Is There a Perfect Blade Grind?
Who knows when the first argument over the best blade grind started? Most likely it was a conversation between two flintknappers sitting around a cave—and the battle of which grind is the best rages on to this day. The modern tactical and bushcraft movements have brought heated debates on which grind is the best. The grind of a blade is where a key battle is won, and blade geometry varies widely. But is there a so-called best blade grind and, if so, which one is it?
Curved or Flat?
According to Wikipedia, blade geometry refers to the “physical properties of a sword blade: cross-section (or grind) and taper.”
You can forget the “sword” qualifier—blade geometry applies to any blade. The three most common blade grinds in use today are hollow, flat and convex, with other grinds of note are the chisel, asymmetrical, Scandi and compound. There are others.
Before becoming a renowned custom knifemaker, Walter Brend was a meat cutter, the skills of which gave him keen insight into the art of the slice.
“What works for me is the hollow grind,” Brend says. “The hollow-ground blade is not a flat surface, it is concaved, so as you cut an object it immediately starts a separation. The bottom edge should flow from the point to the back of the blade with a recurved blade edge.”
Knifemaker Bob Dozier, well known for making hard-use knives, prefers the hollow grind as well.
“Since I make mostly hunting knives, I prefer the drop-point blade style. Since Bob Loveless popularized the drop point, it’s been the most popular shape for hunting knives for many decades now. Also, for a hunting knife, the hollow grind is the best as it stays thin at the edge much longer.”
However, that’s not to say Dozier is adverse to other grinds.
“The flat grind is the best for the kitchen as it does not wander when making thin slices,” he opines. “A convex grind is great for splitting firewood.”
“My opinion for the best blade geometry is a full flat grind with a convex edge,” Crowell begins. “This grind will give the smoothest transition from the full thickness of the spine to the cutting edge—anything else is something less.”
Crowell is also very familiar with the Bill Moran appleseed or convex grind, which is based on the Japanese hamaguri or “clamshell” grind.
“Bill Moran did like full convex blade geometry,” Crowell notes. “He ground on a round wheel and meticulously shaped the whole blade to have a convex cross section. I have cut with several of Bill’s knives and they were very sharp and had great geometry.
“The full convex grind performs in an exemplary manner, but I cannot discern any advantage in performance over a full flat grind with a convex edge. You do not just slap a convex edge on a blade. There are a myriad of variables: how thick was the edge when you started the roll? How high or low did you roll it? A short and abrupt roll may shave but will not cut well at all.”
Degrees of Difficulty
Curious as to the degree of difficulty of applying the various grinds, BLADE® asked Brend, Dozier and Crowell which they thought are the most difficult to execute. They provided varied opinions.
“I think whichever one you do the most is easiest, and the one you do the least is hardest,” Crowell notes. “Once upon a time I used to hollow grind a lot, but then I started to cut a lot and it became apparent to me a flat grind would cut better overall for my use. I gradually phased out hollow grinding and now find it difficult as compared to flat grinding.”
Dozier adds pointedly, “I don’t find any of them hard. I think it depends on how you learn to grind at first. A lot of the makers today learned from someone else and stick with the grind they learned.”
Brend ranked the grinds in order of difficulty.
“Hollow-ground knives, in my opinion, are the hardest to grind,” he begins. “You have to control the blade on a wheel to form a perfect symmetrical line. In my opinion you should keep the point thick, and, at the same time, make your edges sharp and thin.
“Flat ground is next after hollow. In my opinion a true flat-ground blade should be finished by hand because the grinding belt will not allow a true flat surface. Convex is the easiest because you have no set lines or pattern when grinding.”
Order of Importance
Is blade geometry the most important aspect of a blade’s cutting effectiveness, or is the type of steel or proper heat treating most crucial?
“The most important is blade geometry,” Dozier says. “The type of steel and how it is heat treated has nothing to do with how it cuts, only how long it cuts.”
“Heat treat, geometry and steel, in that order,” he opines. “If the heat treat is wrong, the rest will be of little consequence. Proper geometry is next in importance. The steel, although important, is not the determining factor. Of course, you need to have a ‘good’ steel, but it is not the steel that makes the difference. Just because you may have the latest, greatest steel does not mean you will have a superior knife. You have to do it all correctly and in the right order.”
Brend ranks the three differently.
“I think the type of steel is the most important. With proper heat treating you can vary from two-to-four points [on the Rockwell hardness scale] and still cut with the knife because of the type of steel,” he says. “Heat treating is second. With most steels you can be within two points and still cut with the blade. All heat treaters are not the same because of the equipment or their method. Geometry would be the last because if you use the proper steel, you should be able to make any blade work well.”
Finally, what makes a bad blade grind?
“What I look for are the grind lines,” Brend explains. “Are the sharp edges of lines rolled? Also, at the back of the blade—where the [grind] line starts—is the steel uneven? I see some hollow grinds where the edges are too thin. If you hit a hard object the blade will chip.”
Opines Dozier: “A poor grind is shown with uneven grind lines, crooked cutting edges or a non-uniform cutting edge.”
“Poor grinding is evidenced by several telltale signs,” Crowell interjects. “Uneven grind/plunge lines as one would look from the bottom of the blade. This is one of the more obvious and common things to look for. Also, the finish on the bottom of the ricasso and choil area is often neglected. You can hold a blade horizontal and look down the flat of the bevel and it should be smooth as glass with no ripples or distortions.”
Jim also notes that on symmetrical patterns such as daggers, look for mirrored-image grinds on both sides of the blade.
One interesting takeaway: The perfect grind may just be determined by how you plan to use your knife—or perhaps you may need two or more knives to cover all the bases.