How To Sharpen Drill Bits With Grinder: Tips & Safety Measures

Can you sharpen drill bits with a grinder? Yes, you can! Using a drill bit sharpening grinder is a common and effective way to keep your drill bits in optimal condition. This comprehensive guide covers everything you need to know about sharpening drill bits, including drill bit sharpening techniques, understanding the drill bit sharpening angle, how to use a bench grinder drill bit sharpener, and essential safety measures. This article will teach you how to avoid sharpening dull drill bits improperly and ensure efficient drilling.

Why Sharpen Your Drill Bits?

Why is sharpening drill bits so important? Dull drill bits are inefficient and can cause several problems:

• Increased Effort: You have to apply more pressure to get the bit to cut.
• Overheating: Friction from a dull bit generates excessive heat, potentially damaging the bit and the material you’re drilling.
• Inaccurate Holes: Dull bits can wander, resulting in holes that are not precisely where you need them.
• Bit Breakage: Applying excessive force can lead to the bit snapping, especially with smaller sizes.
• Damage to Material: A dull bit can tear or splinter the material, especially when working with wood or plastic.

Tools and Equipment Needed

Before you begin grinding drill bits, gather the necessary tools and equipment:

• Bench Grinder: A bench grinder with a medium-grit grinding wheel is essential.
• Safety Glasses: Always protect your eyes from flying sparks and debris.
• Work Gloves: Provide a better grip and some protection against heat.
• Water Container: For cooling the drill bit during grinding.
• Drill Bit Gauge (Optional): Helps to check and maintain the correct drill bit sharpening angle.
• Dust Mask (Optional): Protects against inhaling grinding dust.
• Lighting: Ensure adequate lighting for clear visibility.

Safety First: Essential Precautions

Sharpening drill bits on bench grinder can be dangerous if safety precautions are not followed.

• Eye Protection: Always wear safety glasses or a face shield.
• Hand Protection: Use work gloves to protect your hands from heat and sharp edges.
• Proper Ventilation: Work in a well-ventilated area to avoid inhaling grinding dust.
• Secure the Grinder: Ensure the bench grinder is securely mounted to prevent it from moving during operation.
• Inspect the Wheel: Check the grinding wheel for cracks or damage before each use.
• Cool the Bit: Dip the drill bit frequently in water to prevent overheating and loss of temper.
• Keep Fingers Clear: Maintain a safe distance between your fingers and the grinding wheel.
• Stay Focused: Avoid distractions and concentrate on the sharpening process.

Getting Ready to Sharpen

Before you start how to sharpen drill bits, take the time to prepare your workspace and the drill bits.

Inspecting the Drill Bit

Carefully examine the drill bit to identify the areas that need sharpening. Look for:

• Rounded cutting edges
• Chips or damage on the cutting lips
• A dull or worn appearance

Cleaning the Drill Bit

Use a wire brush to remove any dirt, rust, or debris from the drill bit. This will allow you to see the cutting edges more clearly and ensure a cleaner grinding process.

Setting Up the Bench Grinder

• Adjust the Tool Rest: Position the tool rest close to the grinding wheel, leaving a small gap (about 1/8 inch).
• Ensure Proper Lighting: Make sure you have adequate lighting to see the cutting edges clearly.
• Prepare Water Container: Place a container of water near the grinder for cooling the drill bit.

The Step-by-Step Guide to Sharpening Drill Bits

This section explains the key drill bit sharpening techniques.

Step 1: Grinding the Cutting Lips

The primary goal is to restore the original drill bit sharpening angle on the cutting lips.

1. Positioning: Hold the drill bit at the correct angle against the grinding wheel. This angle is typically around 59 degrees, but it can vary depending on the type of drill bit.
2. Gentle Pressure: Apply gentle, consistent pressure to the cutting lip against the wheel.
3. Rocking Motion: Use a slight rocking motion to evenly grind the cutting lip.
4. Cooling: Dip the drill bit in water frequently to prevent overheating.
5. Repeat: Repeat the process on the other cutting lip, ensuring both lips are ground equally.

