates a lot of heat, which can damage the drill bit. It is essential to take cool-down periods while drilling.

After every few seconds of drilling, stop and remove the bit from the steel. This will allow the bit to cool down and prevent it from overheating and breaking.

Seek Professional Help

If you need more confidence in your ability to drill through hardened steel, it is always best to seek professional help.

A professional metalworker or a hardware store employee can provide expert advice and even drill the holes for you. This will save you time, effort and the risk of damaging your tools or the steel.

By following these essential tips and techniques, you can master the art of drilling through hardened steel.

Remember to choose the right drill bit, use lubrication, start slow and steady, use a center punch, take cool-down periods, and seek professional help. With practice and patience, you can drill through hardened steel like a pro.

Tips and Techniques To Drill Through Hardened Steel

  • Peck Drilling Technique: When drilling through hardened steel, practice peck drilling—drill a bit, retract to clear the chips, then drill again. This method prevents overheating and prolongs the life of the drill bit.
  • Maintain Sharp Bits: Keep your drill bits sharp. Dull bits will not only make the process slower but also generate more heat, reducing their efficiency. Regularly sharpen or replace your drill bits as needed.
  • Secure the Steel: Ensure the steel you’re drilling is clamped down or secured firmly. This prevents any movement that could cause the drill to slip or break.
  • Consider Carbide Bits for Very Hard Steel: In cases where the steel is extremely hardened, consider using carbide drill bits. They are incredibly hard and can drill through the toughest of steel, though they might be more brittle.
  • Use a Center Punch: Before drilling, make a small indentation on the steel’s surface using a center punch. This provides a starting point for your drill bit and helps maintain precision.

Remember, safety is key. Always wear appropriate protective gear such as safety glasses and gloves when working with power tools.

Take your time, follow these tips, and with patience and the right tools, you can successfully drill through hardened steel.


In conclusion, drilling through hardened steel requires patience, the right tools, and the correct techniques.

Utilizing cobalt or carbide drill bits, a slow drilling speed, and lubrication can make the process more manageable.

Remember, it’s crucial to maintain a steady hand, applying firm but not excessive pressure. Cooling the steel intermittently prevents overheating and preserves the drill bit.

Always wear protective gear and work in a well-ventilated area for safety. While challenging, with the proper approach, drilling through hardened steel can be accomplished effectively. Practice and persistence will enhance your skill in handling this tough material.


What type of drill bit should I use to drill through hardened steel?

For drilling through hardened steel, cobalt or carbide drill bits are recommended due to their hardness and heat resistance.

How do I maintain a steady drilling speed when working on hardened steel?

To maintain a steady drilling speed, use a variable speed drill and begin at a slow speed. Gradually increase speed while applying consistent pressure to avoid overheating the bit.

Can I use a regular drill to penetrate hardened steel?

Using a regular drill might not be effective. It’s recommended to use a high-quality, powerful drill with the appropriate bits designed for hardened steel.

How can I lubricate the drill bit when drilling through hardened steel?

Apply a suitable lubricant, such as cutting oil or a coolant, to the area being drilled. This reduces friction and helps dissipate heat, prolonging the life of the drill bit.

What safety precautions should I take when drilling through hardened steel?

Ensure you wear safety goggles and gloves. Secure the steel piece properly and take breaks to prevent overheating. Use proper lubrication and be cautious to avoid injury while working with the drill.

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