As we’ve mentioned in an earlier post, woodcarvers generally either love or despise a skew chisel; very few are ambivalent about the tool. Those who dislike the skew chisel frequently complain that it’s tricky (or nearly impossible) to sharpen well.
This post addresses the fine points of sharpening a skew chisel. We’ll cover the factors that affect how quickly your skew gets dull, when to sharpen it, and how to sharpen it. Along the way, we’ll provide tips and tricks that make the job easier.
What factors affect how quickly a skew chisel gets dull?
Here are the big things that affect the sharpness of a skew chisel. Combine two or more of them, and your skew chisel can get dull in only 15-30 minutes of actual turning time.
The quality of the steel in your chisel
Craftsmen disagree about which type of high-speed steel makes the best skew chisel blade--M2, cryogenic, M42, PM, or something else. They agree, though, that 1) some high-quality steels hold their sharpness longer, and 2) poor-quality steel dulls quickly.
The wood you are using
Hardwoods dull a blade faster than softwoods do. The moisture in green wood makes it easier to cut than kiln-dried wood and extends the life of a cutting edge. Knots, twisted grain, or other defects in the wood increase the frequency of the need for sharpening your skew chisel. And, of course, any dirt on the wood makes the blade work harder and means that it will need more frequent sharpening.
The amount of wood you are turning with your chisel
This doesn’t relate simply to the size of the project, although size is a factor. What’s also pertinent is how much excess wood you start with in a particular piece. If you saw your woodblock as close as possible to the finished dimensions before you start turning, your skew chisel will cut through less wood and stay sharp longer. If, however, you start with a piece that’s a bit wider than you need it to be and use the skew chisel to trim the excess, your blade will dull quicker. (Woodcarvers who use and sharpen skew chisels expertly sometimes opt for this method. They find that increased sharpening time is more than offset by the efficiency with which the skew chisel chews through the excess wood. )
How will you know when your skew chisel needs sharpening?
Once you become accustomed to woodturning with a skew chisel, you won’t have to keep an eye on your watch or track your actual lathe time to know when to sharpen your skew chisel; it will tell you. Here are some signals that your skew chisel needs sharpening:
Your chisel isn’t cutting smoothly.
A sharp skew chisel blade cuts through wood efficiently and quickly, and yields a smooth finish that requires little sanding. As the blade dulls, it no longer produces that same smooth finish. When you notice a rougher texture or slight imperfections in the finish, it’s time to sharpen your chisel.
Your chisel isn’t cutting easily.
As your blade dulls, you must apply more pressure to get the skew chisel to cut through the wood. When you’re working harder, your blade is, too. You need to take a break and sharpen your tool.
You’re getting wood chips rather than wood strands as “sawdust.”
Lathework yields “sawdust” that’s in the form of distinctive wood strands rather than tiny bits or chips. As we mentioned earlier, when the blade of your skew chisel dulls, it will not cut through the wood smoothly. This results in wood chips rather than strands and signals a dull skew chisel blade.
Your chisel is singing a different tune.
As your tool cuts through the wood, it sings a distinct song. The exact tone will vary from piece to piece, depending on the type of wood you’re using. However, as the skew chisel’s blade dulls, the tune changes a bit. This change signals a dull blade that needs sharpening.
What’s the best way to sharpen a skew chisel?
That’s a loaded question! Ask 5 woodturning experts the best way of sharpening a skew chisel, and you could get 5 different answers. Some recommend using a grinder or a grinder fitted with a special sharpening jig. Others swear that a diamond cutting stone, a honing tool, and a bit of arm strength are sufficient to produce an excellent cutting edge. We’re not going to recommend one method over the others. All of them work well with practice.
Fortunately, the experts agree on several things:
Regular sharpening is crucial.
Dull tools make you work harder and yield inferior results. If your skew chisel is dull, you’ll spend more time at the lathe and significantly more time sanding.
The bevel angle may vary a bit, but should be within a certain range.
A few experts are quite adamant that the bevel angle should be 30°. Most agree that an angle in the range of 30°-40° is optimal, depending upon the specific skew chisel, its blade shape, and its size.
A black Sharpie marker helps you see any defects with your sharpening technique.
Mark the bevel on one edge of the blade with a black Sharpie marker. Sharpen the blade for a bit. Check the bevel area; places where the black marker is still visible indicate sections that are not being sharpened.
If you use a grinder, you shouldn’t put pressure on the skew when you lay it against the grinding wheel.
A firm touch and a steady horizontal movement across the grinding wheel will suffice. Pressure will result in uneven sharpening along the bevel.
Safety goggles are a good idea, especially if you are using a grinder.
Grinders can send tiny bits of metal flying right toward your eye. Protecting your eyesight is just smart.
Hone as a final step to remove burrs and put the final touch to an excellent sharpening job.
Removing burrs is essentially the finishing touch without which the job isn’t quite complete.
- Several factors affect how quickly your skew chisel will need sharpening. Knowing what those factors are helps you anticipate how long your skew will stay sharp.
- Your skew chisel will tell you when it’s getting dull. Listen to what it’s saying.
- Experts disagree about which sharpening method is best. The fact that each method has its fans means that each one works well once it’s mastered. You need to find a way that works consistently well for you and use it regularly.