11 April 2009

EDC Knives: Knife Anatomy

With a title like “knife anatomy,” I virtually guarantee that no one will read this post. But I feel obliged to define the terms I will be using in future knife reviews (which I also expect no one to read). This introduction will not be anything like complete. For more info, see here and here.

Most tactical folders consist of a blade pinned to a handle composed of two steel inner liners to which outer coverings (scales) are affixed. The liners may be drilled out to lighten them (skeletonized), and some knives have no liners—the blade is just pinned directly to polymer or stainless steel scales.

Setting aside opening and locking designs, construction materials, and blade shape and grind (all later posts), the most important knife feature is handle design. The handle needs to effectively function as sheath and blade lock while providing an ergonomic and secure grip, and if possible some level of aestheticism (good looks sell a lot of knives). Secure grip is very important, since most folding knives do not have quillons (a handguard) to keep your hand from sliding up onto the blade when thrust-cutting.

Handle and blade features are often described in unfamiliar vocabulary. Here are some of the most important and arcane terms (per above photo, clockwise from top):

swedge: The spine of a knife blade, opposite the cutting edge, is sometimes ground into a swedge (false edge) to save weight, improve penetration, or simply for appearance.

opening hole: This is to provide a gripping surface for the thumb of the gripping hand to open the blade (i.e., one handed). This hole is found on Spydercos and some Benchmades. Otherwise, most knives use for opening a thumb stud on the side of the blade (see inset above) or a disc on top (as on the Emerson in my previous knife post). Some knives also use a flipper on the back of the handle, actuated with the index finger, which when the blade is open may form a finger guard (see right).

thumb ramp: While not all knives have it, a thumb ramp allows the user to better choke up on and control the blade for precise cutting tasks. Placing the thumb on top may also provide a more secure grip than a thumb-down choke. Thumb ramps usually have jimping.

lanyard hole
: A through-handle tube for the attachment of a lanyard (wrist cord).

finger groove: A scallop in the handle to improve grip.

choil: A finger groove cut into the blade in front of the handle. Often any forefinger groove is called a choil.

jimping: Also called friction grooves by some makers, to use a layman’s term. These are grooves cut in the lower spine of the blade, choil and/or handles to improve the user’s grip on the knife.

So, armed with this knife savvy, you can now impress your friends and spouse with learned observations like, “that Spyderco has a substantial thumb ramp with aggressive jimping, and quite a deep choil.” Don’t you feel smarter?

Next up: Tactical folder design (part 1)

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