The complete sharpening sequence proceeds through a logical sequence of steps. However, every cutting edge does not necessarily need to go through the complete sequence every time it is sharpened. It all depends on the condition of the tool and the goals of the sharpener. The complete sequence includes these steps:
grinding to create the primary bevel,
honing to flatten the back of the blade,
honing to create the secondary bevel,
polishing, or stropping, the secondary bevel
and the flat back of the blade.
When to grind
If a tool is damaged along its cutting edge, it’s a candidate for grinding. Also, if a tool has been honed several times, it may need a little grinding. Sometimes a new tool has a factory edge that needs work. Other times, a chisel that will be used to chop deep mortises (see Figure 3) may need a larger angle than a bench chisel’s, achieved by regrinding its primary bevel.
Figure 1. The damaged edge of this chisel needs to be ground.
Figure 2. This new tool has a correctly shaped edge, but it is not sharp.
To create a secondary bevel on the front of a chisel, set a jig two or three degrees higher than the grind (for example, on a bench chisel go from a 25-degree grind to 28 degrees), and create the thin secondary. The quickest path here is to use diamond sharpeners for coarse, medium, and fine honing and switch to oil or water bench stones (see Figure 5) for very fine and extra-fine honing. The job is done when the secondary bevel is uniform and straight all the way across and a slight burr has been raised all the way across the back of the bevel. You can feel it with your fingers. The burr can be removed by honing the flat back of the blade on a very fine stone or by polishing.
When to polish
Polish, or strop, once you have made the secondary bevel straight and uniform, with a slight burr all the way across. Lightly touch the back of a cutter to a charged honing or stropping wheel to remove the burr (see Figure 6), and then polish the secondary bevel until there are no scratches. Note that polishing wheels move away from the tool (the tool is below the center of the wheel) while grinding wheels move toward the tool (the tool rest is above the axle). It is very easy to overpolish and make the edge dull, rather than sharp.
Figure 3. This mortising chisel is being reground to a larger bevel angle.
When to hone
Almost every tool that has been ground needs to be honed. The major exemptions are turning gouges, which are usually ground and then polished, and axes, which usually are left rough. On other tools, begin honing by flattening the back of the cutter (see Figure 4) while working through coarse, medium, fine, and extra-fine grits.
Figure 4. Flatten the back of the chisel on progressively finer bench stones.
Figure 5. Hone the secondary bevel, using a jig to maintain the angle.
Figure 6. Polish the edge by buffing on a charged wheel.