Drill Grinding Attachment – Save Your Bits And Sharpen Like A Pro

ByJim Boslice Metalworking & Fabrication

A drill grinding attachment allows you to restore the cutting edge of dull high-speed steel (HSS) twist bits using your existing power drill or bench grinder.

By precisely maintaining the correct relief angle and point geometry, you can extend the life of your drill bit collection and ensure cleaner, faster holes in metal and wood.

We have all been there. You are halfway through a critical project, you reach for your favorite 1/4-inch bit, and it just skates across the surface of the metal like a dull butter knife. It is frustrating, it slows down your momentum, and it often leads to ruined workpieces.

The good news is that you do not need to toss those dull bits into the scrap bin. With a quality drill grinding attachment, you can bring them back to life in just a few minutes. It is a fundamental skill that every garage tinkerer and woodworker should master to save money and stay productive.

In this guide, I will walk you through how these tools function, how to set them up for consistent results, and the safety measures you need to keep in mind. Let’s get your workshop running at full efficiency again.

Understanding the Drill Grinding Attachment Mechanism

At its core, a drill grinding attachment is a jig designed to hold a twist drill bit at the exact angle required to restore its cutting geometry. Most twist bits are ground to a 118-degree point angle, which is the standard for general-purpose drilling.

These attachments typically feature a V-shaped groove or a cradle that keeps the bit centered as you move it against a grinding wheel. By locking the bit in place and rotating it against the abrasive surface, you recreate the original factory bevels.

Without this mechanical aid, sharpening a bit by hand on a bench grinder is a high-stakes game of guesswork. It is incredibly difficult to maintain the necessary relief angle—the slope behind the cutting edge—without a jig to guide your movements.

Why Precision Geometry Matters for Your Bits

When a bit is dull, the metal doesn’t cut; it gets pushed aside by friction. This generates immense heat, which softens the steel of the bit, causing it to dull even faster and potentially work-harden the material you are trying to drill.

A sharp bit acts like a chisel. It slices through the material, creates clean chips, and draws the heat away from the workpiece. Using a grinding jig ensures that both cutting lips of the bit are identical in length and angle.

If one side is longer than the other, the drill bit will wobble. This results in an oversized, oblong hole that is rarely accurate. A consistent attachment ensures that your bits are balanced and ready for precision work.

Step-by-Step: How to Use Your Drill Grinding Attachment

Before you start, make sure your bench grinder is securely mounted to your workbench. Vibration is the enemy of precision. Always wear safety glasses and hearing protection, as metal filings will be flying during the process.

  1. Inspect the bit: Check for major chips or blue discoloration, which indicates the steel has already been overheated and softened.
  2. Set the jig: Adjust the stop on your drill grinding attachment to match the diameter of the bit you are sharpening.
  3. Position the bit: Place the bit into the jig so the cutting lip is flush against the guide surface.
  4. The Grind: Gently advance the jig toward the wheel. Use light pressure and frequent quenching in a jar of water to prevent overheating.
  5. The Flip: Rotate the bit 180 degrees and repeat the process on the other side. Take your time to ensure the two sides match perfectly.

Common Pitfalls and How to Avoid Them

The most common mistake beginners make is applying too much pressure. When you press too hard, you generate excessive heat, which ruins the temper of the steel. You want to hear a light “hiss” or “sizzle,” not a roar.

Another issue is failing to maintain the relief angle. If you grind the back of the cutting edge too flat, the bit will rub against the material rather than biting into it. If you grind it too steeply, the edge becomes thin and brittle, leading to immediate chipping.

If you are struggling to get a clean edge, check your grinding wheel. A glazed wheel—one filled with metal particles—will burn the steel instead of cutting it. Use a dressing tool to clean the wheel surface regularly.

Material Selection and Safety Considerations

While most attachments work well on standard high-speed steel (HSS) bits, be careful with cobalt or carbide bits. Cobalt bits are tougher and require specific abrasive wheels to sharpen effectively.

If you are working with masonry bits, note that they often have carbide tips that require diamond-grit wheels. Never try to sharpen a masonry bit on a standard aluminum oxide wheel; you will only wear down the wheel without touching the carbide.

Always keep your workspace clean. Metal dust and sparks are a fire hazard, especially in a woodworking shop. Keep a fire extinguisher nearby and ensure your clothing is free of loose threads or flammable materials.

Frequently Asked Questions About Drill Grinding Attachment Use

Can I sharpen any size drill bit with a standard attachment?

Most consumer-grade jigs are limited to bits between 1/8 inch and 1/2 inch. For extremely small bits, the setup becomes fiddly, and for very large bits, the jig may not provide enough stability.

How do I know if my drill bit is sharp enough?

A sharp bit will produce long, spiraling metal shavings when drilling into mild steel. If you only see fine dust or short, broken chips, your bit is likely dull or the geometry is incorrect.

Do I need to sharpen the center point of the bit?

The “web” or center point of the bit can become thick after multiple sharpenings. If you find the bit requires a lot of downward pressure to start drilling, you may need to “thin the web” using the edge of your grinding wheel.

How long does a bit stay sharp after using a grinder?

It depends on the material you are drilling. In soft wood, a bit can last for hundreds of holes. In stainless steel or hard-cast iron, you may need to touch up the edge after just a few holes to maintain peak performance.

Master Your Workshop Maintenance

Investing time in learning how to use a drill grinding attachment pays off in the long run. Not only do you save money by not constantly replacing your bit sets, but you also gain the confidence that comes with knowing your tools are performing at their best.

Start by practicing on some of your older, “junk” bits that you don’t mind ruining. Once you get the feel for the pressure and the sound of a proper grind, you will find it becomes second nature.

Keep your workshop organized, prioritize your safety, and keep those edges keen. Happy building, and remember—a sharp tool is a safe and effective tool.

Jim Boslice
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