How and at what angle should you sharpen drill bits?

From this article you will learn:

• Why and how to sharpen drill bits.
• How to follow safety rules when sharpening drill bits.

Why is it worth sharpening drill bits?

Sharpening drill bits is a key part of maintenance that affects work quality and efficiency. A dull drill bit requires more pressure, which results in slower drilling, higher energy consumption, and the risk of overheating both the tool and the workpiece. This can lead to uneven hole edges and, in extreme cases, damage to the drill bit or breaking its tip.

Regular sharpening contributes to more precise drilling, which is especially important in metalworking, where hole accuracy matters. A properly sharpened drill bit removes chips more effectively, which reduces the risk of the tool jamming and improves work safety. Proper sharpness of the cutting edges also reduces the load on the machine tool, which can translate into a longer service life of the machines.

At what angle should drill bits be sharpened?

The drill point angle is crucial for effectiveness and for matching the drill bit to the material being machined. At what angle should drill bits be sharpened? The drill bit sharpening angle depends on the material you will be drilling:

• Drill bits for metal: The standard point angle is 118 degrees. This is a universal value suitable for most metals. For harder materials, such as stainless steel, increasing the angle to 135 degrees is recommended, which reduces cutting forces and extends drill bit life.

• Drill bits for wood: They usually have a sharpening angle of about 90 degrees. This allows the drill bit to penetrate soft wood fibers effectively, minimizing the risk of cracking and splitting.

• Drill bits for concrete: They require a larger angle, often 135 degrees, to cope effectively with hard and brittle materials.

How to sharpen metal drill bits?

Sharpening metal drill bits is a process that requires precision and can be done manually on a bench grinder or using specialist sharpeners. How to sharpen metal drill bits? Sharpening metal drill bits can be carried out in several ways:

1. Manual sharpening using a bench grinder: Make sure the grinder is equipped with the appropriate grinding wheel. For metal drill bits, a medium-grit aluminum oxide wheel is recommended. Hold the drill bit at a 118-degree angle to the wheel. You can use a protractor or a special attachment to set the correct angle. Gently press the drill bit against the wheel, rotating it around its axis to maintain symmetry of the cutting edge. Avoid overheating the drill bit by taking breaks during sharpening and cooling the tool in water.
2. Using a drill bit sharpener: These devices enable precise sharpening of drill bits at the correct angle. Simply place the drill bit in the appropriate holder, set the desired angle, and start the machine. Sharpeners provide greater precision and repeatability compared to manual sharpening. They are especially recommended for professionals and workshops with high work intensity.

Industrial machinery manufacturer Cormak offers a wide range of drill bit sharpeners and tool grinders that facilitate the drill bit sharpening process.

Which grinding wheel for sharpening drill bits?

Choosing the right wheel for sharpening drill bits is crucial to ensure effective sharpening and to extend tool life. Which wheel will be best depends on the drill bit material and the type of grinder used for sharpening.

• Aluminum oxide wheels – Most commonly used for sharpening high-speed steel (HSS) drill bits. They have high wear resistance and allow precise sharpening of cutting edges. They are available in different grits – for drill bit sharpening, a medium grit is recommended, providing an optimal balance between grinding speed and machining precision.
• Diamond wheels – Essential for sharpening carbide drill bits used for drilling in concrete and hard metal alloys. Diamond wheels provide exceptional precision and long service life, but their price is higher than aluminum oxide counterparts.
• CBN wheels (cubic boron nitride) – Recommended for sharpening drill bits made of very hard alloys, such as cobalt (HSS-Co) or tools with titanium coatings. They are highly resistant to high temperatures and do not overheat the machined surface.

It is important that the wheel is properly matched to the drill bit material and has the correct grit size, which ensures effective and precise sharpening.

Safety when sharpening drill bits

Sharpening drill bits requires appropriate precautions, because improper technique or lack of protection can lead to injuries and tool damage. Whether sharpening is done manually on a bench grinder or using an automatic sharpener, a few basic rules must be followed.

First of all, eye protection is extremely important – sparks and metal particles may be produced during grinding, which can be hazardous. It is mandatory to use safety glasses, and for intensive work it is worth considering a full face shield.

You should also pay attention to hand protection, although using protective gloves requires caution. When working on a bench grinder, loose or thick gloves can reduce precision and increase the risk of the material being pulled in by the rotating wheel. Instead, ensure a secure grip on the drill bit and stable hand positioning.

Another important aspect is proper cooling of the drill bit. Excessive heating of the tip during sharpening can lead to the loss of hardened cutting edge properties. To prevent this, regularly immerse the drill bit in water or a special cooling oil, which helps maintain its durability and cutting properties.

Summary

Regular drill bit sharpening is a key part of maintenance that affects drilling quality and precision. It is worth knowing how metal drill bits are sharpened and how to sharpen a drill bit properly. A properly sharpened tool not only speeds up work, but also reduces energy consumption and machine load. Choosing the right sharpening angle and the right wheel allows you to effectively restore the original properties of drill bits, whether they are intended for metal, wood, or concrete.

To make the sharpening process easier and more efficient, it is worth using professional bench grinders and tool grinders, which provide precise grinding of cutting edges. It is also worth remembering that a well-sharpened drill bit is only one element of effective machining – in the workshop, metal lathes and metal milling machines will also be useful for further cutting processes.

If you are looking for comprehensive solutions, check the offer of metalworking machines in the Cormak store and choose equipment tailored to your needs.