Spyderco byte July 2016
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Tri-Angle SharpmakerTM

MSRP: $104.95
    When Spyderco was founded in 1976, Sal and Gail Glesser were living out of a converted bread truck and traveling the country to sell knife sharpeners, kitchen cutting tools, and other products as “pitchmen” at fairs and trade shows. Selling other brands of sharpeners and serrated knives taught Sal a lot about what worked and what didn’t when it came to putting an edge on a knife, and he soon developed an idea for a significantly better sharpener design. In 1978 he made that design a reality, inventing the Tri-Angle Sharpmaker™ and setting a new standard in user-friendly knife sharpening systems.

    Traditional sharpening on a flat whetstone involves keeping the blade at a consistent angle as you draw the edge across the stone—an approach that requires considerable skill, extensive practice, and lots of muscle memory. Whetstones also require oil or water to keep the stone from clogging and cannot be used to sharpen serrated edges or blades with hawkbill or recurve profiles.

    The Sharpmaker solves all these problems and takes the guesswork out of the sharpening process by automatically setting the angles of the stones. All you need to do is keep the plane of your blade vertical as you draw the edge from heel to point. Maintaining the same grip and vertical orientation as you alternate side to side on the two stones ensures a consistent edge angle on both sides of the blade and quickly establishes a sharp, usable edge.

    The durable ABS plastic base of the Sharpmaker includes two sets of holes for the ceramic stones—one for a 40-degree included edge angle (20 degrees per side—perfect for most utility knives) and one for a 30-degree included edge angle (15 degrees per side for kitchen cutlery and other thinner blades). These holes are also specially shaped so the triangular stones can be oriented to contact the knife’s cutting edge either on the flat or the corner of the stone.
    For PlainEdge™ blades, either contact surface may be used; but for serrated edges, using the rounded corners of the stones is the way to go. By using the same basic technique and a slightly looser grip, the corner of the stone “flows” down into the concave sections of the serrations to sharpen the cutting edge along its entire length. Three passes on the bevel side of the serration establishes the edge and a single pass on the opposite side removes the burr to leave a sharp, highly capable edge. The rounded corners of the triangular stones are also ideal for sharpening blades with hawkbill or recurve profiles.

    Unlike traditional whetstones, the Sharpmaker’s alumina ceramic stones are designed to be used dry and do not require oil or water. Since they are significantly harder than most knife blades, they remove blade steel as they sharpen and will eventually clog with use. When this happens, simply clean them with warm water and ordinary kitchen cleanser to remove the steel and open their pores. Properly cleaned and cared for, they will last a lifetime.

    Out of the box, the Tri-Angle Sharpmaker package includes an ABS plastic base, a matching ABS cover/handle, two medium-grit stones, two fine-grit stones, two brass safety rods, a detailed instructional booklet, and a step-by-step instructional DVD that shows you how to use the Sharpmaker to sharpen almost any tool with an edge or point. In addition to the included stones, Spyderco also offers aftermarket stones for the Tri-Angle Sharpmaker, including diamond and CBN (cubic boron nitride) coated stones for rapid steel removal and ultra-fine stones to create hair-popping, highly polished edges.

    If you’ve ever struggled to put a sharp edge on your knife or been too intimidated to give sharpening a try, you owe it to yourself to get a Tri-Angle Sharpmaker. Still going strong after nearly 40 years, it’s the one tool that every serious knife user shouldn’t do without.

Understanding All the Angles

    The term “edge geometry” is one we hear a lot when discussing the cutting performance of knives. Although the geometry of the terminal cutting edge of a blade is certainly important, understanding real cutting performance means looking at “all the angles.”

    Edge geometry begins with the grind, thickness, and width of the blade and its bevels. For example, a full-flat-ground blade basically has a triangular cross section, with the spine of the blade being the base of the triangle and the two equal-length flat bevels forming the sides. If the planes of the bevels intersected perfectly at the edge (a “zero-ground” edge) it would be extremely acute and sharp, but very weak. Narrower blades, thicker blades, and shorter bevels would all affect the geometry of the triangle and increase the angle at the edge somewhat, but it would still be somewhat weak.

    To give the edge greater strength and make the blade easier to produce, the bevels typically don’t converge completely. Instead, they leave a thicker section of steel near the edge. A narrow secondary bevel is then ground at a steeper angle to create the actual cutting edge. The terminal thickness of the steel adjacent to the cutting edge is also a determining factor in the overall edge geometry of the blade.

    A full-flat grind with a thin terminal edge thickness creates a very acute angle near the edge and the long,  gradual rise of the bevels. This geometry parts the material being cut with minimal friction and offers excellent cutting performance. It also produces a distal taper that reduces the weight of the blade, but also decreases its strength.

    If strength is a concern, a partial flat grind—also known as a saber grind—can be used. With this grind, the flat bevels are shorter and the angle near the edge is slightly steeper. This puts more steel behind the edge, but also forces the secondary bevel of the actual cutting edge to a larger angle as well. This geometry parts material more abruptly and creates greater friction during the cut. 

    In many ways, a hollow grind offers the best of both worlds. Since its bevels are actually concave, it can produce a very thin terminal edge thickness and support an acute cutting edge angle, while still maintaining a thick spine for strength. Hollow-ground blades can also be sharpened many times before the edge wears into the thicker part of the steel. Flat-ground and saber-ground blades reach that point sooner and ultimately must be sharpened at a more obtuse angle.

    So what is the “best” sharpening angle for a knife blade? Well, in addition to understanding the geometry of its grind, you also have to take into consideration the type of steel from which it’s made. At a microscopic level, steel consists of a series of carbide clusters. The smaller these clusters are, the easier they can fit into the apex of a knife’s cutting edge to support an acute edge angle. For this reason, many Spyderco knives with broad, full-flat-ground blades made from steels with fine microstructures can be sharpened at a 30-degree included angle and perform just fine. That same sharpening angle and edge geometry with a coarse-grained steel, however, would be vulnerable to chipping at the edge. The large carbide clusters would literally break out of the edge because the angle is too acute. Such steels are best suited for a more utilitarian 40-degree included angle.
    Spyderco takes all of these factors into consideration when we produce our knives to ensure that every blade offers the best possible cutting performance within the scope of its design, blade material, and intended use. When it comes to edge geometry, we really do work all the angles.
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Spyderco Summer Picnic

    This month Spyderco took the time to celebrate our amazing Crew and their families by combining our annual summer picnic with a “Bring Your Kid to Work” day. This all-day event allowed the members of our Crew to share the details of their work with their children. It was also filled with special activities, including assembling plastic knife kits, learning about knife safety, designing ads, mastering BaliYo tricks, and lots of other fun things.

    Spyderco’s success is thanks largely to our awesome staff. As you can see from these photos, we thoroughly enjoyed taking a day to celebrate summer with them and their families!
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Spyderco, Inc.
820 Spyderco Way
Golden, CO 80403

800-525-7770 (T - Toll-Free)
303-279-8383 (T)
303-278-2229 (F)

Copyright © 2016. All rights reserved. All product names, art and text herein are the property of Spyderco, Inc. and may not be reproduced in part or whole without the sole written permission of Spyderco, Inc.

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Spyderco, Inc. · 820 Spyderco Way · Golden, Colorado 80403 · USA