Step 2: Grinding the Clearance Angle

The clearance angle is the angle behind the cutting lip that allows the bit to cut efficiently.

1. Positioning: After grinding the cutting lips, adjust the angle slightly to grind the clearance behind the cutting edge.
2. Light Pressure: Use light pressure and a gentle rocking motion.
3. Cooling: Cool the bit frequently.
4. Visual Check: Visually inspect the clearance angle to ensure it is consistent on both sides.

Step 3: Honing the Cutting Edges

Honing removes any burrs or sharp edges left by the grinding process.

1. Fine Grit Stone: Use a fine-grit honing stone or a ceramic rod.
2. Gentle Strokes: Gently stroke the cutting edges with the honing stone.
3. Check for Sharpness: Check the cutting edges to ensure they are sharp and free of burrs.

Checking for Centered Point

A centered point is critical for accurate drilling.

1. Visual Inspection: Visually inspect the point of the drill bit to ensure it is centered and symmetrical.
2. Corrective Grinding: If the point is off-center, carefully grind one cutting lip more than the other to correct it.
3. Re-check: Re-check the point after each adjustment until it is properly centered.

Mastering the Drill Bit Sharpening Angle

The drill bit sharpening angle is crucial for efficient drilling. The standard angle for general-purpose drill bits is 118 degrees (59 degrees per side). However, different materials and applications may require different angles.

Drill Bit Type	Point Angle	Application
General Purpose	118 degrees	Wood, metal, plastic
Soft Materials	90 degrees	Aluminum, copper
Hard Materials	135 degrees	Stainless steel, hardened steel
Masonry	60 degrees	Brick, concrete, stone
Brad Point (Wood)	90 degrees	Wood, creating clean and precise holes

Using a drill bit sharpening jig can help you maintain the correct angle consistently.

Using a Drill Bit Sharpening Jig

A drill bit sharpening jig is a tool that helps you hold the drill bit at the correct angle while grinding. This can make the sharpening process easier and more accurate, especially for beginners.

Types of Drill Bit Sharpening Jigs

• Simple Angle Guides: These jigs provide a reference angle to help you position the drill bit.
• Adjustable Jigs: These jigs allow you to adjust the angle to suit different drill bit types and materials.
• Powered Sharpeners: These are specialized machines that automatically sharpen drill bits.

How to Use a Drill Bit Sharpening Jig

1. Mount the Jig: Secure the jig to your workbench or grinder.
2. Insert the Drill Bit: Place the drill bit into the jig, aligning it with the correct angle.
3. Grind the Cutting Lips: Follow the jig’s instructions to grind the cutting lips evenly.
4. Cool the Bit: Cool the drill bit frequently to prevent overheating.
5. Check the Sharpness: Check the sharpness and angle of the drill bit after grinding.

Tips for Sharpening Different Types of Drill Bits

Different types of drill bits may require slightly different drill bit sharpening techniques.

High-Speed Steel (HSS) Drill Bits

HSS drill bits are the most common type and can be sharpened using the standard method described above.

Cobalt Drill Bits

Cobalt drill bits are designed for drilling hard materials like stainless steel. They require a slightly more obtuse angle (around 135 degrees).

Titanium-Coated Drill Bits

Titanium coatings can wear off during grinding, so avoid excessive grinding and focus on sharpening only the cutting edges.

Masonry Drill Bits

Masonry drill bits have a carbide tip that requires a specialized grinding wheel. Use a silicon carbide grinding wheel and light pressure to avoid damaging the tip.

Step Drill Bits

Step drill bits are difficult to sharpen and often require specialized equipment or professional sharpening services.

Common Mistakes to Avoid

• Overheating the Drill Bit: Excessive heat can cause the bit to lose its temper and become brittle.
• Grinding at the Wrong Angle: Incorrect angles can result in inefficient cutting or bit breakage.
• Uneven Grinding: Grinding one cutting lip more than the other can cause the bit to drill off-center.
• Using the Wrong Grinding Wheel: Using a wheel that is too coarse or too fine can damage the drill bit.
• Neglecting Safety Precautions: Failing to wear safety glasses or use proper ventilation can lead to serious injuries.

