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Stay Sharp Wood Chisels Date: 1/23/2016 10:47:00 PM Wood Chisels With modern technology, many of the old school woodworking tools have become less used and often left to sit rusting on a shelf or hung on the wall above the tool bench. One tool that is still used by many craftsmen today is the wood chisel. Although many of the tasked once performed solely by the wood chisel can now be done with power tools, it is sometimes more efficient to just reach for the chisel to either make a shallow mortise for a hinge, or just to clean up the square corners in a recess. Wood carvers also continue to use the chisel when removing large quantities of material when not only forming the outline or shape of an object, but also in shaving areas with precision accuracy. They are easy to control, when used properly, and will leave a smooth clean cut when needed, while still being able to remove larger chips with one pass. Craftsmen will use their chisel to make fine adjustments to the work they are doing eliminating the need to take the piece back to the table or out of the area they are working to shave a little more material to get that perfect fit. In order for the chisel to function properly, the cutting edge must remain razor sharp. The sharper the better. This allows the user to be able to shave a fine amount of wood with very little pressure. The less pressure needed to push the edge through the material, the more it can be controlled. It also leaves behind a smooth surface that will need very little if any cleanup. Chisels are purchased either in sets, or singly. Even new they should be honed before they are used. Honing is the process of polishing the very edge of the blade to remove any leftover burrs from either production, or from use. Once they are honed to a razor sharp edge, they need to be carefully handled and stored to keep for cutting yourself as well as maintaining the edge. The handling of the tool is simply, never force the blade through the material and always push away from you while keeping hands and fingers out of the line of travel. Always handle it by the handle rather than the blade. The storage part of this is sometimes more difficult. In many cases they come either in a storage pouch, or they have a tip protector made of plastic covering the cutting edge of the blade. It is always good practice to return the blade to the protecting of either the case or the cover to keep the edge from becoming damaged if dropped. Even a short fall will nick or chip the cutting edge. When this happens they will need to be sharpened and honed to get the cuts needed in fine wood working. Unless the blade is damaged, a light honing from time to time will be all that is needed to keep them cutting like they should. Above is a picture of a chisel that had been dropped and abused. With the nicks in the cutting edge, it would be hard to get a clean cut in any type of wood. The bevel of this chisel is also much larger than it should be. This comes from using a bench style grinder and not following the original bevel angle. If not reconstructed, but just sharpened, this chisel would tend to dig deep into the wood, removing more material than you might want to remove. In most cases the bevel should be between 20 and 30 degrees. This one was more in the neighborhood of 42 degrees. Notice the dark coloring on the chisel on the left. At some point this one was sharpened on a bench grinder and it got too hot during the sharpening. Also notice that there are grooves left on the bevel from using a wheel that was too coarse. Since the heating would soften the material of the chisel, it would not be wise to sharpen it without taking it back past the discolored area. It would require a lot of grinding and time to repair this type of damage. Although it can be done, it would be easier and cheaper to just replace it at this point. Here the grinding was done and the edge was not kept square to the grinding wheel, again the wheel was too hard and left a lot of deep scratched that will need to be removed. Also the area closest to the cutting edge was ground at a totally different angle than the bevel, leaving a concaved, or hollow ground cutting edge. When honing a chisel, because only the very edge is polished, a secondary bevel will form over time. This is not bad until this angle becomes great enough to make it easy to shave the wood when needed. Then it would be time to have it sharpened and brought back to the proper cutting angle. Here you can see how the original bevel was ground creating a hollow ground face bevel. Many chisels do come this way, and some people say they stay sharper longer. Others would never use a hollow ground tool. It is personal preference. If you look at the cutting edge you will see a slight dark ridge along the center of the edge. This is where the chisel is actually dull. The very edge of the blade has worn from use, and needs to be honed. The slight difference from one side to the other can be taken care of in the honing process. The cutting edge can be squared off in this manner. When done properly the cutting edge of a sharpened chisel will be perpendicular to the side of the blade, giving a 90-degree angle at both corners. The cutting edge will be polished to a razor sharp edge allowing it to pass smoothly through the grain of the wood. The back of the blade will also be lapped to create a smooth flat surface. Although it is not real important to have a mirror finish on the full bevel, scratch marks from grinding should be kept to a minimum. This makes it easier to hone the edge as the tool becomes worn from use. When touching up the cutting edge of your chisels, use a honing stone wide enough to accommodate the width of the chisel. Start out with a medium to coarse stone and work down to a fine one. Keep the cutting angle straight across the blade as you work the burr off the edge. There are jigs that will aid in maintaining the angle and help keep things in line. The one you use depends on how comfortable you are with it. Some are easier to set up than others, but all follow the same principal, and it is a good idea to invest in one to help keep things sharp and safe. Remember the better the tools work for you, the more enjoyable your woodworking experience is going to be. The less chance there is that your mistakes will cause major problems, and the better the finished product will look. Many of the hand tool can be touched up in your own shop, it just takes a little practice and patience. When it comes time for a major sharpening, or you just can’t get it right, take it in and have it done professionally. You will find that your tools will be much more fun to work with. As always keep things sharp and Happy Cutting.