Spyderco byte June 2023 - EDGE-U-CATION® - Sharpening Serrations
Sharpening Serrations
Spyderco exhibits our products at many trade shows. One thing we frequently hear from people who visit our booths is that they are wary of purchasing serrated blades because they are too difficult to sharpen. In their minds, honing a serrated edge is like sharpening s chainsaw—a tedious tooth-by-tooth, scallop-by-scallop process. With the proper tools, however, nothing could be further from the truth.Our appreciation of serrated edges goes back to the earliest days of Spyderco, when company founders Sal and Gail Glesser traveled the country selling sharpeners, kitchen knives, and other gadgets at various fairs and shows. Among the knives they sold was the iconic “Ginsu®” serrated kitchen knife. Sal understood the extreme cutting power of a serrated edge, but he also knew making a serrated knife that offered a long service life meant offering an easy-to-use sharpener to maintain that edge. That’s why he designed the Tri-Angle Sharpmaker® well before adding serrations to our knives. As we say at Spyderco, First we made things sharp... Then we made sharp things.™
Sharpening Basics
The process of sharpening a SpyderEdge™ or any of the other serration patterns on Spyderco knives is fundamentally the same as sharpening a PlainEdge™—carefully remove enough steel at the apex of the edge to create the acute “V” shape that defines a sharp edge. In the process, you must ensure that the angles of this “V” are consistent along the entire length of the edge.Unlike plain edges, however, serrated edges present two unique challenges. First, serrations are generally only ground on one side. This asymmetrical “chisel-ground” geometry means the best way to maintain the integrity of their shape is to remove steel primarily on the beveled side of the edge. Also, to achieve true sharpness, the abrasive must contact the entire length of the edge—including the recessed scallops between each tooth. Ideally, this should not require the painstaking individual sharpening of each scallop.
Spyderco Sharpeners
Spyderco’s sharpening systems, including the Gauntlet™, Galley-V™, and Tri-Angle Sharpmaker, are all based on the classic “Crock Stick” design. This brilliantly simple approach uses two ceramic abrasive rods, each set at a precise angle to the left or right of vertical. By keeping the plane of the knife’s blade vertical and drawing the edge from heel to tip down each of the rods, the angles of the rods create the perfect sharpening angles for a symmetrical, V-shaped edge. This method is infinitely easier to learn than the traditional method of holding a blade at a specific angle to a flat stone and is easily mastered with just a few minutes of practice.The critical difference between the ceramic rods of the Crock Stick and Spyderco’s sharpeners is that, instead of being round in cross section, our rods are either triangular or an oblong “cat’s eye” shape. Equally important, the edges of both shapes have a narrow, rounded radius. This radius is carefully calculated to be smaller than the size of most serration scallops. By using this narrow surface of the rods as the contact surface, the same basic technique described above can be used to sharpen serrated edges quickly and efficiently.
Serrated Sharpening Technique
Before you begin sharpening a serrated knife, examine the edge closely. Most likely, you’ll find the terminal edge bevel (the bevel that creates the actual cutting edge) is only ground on one side of the blade. This is the “bevel side” of the edge. For most Spyderco knives, this is typically on the “obverse” side of the blade, or the left side when looking at the knife held edge down, point away from you.Repeat this process three times on the bevel side of the edge. This will reinforce the geometry of the serrations on that side and produce a slight “burr” on the opposite side of the edge. To remove that burr, move the knife to the opposite abrasive rod and make a single stroke against it. Again, keep the plane of the blade vertical, apply constant, light pressure, and draw the edge down the rod as you pull the knife toward you.
Return to the first rod and repeat the process again, alternating between the rods until you’ve completed five “sets” of three-to-one strokes. Examine your edge and if you have not yet achieved the desired degree of sharpness, repeat the process. It’s that simple.
You Gotta Have Grit
Coarse abrasives remove steel faster than finer ones do. Determining exactly what the coarseness of an abrasive is, however, isn’t as simple as it might seem. Conventional abrasives are graded based on “grit” size or “mesh.” Basically, meshes of a precise size are used to sift the abrasive during manufacturing. If it passes through a mesh of a particular size, it is categorized accordingly. As straightforward as this may seem, there are at least four different industrial grit standards used worldwide.>From Spyderco’s perspective, the concept of grit size only really applies to our diamond and Cubic Boron Nitride (CBN—a type of synthetic diamond) sharpeners. With these sharpeners, the abrasive is bonded to the outer surface of the steel “embryo,” so it is exposed to function like the grit of ordinary sandpaper. Most of these sharpeners, including the rods designed for use with the Tri-Angle Sharpmaker and Gauntlet, are 400 mesh (40-50 microns in size). Our double-sided CBN Benchstone is 400 mesh on one side and 800 mesh (14-28 microns) on the other.
Although diamond and CBN abrasives remove steel quickly, we do not recommend them for use on serrated edges. Since the abrasive grit is bonded to the rods, the focused pressure that occurs when sharpening on their edges can easily dislodge it. Once the abrasive is sheared off, it cannot be restored. Also, over time, both diamond and CBN rods can reduce the definition of the serration teeth. For these reasons, we only recommend our ceramic rods for sharpening serrated edges.
Ceramic abrasives are not graded in grits like diamond and CBN abrasives. In fact, the abrasive particles in all our ceramic stones start out the same size, about 15-25 microns. Their final coarseness is then carefully controlled through the other materials used in the ceramic (“carriers”), the firing process, and, in some cases, abrasive grinding processes used to achieve a final surface finish. However, by comparing the scratch patterns of edges sharpened with our ceramics to those sharpened by conventional abrasives, the following grit-size comparison may be made (based on the U.S. standard):
Depending upon the Spyderco sharpening system(s) you own, you can use this knowledge to expedite your sharpening of serrated edges. If a serrated knife is very dull, begin the process with a medium stone to remove steel more quickly and restore a working edge. You can then repeat the process with a fine stone to make the edge even keener. The best practice, however, is to maintain your serrated edges with regular touch ups using the fine rods.
Spyderco’s Tri-Angle Sharpmaker, Gauntlet, and Galley-V sharpening systems literally take the mystery out of sharpening serrated edges. Although they each offer slightly different sharpening angles and advantages, they are the quickest and easiest way to “put teeth” back into your serrated knives.