Sharpening for carvers
Until a carver finds “the method”, hours of extra hard labour and frustration are inevitable. Ultimately, many people simply stop carving because their tools just don’t work.
After years of practice and experimentation, I have found a technique that is simple and effective. Moreover, it is based on logic. This is the theory: a flat bevel is essential to creating and retaining a sharp cutting edge. If a tool is sharpened with any rounded surface (ie. a wheel), no matter how great the radius, some hollow grind will result. The cutting edge will be very sharp initially. However, subsequent honing, intended to retain its sharpness, will actually blunt the edge.
By establishing a flat bevel, all subsequent honing will repeatedly refine the cutting edge without any blunting. I have found that a belt-sander with a suitable selection of belts works beautifully.
“Sharpening” is a process that actually involves three steps: grinding, sharpening and honing. Grinding shapes the surface of the tool. Sharpening removes major imperfections from the cutting surface. Honing establishes the final and desired cutting edge.
Modified 1 inch belt sander
When grinding, ensure the belt rotates away from the cutting edge
Begin by establishing a new cutting edge
A plastic guide helps you to see when you have obtained a 15 degree bevel
When grinding, ensure you retain a straight edge
Grinding is complete when tinfoil burr appears
Remove burr in wood block
Sharpen in “soft” area of 20 micron belt
Sharpening creates a finer cutting edge
Apply lots of pressure for honing
The surface of a sharpened gouge
Honing creates a highly reflective surface
Grinding a Shape
For many, the first action is the hardest. To see what you are doing, you must first blunt the cutting edge of the tool. Do this by pressing the tool vertically onto the belt sander. By doing so, a reflective surface is created. I sharpen my tools at an angle of approximately 15º and make a guide from a plastic margarine bucket lid.
Now that there is a visible edge, the goal is to grind it away at the desired angle until the flat, reflective surface disappears. I do this grinding freehand; however, it would be much more consistent to make a bracket upon which you could rest the tool and ensure a precise angle. When grinding, ensure that the belt is always moving away from the cutting edge.
For grinding, I use a 120 grit belt and apply very light pressure because this belt is quite aggressive. As soon as the reflective surface has disappeared, a burr that looks like a thin line of tin foil will be created (notice the grooves made by the 120 grit belt). To remove the burr on the cutting edge, thrust the gouge vertically into a block of wood and rock the tool to-and-fro. When the end of the gouge no longer reflects light and the desired cutting angle has been established, the grinding step is complete.
Remember: the goal is to remove the reflective surface – this requires careful and patient effort, flat tip while retaining the straight edge of the gouge – this requires care and patience.
Sharpening the Tool
The “sharpening” step refines the shape created with grinding, and establishes a finer cutting edge. I use a 20 micron belt for this purpose. In my belt-sander, there is an area between the flat surface and the pulley wheel where the sanding belt is unsupported. This is the area I use for sharpening. I hold the gouge perpendicular to the belt. Using light pressure, the coarse grooves made by the 120 grit grinding belt are removed and a much smoother surface is achieved.
Honing the Cutting Edge
With a flat bevel and a well-prepared surface, an exceptionally sharp cutting edge can now be established by honing. I use a leather belt thoroughly coated with green chromium oxide (jeweler’s rouge). For honing, you can use as much pressure as you like because the leather belt carries heat away and the tool will not overheat. The belt should be turning away from the cutting edge. The result is a highly reflective surface and a keen cutting edge. As a final step, I polish the inside of the gouge using a cloth wheel coated in chromium oxide.
A Final Word
You may have heard the expression “One is cut more often with a dull tool than with a sharp one!” This is true because a dull tool requires extra force to cut. Sharp tools will reduce your effort significantly, will give much greater control, will result in a better carved-surface, and will enable you to make the precise cuts you desire.