Maintaining Your Sharpened Drill Bits

• Store Properly: Store drill bits in a drill bit index or case to protect them from damage.
• Clean Regularly: Clean drill bits after each use to remove debris and prevent rust.
• Sharpen as Needed: Sharpen drill bits whenever they become dull to maintain optimal performance.
• Lubricate: Apply cutting fluid or lubricant when drilling hard materials to reduce friction and heat.

Bench Grinder Drill Bit Sharpener Options

While you can sharpen freehand, several bench grinder drill bit sharpener attachments exist to make the process easier and more accurate.

Popular Bench Grinder Drill Bit Sharpeners:

• Wolverine Grinding Jig: A versatile jig for various sharpening tasks, including drill bits.
• Drill Doctor: A specialized drill bit sharpener that automates the sharpening process.
• General Tools Drill Sharpening Attachment: A simple and affordable attachment for basic drill bit sharpening.

These attachments often include guides and angle adjustments to help you achieve a consistent and accurate grind.

Fathoming Grinding Wheels

The type of grinding wheel you use is crucial for effective drill bit sharpening.

• Aluminum Oxide Wheels: These are general-purpose wheels suitable for sharpening HSS drill bits.
• Silicon Carbide Wheels: These wheels are used for sharpening carbide-tipped drill bits and other hard materials.
• CBN (Cubic Boron Nitride) Wheels: These are premium wheels that offer excellent performance and long life for sharpening high-speed steel and cobalt drill bits.

Choose a wheel with the appropriate grit for sharpening drill bits. A medium grit (around 60-80) is generally suitable for initial sharpening, while a fine grit (100 or higher) is ideal for honing.

When to Replace a Drill Bit

Even with careful sharpening drill bits, there comes a time when a drill bit is beyond repair and needs to be replaced.

• Severely Damaged: If the drill bit is broken, bent, or has large chips, it should be replaced.
• Excessively Worn: If the drill bit has been sharpened many times and is significantly shorter than its original length, it should be replaced.
• Loss of Temper: If the drill bit has been overheated and has lost its temper, it will become brittle and prone to breakage.

Frequently Asked Questions (FAQ)

• How often should I sharpen my drill bits?
  • Sharpen your drill bits whenever they become dull or show signs of wear. This could be after each use for heavy-duty applications or less frequently for occasional use.
• Can I sharpen drill bits with a Dremel?
  • Yes, you can, but it requires a steady hand and the right attachment. Dremel offers grinding stones specifically for sharpening small drill bits.
• What is the best angle for sharpening drill bits?
  • The best angle for general-purpose drill bits is 118 degrees (59 degrees per side).
• How do I prevent overheating the drill bit while sharpening?
  • Dip the drill bit in water frequently to keep it cool and prevent loss of temper.
• Is it worth buying a drill bit sharpener?
  • If you frequently use drill bits, a drill bit sharpener can save you money and time by extending the life of your bits.
• Can I sharpen left-handed drill bits?
  • Yes, but you need to grind the opposite cutting lip compared to right-handed bits. The process is essentially mirrored.
• How do I sharpen very small drill bits?
  • Sharpening very small drill bits requires extra care and precision. Using a magnifying glass or a specialized small drill bit sharpener can be helpful.
• What type of grinding wheel is best for sharpening carbide drill bits?
  • A silicon carbide grinding wheel is best for sharpening carbide-tipped drill bits.
• What are signs that my drill bit is too dull to sharpen?
  • Signs include excessive vibration during drilling, difficulty starting a hole, burning or smoking, and requiring excessive pressure to drill.

By following these tips and safety measures, you can effectively sharpen drill bits with a grinder, saving money and improving the efficiency of your drilling projects. Mastering drill bit sharpening techniques is a valuable skill for any DIY enthusiast or professional.