The most important part of any wood work is a good sharp tool. A sharp tool makes the work quicker and easier, more precise, less prone to error, and safer. Now, it does take time to properly sharpen your tools, but if you don't, you are going to be disappointed with your results and will end up working harder than you needed to work. If you are just starting out in wood working, you are probably still doing things the hard way with a dull tool. In this little essay, I will endeavor to help you produce a properly sharpened chisel or plane since these are the most common edged tools.
A sharp edge is theoretically pretty simple. You need two intersecting planes. Generally, the smaller the angle between the two planes, the sharper the edge and easier the cut. The smaller the angle, though, the less force it can take without folding over or blunting. Consequently, the harder the material you are going to cut, the greater the angle of the two intersecting planes needs to be. An edge to cut hardwoods needs to be a little greater than an edge to cut softwoods. For our purposes, lets shoot for edge around 25-30 degrees. I know that some people obsess over angles and such. Close is good enough. How you grind or stone the edge is generally much more important than the exact angle.
The most important thing about getting a really sharp edge is that the intersecting planes must be as perfect as possible and highly polished. If your edge isn't polished like chrome, it isn't sharp. This is why you start with course stones and finish with very fine grit stones. I say stones because that is what most people use, but you can also use sandpaper glued to a sheet of glass. The principle is the same. You can start with a 200 grit wet dry sandpaper and end up with 1000 grit sandpaper. The last step in all sharpening is honing on a leather strop.
If you use stones, at the very minimum, you are going to need a set of soft and hard Arkansas multiform stones or slips. These can be used to sharpen flat chisels and small plane blades as well as gouges; but I would also add a Washita, soft Arkansas, and hard black Arkansas bench stones. All these stones are used with mineral oil to carry away the small bits of metal. You can also get wet stones that are used with water, as well as new diamond impregnated stones. No mater what type of stones you use, you will need a leather strop. I suggest that you get a thick piece of leather about 4-5" wide and 10-12" long and glue it to a piece of scrap wood. Some type of fine abrasive dressing is recommended for the strop. I sometimes use white rouge, but a little lapping compound will work.
The quickest and easiest way to get a good edge is to get the Tormek sharpening system. This is what I now use. At about $400 for the basic system, it is expensive, but if you use a lot of edged tools on a regular basis, it is worth the cost. The system includes a large, low RPM, water cooled wheel with a rotary leather strop. The wheel is normally 200 grit and can be re-graded to 1000 grit. There is an adjustable tool rest and all sorts of special jigs for the precise sharpening of every conceivable edged tool. However, the only accessory that I think you need for gun work is the profiled, leather honing wheel. While I have a Tormek and highly recommend it, I will go over how to use standard bench stones to sharpen plane blades and chisels.
Plane Blades and Flat Chisels
Plane blades and flat/straight chisels are both sharpened the same way and are pretty simple. The first thing you need to do with these blades is flatten the back and get out all the milling marks. Now, you really only need to grind the area just behind the edge. I would say that if your get a half an inch polished up behind the edge once you are done, that would be good enough, but you are going to want to work on an area the width of the stone you are using. Start with your coarsest stone and move the back of the blade near the edge around on the stone in a circular pattern. Make sure you keep a good bit of downward pressure on the blade to make sure it stays flat on the stone. Use the entire width of the stone to grind the blade, and move the blade around the stone so that you don't wear a depression in one spot. I should warn you that this is going to take a while, but you only have to do it once for each blade. This is one place where the Tormek is so nice; you can use the side of the stone for flattening. Once you have ground out all the machine marks, move to the next highest grit stone until you have a smooth surface. You can polish the back on a strop.
Once you have the back flat and polished, now it is time to grind the bevel. You can do this free hand or you can use a jig to hold the blade at the desired angle. If you do this free hand, you need to hold the angle steady and keep a good deal of down pressure on the blade to make sure you keep the bevel flat on the stone. Remember it is important that the bevel be a flat as you can make it. This is what is so great about a slow speed grinder like the Tormek. It is easy to hold the blade at the exact same angle while the stone is turned under it. It is much harder to hold a blade and move it over a stone at the same angle for the number of strokes needed to grind the bevel.
As an alternative, you can position the blade on its side on the edge of the bench and move the stone against the blade, holding the stone like a file. The stone would also ride on the edge of the bench. This is the best way I have found to use a stone to sharpen a gouge, but it can also be used on a flat chisel and possibly a plane blade. However, it might be best to use a jig with a plane blade and keep the stone flat on the bench.
No matter how you physically hold your blade and stone; once you get a nice flat bevel, move on to the next highest grit stone, polishing the bevel finer and finer. When you have finished with the hard black Arkansas stone, you should have a pretty sharp edge except for the wire edge burr on it. You will knock this burr off with the sharpening strop. You want to pull the blade along the strop perpendicular to the edge, at an angle slightly greater than the bevel with a lot of down pressure against the edge. What you are doing with the strop is pulling off the wire edge and polishing the edge of the bevel. Pull the edge along the strop in several long, quick strokes until the blade starts to warm from the friction. You should have a brightly polished edge at this point. Safely test the sharpness of an edge by lightly touching the edge to the back of your thumb nail. If the edge is properly sharpened, the blade will stick to your nail. If the edge is not properly sharpened, the blade will slide off your nail. In that case, go back to the black Arkansas and start over.
