Most woodworkers have faced the problem of dull chisels. New woodworkers, or those new to working with chisels, face the challenge of sharpening their chisels. Some opt to take their chisels to a professional sharpener or have a whetstone just for this purpose. Others look around their shop and ask the question, “Can I sharpen my chisels on a bench grinder?”
You can sharpen your chisels on a bench grinder. Your bench grinder must have enough power and the correct type of stone. More importantly, you must use techniques that maintain the correct bevel and avoid overheating the steel in your tool, which can soften the cutting edge.
Many woodworkers use a bench grinder to sharpen their chisels. Before you attempt to use your bench grinder to put the edge back on your tools, you should understand the sharpening process and how it can affect your tools’ steel. We’ll explain how to use your bench grinder properly so that you won’t damage your chisels beyond repair.
Get the Right Equipment for the Job
You can remove metal from a tool with almost any bench grinder. Removing metal, the right way to leave a clean, sharp edge, is the challenge. Getting the clean, sharp edge with softening the steel of your tool the goal. Attaining this goal requires the right tools and the right technique.
There are certain things you need in a bench grinder used for sharpening chisels.
Size and Power
Your bench grinder must be large enough and powerful enough to maintain the grinding wheel’s speed even when applying pressure to the wheel. A bench grinder with at least an eight-inch wheel is the smallest you should use in most cases.
Get the Right Grinding Wheel
There are two components to finding the right grinding wheel for sharpening your chisel. The grade of the wheel tells you the hardness of the material in the wheel. The grit size refers to the size of the grains of the material in the grinding wheel. For sharpening fine-edged tools such as chisels, a grinding wheel with medium hardness and grit size of 60 is preferable.
Well Mounted and Properly Positioned
Your bench grinder should be securely mounted to a sturdy workbench or stand that won’t wobble, tilt, or move when you are working. Mounting your bench grinder about waist height allows you to work standing straight to prevent fatigue.
A Grinding Jig
While not necessary, a grinding jig keeps your chisels at the perfect angle. With experience, you can learn to do this without a jig. Jigs can be home-built or purchased as aftermarket kits. Professional sharpeners depend on jigs to produce perfect grinds and razor-sharp tools.
Your Safety Equipment
Grinding metal tends to produce a lot of flying objects. Small particles of extremely hot metal are the by-product of sharpening on a bench grinder. You need to protect yourself with the proper equipment. Eye protection is a must, and you should wear gloves. A leather work apron will protect your clothing and keep the hot metal from getting to your skin.
Understanding the Metal in your Chisels
The metal on the cutting end of your chisels is not just any steel. On good chisels, the sharp edge of the chisels is special alloys designed especially for cutting edges. The steel alloy gives hardness that holds an edge yet is soft enough to sharpen when needed. If you are shopping for a good set of chisels, look for tools made with steels such as:
- Chromium Vanadium (CV)
- Chromium Manganese (CM)
- O1 and A2
Alloys such as A2 and PM-V11 are harder and will hold an edge longer. Chisels made with these steels are harder to sharpen and may require special techniques. O1, CV, and CM are slightly softer and, therefore, easier to sharpen. You give up a bit of edge retention with this softer steel.
Sharpening on a Bench Grinder – Do’s and Don’ts
You should do some things and some things you should avoid sharpening your chisels on a bench grinder successfully. As with any task, doing things the proper way is the first step to success. Remember, the goal is to give your chisels a clean, sharp, and long-lasting cutting edge.
Sharpen your Chisels to the Proper Bevel Angle
The primary bevel on most bench chisels should be ground or honed to 25 degrees. This angle gives the best result overall. Some fine woodworkers add a second micro-bevel to the very cutting edge of their chisels. A micro-bevel is particularly effective on steels such as O1, which should get a secondary bevel of 30 degrees, and A2 steel on which a 35-degree micro bevel is best.
Use a Jig for Best Results
Bevel angle on the cutting edge of your chisels is essential for long edge life and clean cutting. Only the most experienced sharpeners can judge the bevel angle by eye during freehand sharpening. Even most professional sharpeners depend on jigs to hold the chisels at the proper angle during sharpening.
You can buy excellent sharpening systems that include:
- Grinding wheels,
- Grinding machines
These systems tend to be pricey and maybe beyond the reach of many hobby woodworkers. However, the internet is a great source of plans for easy-to-build sharpening jigs that are adaptable to almost any bench grinder.
Buy Good Chisels Made from High-Quality Steel
Starting with a chisel made with high-quality tool steel will save you hours of frustration down the line. You can sharpen almost any steel to a fine edge that will cut well. The problem is that mild steel will not hold that edge and will require constant attention. Steels that are too hard or brittle will chip and are next to impossible to sharpen.
Buy the best chisels you can afford from reputable companies. Off-brand and inexpensive chisels come from overseas, and the quality of the steel is always a mystery. Save yourself time and frustration by selecting quality tools from known vendors that will last you a lifetime.
I recommend, for a starter chisel set, this 4 pack of Dewalt chisels.(Check out the price on Amazon Here)
The Last Tip – Learn to Hone your Chisels
Honing is a process of flattening the back of a cutting tool such as a chisel or a plane iron. This flattening is the key to the finest cutting edge possible. Many woodworkers use a piece of granite or tempered glass and 800 to 3000 grit sandpaper to hone the backs of their chisels.
The honing process should be done slowly and carefully to avoid removing too much metal. The goal is a perfectly flat and polished surface on the back of your chisel. This polished surface allows your chisel to slide effortlessly on its back, keeping the edge perfectly parallel to the surface. This polish allows your chisel to work as a plane to remove small bumps and irregularities.
The Key to Sharpness – The Hardening and Tempering the Steel
During the manufacture of tools with cutting edges, particularly chisels, the steel is hardened and tempered. Steel is hardened by heating the metal to a specified temperature and quenching the steel in a cooling liquid. This hardening process changes the internal structure of the steel, making it much harder and more durable.
Tempering restores a bit of the softness to the steel making it less brittle. Tempered steel is usually hard enough to take and hold a fine cutting edge yet soft enough not to break or shatter if dropped.
Be Sharp in Your Shop – Keep the Cutting Edge
Sharp tools are a joy. They make your work easier overall. Sharpening your chisels can be done on a bench grinder with a little preparation and understanding. Working with good tools will make life easier and give you years of pleasure in the process.