How to Sharpen a Chisel
Learn to sharpen a chisel the easy way.
Chisel sharpening does not have to be a mystery to the woodworking beginner. Here are some steps for sharpening chisels:
1. Check the cutting edge for chips and straightness. If the edge is not straight it must be lightly ground until it is totally straight. When doing this, be patient. If you try to take off too much at one pass you can heat the metal too hot.
If the chisel is heated to a point where bluing colors appear you have ruined that area and it must be ground further back to remove this discolored area. Always go slow. Do not use too much pressure.
2. Once the cutting edge is straight across, you grind the angle. A safe grind angle for the average chisel is 25-30 degrees. Some people will do this free hand while others use a jig. Jigs can be made very easily. I suggest a google image search for ideas.
If you have to grind off the tip for straightning it will usually leave a flat end on the chisel. The new angle should not be ground with a common bench grinder. You need a belt sander or a wet grinder made for this purpose.
I use my 2x72" belt knife grinder. I rest my hand on the tool rest and eyeball it. I am careful to press it to the belt softly, gently and as straight as possible. I dip the chisel in water after every grind.
If the grinder has a speed control, slower is better. The slower the grind the less chance of overheating the metal. 300-400 grit belts work well.
3. Finish off the edge with a fine stone. Notice in the picture at the top of the page I am holding the chisel roughly at the correct angle. This works for most woodworking projects and especialy on a job. In the above photo I am holding the chisel almost flat and removing the burrs on the bottom edge. This is a very light swirling on the stone. I have had the best results with an oilstone.
If you want to get the chisel the very sharpest, try a buffing wheel to finish it off.
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