Blade Shapes, Application, and Durability

How thick should a blade be, and how wide should it be?  How heavy should it be?

Obviously, this question is relative to the intended use. For example, a rapier blade may be as thick as it is wide, for a major portion of its length. A blade of this type is pretty much intended for piercing only, like an awl or icepick.

The leather awl is a small, thick blade, usually having at least two, maybe 3 or 4, sharp edges.

A dagger, again intended for piercing, is generally thinner to facilitate limited sideways cutting. It might be an inch wide, and an eighth- to quarter-inch thick, with symmetrical double edges. Being double-edged, only half the blade width, or less, can be occupied with the bevel angle. This blade can be used for a certain amount of slicing and other sideways cutting, but is still a bit thick for accomplishing significant amounts of work.

Years ago, I got a Gerber LMF knife (different from the new LMF II, but similar to the more recent Steadfast model) for outdoor woods use. It was a nice strong knife, 1/4 inch thick, with 5/8-inch-wide bevels. If sharpened across the entire width of the bevel to a “zero edge,” it cut quite well. However, it was a poor choice for long-term utility use, because so much steel had to be removed every time it was sharpened, in order to maintain a reasonably efficient cutting angle. But, if kept for emergencies only, it would be a reasonably good utility knife, as well as an outstanding weapon.

Randall knives, and many of the SOG blades, are a little thinner geometry than the Gerber LMF. Again, great knives for a man who might be in the army for a couple years, and then use them for a week or two per year in hunting camp.

Now, let us turn our attention to the primitive world–the old American frontier, and rural areas of most less-developed countries.

A few years ago, I had the privilege of traveling nearly the full length of Mexico. The cutlery in common use was highly interesting. I did see a few specialty blades, such as scoops for harvesting agave. But most everything was done with two types of blades.
One of these blades, was a butcher knife, stainless steel, about 6 inches long. (Colonial brand is the main one I remember seeing.  It’s different from the Rhode Island firm.) It seemed to do all the jobs where a smaller knife was needed. And, the Mexicans sharpen the knives VERY thin. It was common to see serious chunks missing from the edges, but this did not deter the people from keeping the edges thin.

(This reminds me of when I first discovered the concept of “grinding an axe” in the book Wildwood Wisdom. So, I promptly took a cheap hatchet to the belt-grinder and hollow-ground it–really thin. Shortly thereafter, we went camping, and I was having lots of fun chopping with it. It cut so nice now! Then, I happened to look at the edge, and noticed that a chunk the size of half a 25-cent piece had broken out of the edge. But the axe was STILL cutting better than before I thinned the profile. Lesson learned. Convex-grind axes, don’t hollow-grind. But, keep the angles thin!)

Again, let us call to mind the American frontier. What were the most common blades? I. Wilson, Russell “Green River,” and similar thin-bladed knives, not much different from the do-all blade I saw everywhere in Mexico.

Most were 1/16 or 3/32 of an inch thick. Not super stiff for thrusting, but you could use them until they were sharpened down to a nubbin, without having to remove heaps of metal at each sitting.

And the other knife in common use in rural Mexico? Machete!

Again, a knife that is intended for maximum thinness. THIN = EFFICIENT. THIN = EASY SHARPENING. And these were no short blades. 27 inches was very popular, with a wide double-edged tip. Most were about 3/32 thick at the handle, and thinner nearer the point. It was very rare that people bought short machetes, because there were so many worn out ones that got short after a few hundred sharpenings. In cleaning up a friend’s yard, we found lots of these worn-out machetes, and old 3-sided files, among the leaves and rocks. And quite frankly, we could have put them to work in a pinch.

So, where is the balance?

For a soldier’s knife, something like a Randall Model 1 is quite good. For woods use, I still like a belt knife that has some weight forward for chopping, but has thinner, wider bevels for durability and long sharpening life; while maintaining more stiffness and strength than a kitchen knife.  Thus, my standard models of handmade knives.

A final point here, is weight.  How heavy should the knife be?  Backpackers often want something super-light, yet strong enough for actual work.  On the other hand, an old-time logger might be happy for an axe with a 4- or 6-pound head, simply because it can do so much work with a single blow.  Weight tends to dampen shock and vibration which fatigues the hands and arms.  But it also slows motion.  For light chopping and rapid cutting strokes, too much weight slows things down.

One example of weight versus performance, is with a shovel.  We all like to have dependable tools, and a heavy, strong shovel will last longer than a light thin one.  But, for actual production, light shovels are much better.  (Which is why we like aluminum and even plastic shovels for sawdust and fluffy snow.)

For example, let’s say our shovel weighs 4 pounds, including the handle.  Now, our average scoop of material might weigh 12 pounds.  So, we must pick up 16 pounds and swing it.  Then, we must suddenly stop the movement of 4 pounds, and bring it back to the starting point, as the payload flies away–we hope!  (Otherwise, catching all 16 pounds can about take the shoveler off his feet if he isn’t ready).  So, in this case, 40% of our effort is spent in moving the shovel, and 60 percent in moving the payload (not including the effort to get the shovel under the load).

If we increase the weight of the shovel by one pound, we are now spending 45% of our effort on swinging the shovel.  If we were to double the weight (which would not be far-fetched when comparing a steel shovel to an aluminum shovel,) we would be spending 57% of our effort swinging the shovel.

Quite frankly, there are times to use that extra-heavy shovel–usually, because the lighter shovel will be destroyed by the stress of digging in harder materials.  But if we are shoveling fluffy snow?  NOT!  The person we are shoveling for would be wise to buy us a light shovel so we will get the job done faster, and get off the clock!

Similarly, with a hoe.  (And the hoe is a better comparison to a knife.)  If we are hoeing in loose soil, with weeds a half-inch tall, we need a light, thin hoe that we can move back and forth very quickly.  But if we are dealing with a thistle-patch that is about to go to seed, we need a heavy grub-hoe that can penetrate stems, roots, and relatively hard ground.  If we try to use the wrong hoe for the job, we will need to put forth a lot more effort, and using a light hoe for the heavy digging might destroy both the hoe and our hands and wrists.

One interesting comparison, is between the Ontario Kukri (12-inch blade, 1/4-inch thick) and the Cold Steel Kukri Machete (13-inch blade, 1/8-inch thick).  The Ontario is heavier, and short enough to fit in a daypack.  The Cold Steel is not so pack-friendly, but a bit lighter.  Yet, it out-chops the much-more-expensive Ontario.  So, for use around the farm, I go for the Cold Steel.  But for my every-day go-bag, where weight is not a huge issue and I may wish to carry on the belt with the leg-strap, the Ontario wins.  A third tool to seriously consider, is the PTS Bush Knife.  It gives up a lot of inertia, but is amazingly powerful and comfortable to use when compared with the others, at minimal weight and bulk, and long sharpening life.  Check it out here on the blog.

So, take your pick of the fabulous selection available in the world of knives today. Something out there is well-suited to your application.

Advertisements

About christophersknifeblog

I am a knifemaker and dealer, and live a very diversified life in the mountains of central Idaho. I love nature, agriculture, and homesteading. My knifemaking motto and advertising slogan is, "Knives Built for the Bush." I intend them to be efficient, durable, comfortable, functional, graceful equipment for life's challenges and opportunities. My website is www.ctfischerknives.com. Please visit!
This entry was posted in Knife-related Information and Philosophy and tagged , , , , , , , , , , , , , , , , , , , , , , , , , , , , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s