You can use this same procedure to sharpen knife blades and double bevel chisels. The only difference is that you have two bevels instead of a bevel and a back. You use a circular motion on the stone to grind the bevels taking care to use the same number of strokes on each bevel. Remember to keep pressure on the bevel to keep it flat against the stone. You then finish up on the stop taking a few strokes on one bevel and flipping over the blade and taking a few stokes on the other bevel.
While the basics of sharpening are the same for gouges, there are a few added complexities. First of all, you have a curved bevel and back to grind. This means that you have to roll the bevel relative to the stone as you take your strokes, but we are getting ahead of ourselves. You still have to grind the back smooth. For a gouge, the back of the chisel is the inside or top edge of the blade. The bevel is on the outside or bottom edge of the blade. Now, the blade is ground the opposite way for some arts and crafts carving, but for traditional gun stock carving, the bevel is on the bottom so that you maintain the radius of the blade at the edge.
You might be asking, why is that important? Well, for traditional, 18th century, Rocco carving, you should be using European numbered chisels. The numbers represent the relative radius of the blade as a segment on the golden mean derived volute. The golden mean derived volute can be thought of as the increasingly tightly spiraling line of the Nautilus shell. A #1, or flat, chisel is at the beginning of the spiral. A #11 gouge, or veiner, with a very small radius represents a segment at the center of the spiral. All the other gouges lie in between. You form a proper Rocco "C" or "S" scroll by using increasing and decreasing number chisels in sequence. The radius represented by the number is ground on the inside of the blade. It is for that reason that you have to grind the bevel on the outside edge in order to maintain the proper radius of the chisel.
That said, what does that mean for grinding the back of the gouge blade? It means that you hold the best fitting rounded edge of your multiform stone slips firmly again the inside surface of the gouge while stroking along the blade. You stroke back and forth along the blade, moving the stone from one side of the blade to the other. Remember, that at all times, the long edge of the stone must be firmly against the blade using the blade as a guide. You will stone first with your soft Arkansas stone, then with your hard Arkansas stone. You should remove all the machine marks leaving you with a smooth, uniform surface near the edge. You will strop later.
Now it is time for the bevel. The best way to do the bevel is to use a full size bench stone like a file as briefly described previously. Since I am right handed, I hold the bench stone in my right hand with the edge resting on the edge of the bench. With the left hand, I hold the gouge by the handle with the blade also resting on the edge of the bench so the I can easily rotate the blade from one side to the other. I then bring the blade and the stone together so as to form the bevel at the proper angle. Once you have the right angle between the gouge blade and the stone, you use the edge of the bench to help you hold the angle. Then it is just a matter of moving the stone back and forth over the edge of the bench while turning the gouge blade evenly from one side to the other in order to get an even bevel. As with the other types of edges, you start with your coarsest stone and move systematically to the higher grit stones using the method described above to grind the bevel.
Art & Mysteries of the Craft
Once you get to the hard Arkansas stone, you might think from previous experience that it is time to strop. Well, there is another step required of sharpening carving chisels that I haven't told you about. Actually you need to go back and perform this step on all your flat chisels that you use for carving, particularly the double bevels. You need to grind a very small bevel at the end of the bevel you just so carefully ground. This is not a big bevel, just a few licks with the hard Arkansas stone until you can see another bright edge. The final bevel should just be a few degrees greater than the initial bevel. The reason for this bevel is to give you a little heel to use for leverage to keep from taking a deeper cut than you want. Without the heel, it is difficult to control the tool. You grind this same type of heel on gravers for the same reason, but that is another essay.
When you have finished the second bevel using the hard Arkansas stone, then, it is time to strop. You will need a wide, thick piece of leather as described previously. It may be easier to use if you glue it to a piece of wood but that is not necessary. We will start by stropping the back of the blade. That is done by pressing the back of the blade down into the leather hard and pulling it from one end of the strop to the other. As you pull the blade along, the blade will cut down into the leather forming a convex groove that will fill the back of the blade. Keep stropping the blade until the back edge of the blade is polished bright.
Next, we will stop the bevel. Use the chisel to cut a concave groove next to the convex groove. Once you have cut a groove from one end of the strop to the other, pull the bevel through the groove from one end to the other at an angle slightly greater than the bevel. Keep stropping until the blade starts to heat up. You can stop when you have a bright shinny edge.
When cutting the convex and concave grooves in the strop, you don't have to cut one for every gouge. You will find that you can use the same set of grooves for several similarly sized blades. You just have to press down hard so that the leather conforms to the blade. While some people don't use any sort of abrasive on their strops, I do. I use some white rouge or the honing paste that comes with my Tormek. By the way, the profiled honing wheel on the Tormek takes the place of cutting grooves in a flat strop.
While I have described in this essay how I actually sharpen my plane blades and chisels using stones, I didn't develop these procedures on my own. I must give a great deal of credit to Wallace Gusler, Mark Thomas, and Jim Chambers for their instruction. Wallace Gusler shows how to do all this in his video, Relief Carving a Kentucky Rifle (circa 1775). The Gusler video made all the difference in my ability to properly sharpen chisels. Using the stone as a file, as shown by Gusler in his video, was a revelation for me. Mark Thomas and Jim Chambers added to my knowledge through seminars at the Dixon's Gunmakers Fair and the Armsmakers Workshop at Conner Prairie, respectively.
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This page was last updated on 11/22/03 .