How do you sharpen chisels with a grinder?

Sharpening chisels is an essential skill for any woodworker. Using a grinder to sharpen chisels is a quick and effective method that can restore a razor sharp edge. This article will provide step-by-step instructions on how to properly sharpen chisels on a grinder.

What You’ll Need

Before getting started, you’ll need to gather the following supplies:

• Bench grinder
• Grinding wheel suitable for metal (80-120 grit)
• Water dish
• Chisel honing guide
• Safety glasses
• Leather stropping wheel
• Honings compound

A basic bench grinder with an 80-120 grit wheel is ideal for grinding chisel bevels. The coarse grit will allow you to shape and sharpen the edges quickly. Make sure the wheels have been dressed to ensure they are perfectly round.

You’ll need a water dish filled with water to dip your chisels in intermittently as you grind them. This is important to keep the metal cool and prevent overheating.

A honing guide is highly recommended for holding your chisels at the perfect angle for sharpening. Otherwise, it can be extremely difficult to manually hold them at a consistent angle.

Safety glasses should always be worn when using grinding wheels. Make sure they wrap around and adequately shield your eyes from flying sparks.

Finally, a leather stropping wheel charged with honing compound can refine your edges to hair-popping sharpness once grinding is complete.

How to Sharpen Chisels on a Grinder

Follow these steps to properly sharpen your chisels on a grinder:

1. Secure the honing guide to your workbench, and clamp the chisel firmly in place at the desired bevel angle. 25-30° is typical.
2. Turn on the grinder and apply the chisel to the grinding wheel using light pressure. Grind from side to side.
3. Dip the chisel in water frequently, at least every 5-10 seconds. This prevents overheating.
4. Maintain a consistent angle as you grind. Use smooth, even strokes from side to side.
5. Continue grinding until you have established an even, sharp bevel along the edge.
6. Turn off the grinder and carefully feel the edge. Repeat grinding if it is not razor sharp.
7. Release the chisel from the honing guide and polish the edges by stroking them along the leather honing wheel charged with compound.
8. Wipe the blade clean and test the edges. Carefully feel for any remaining burrs and polish them away as needed.

It’s important to frequently check your progress as you grind. Turn the grinder on and off to regularly inspect how the bevel is forming. Go slowly and methodically while maintaining your angle.

Take extra care when sharpening narrow mortise chisels. Grind only on the corners at the tip to prevent overheating the thin blades.

Honing on a leather wheel with compound can refine the edge to an exceptionally sharp finish. Just a few light strokes is all that is needed.

Tips for Successful Grinding

Follow these tips to master sharpening chisels on a grinder:

• Use a coarse grit wheel – Soft Arkansas wheels may overheat the edge. Stick with an 80-120 grit wheel.
• Check the wheel for roundness – Dress the wheels if they appear out of round or show grooves.
• Go slow – Do not press too hard. Use light pressure and smooth strokes.
• Cool often – Dip in water every 5-10 seconds to prevent overheating the edge.
• Maintain your angle – Use a honing guide for consistency.
• Use a light touch when finishing – Just a few passes on the leather wheel is all you need.

With practice, you’ll be able to quickly restore a sharp edge on your bench chisels. Take your time and don’t overheat the steel. The grinder can be your best friend for chisel sharpening.

Troubleshooting

Here are some common problems and solutions when sharpening chisels on a grinder:

Problem	Solution
Overheated edge	Cool more frequently in water. Use lighter pressure. Consider a finer grit wheel.
Rounded bevel edge	Maintain proper sharpening angle. Dress wheel if grooved.
Burr on edge	Strop edge on leather wheel to remove burr.
Dull finish	Use honing compound on leather wheel.

Avoid overheating above all else. This can ruin the temper of the steel. If you see a blue tint or straw color appear, you’ve overheated the edge. Allow the chisel to cool completely before attempting to sharpen again.

When to Use a Grinder vs Whetstones

Knowing when to use a grinder vs whetstones comes down to the condition of the edge:

• Use a grinder – When there are chips, gouges or heavy wear. A grinder quickly repairs significant damage.
• Use whetstones – For quick touch-ups and maintaining an already sharp edge. Whetstones offer more control.

A coarsely ground edge can also be refined to a polished finish using a series of ever-finer whetstones. Use your judgment – let the condition of the edge dictate which sharpening method to use.

Grinding Wheel Grits

Different grinding wheel grit sizes work best for certain sharpening needs:

• Coarse (36-60 grit) – Heavy stock removal, severe damage repair.
• Medium (60-80 grit) – General sharpening, moderate stock removal.
• Fine (120-180 grit) – Light sharpening and polishing.

A good all-purpose grind wheel grit for chisel sharpening is 80-120. Go coarser if the edge requires extensive repair and shaping. Or use a finer wheel for final polishing.

Grinding Wheel Composition

There are three common grinding wheel bond types:

• Vitrified – Glass-bonded. Used with water. Best for chisel grinding.
• Resinoid – Resin-bonded. Used dry.
• Rubber – Flexible rubber-bonded. Used dry.

Vitrified glass-bonded wheels are the best choice for chisel sharpening. They stay flat and cut aggressively. Resin and rubber wheels are better suited for grinding tools made from softer materials.

Grinder Speeds

Generally, lower grinder speeds are better for sharpening chisels. Higher speeds tend to overheat the edge.

Ideally use a grinder that allows you to shift between lower and higher speeds. Run at the lowest speed that still cuts efficiently.

If your grinder only operates at one speed, stay alert and cool the edge frequently to prevent burning.

Grinding Wheel Dressing

As grinding wheels are used they slowly wear down and can develop grooves or depressions. Using a dressing tool periodically trues and resurfaces the wheels so they run perfectly round again.

Diamond dressers are a quick, convenient way to dress grinding wheels. Hold the dresser firmly against the spinning wheel to smooth and flatten the abrasive surface.

Well-dressed wheels sharpen tools much more accurately and effectively.

Grinding vs Honing

Grinding and honing are two distinct stages of the sharpening process:

• Grinding – Reforms the primary bevel using coarse abrasives. Fast metal removal.
• Honing – Refines and polishes the edge. Very light metal removal.

Grinding repairs chips and damage while honing smooths out any burrs and creates a razor sharp edge. Both stages are critical to achieving perfect sharpness.

Conclusion

Knowing how to sharpen chisels on a grinder is an invaluable skill for woodworkers. With the right methods, this quick approach can restore a razor-sharp edge with ease.

The keys are using the proper grit wheel, maintaining the correct angle, cooling frequently, and finishing with a light honing. Master these steps and you can sharpen chisels like a pro.

So grab those dull chisels and put your grinder to work. You’ll gain a renewed appreciation for how quickly this tool can breathe new life back into a worn edge.