27 April 2009

EDC Knives: Materials & Conctruction

As I mentioned in my first tactical folder post, tactical knives are usually made from high-performance steels and, for their scales (handles), "space-age" synthetic polymers. For the enthusiast, these materials may matter as much as any other aspect of design or construction. So here are some basics.

Blade Steel

Nothing about mid-to-high grade tacticals is more confusing than steel. It use to be that your choice of blade steel was carbon or stainless, the latter often stamped simply "440." Now there are a score of different wonder-steels that enthusiasts argue and obsess over, with industrial names like AUS6A, S60V, 154CM and (my favorite) 8Cr13MoV. If you just must know all about this, you can start with this knife steel FAQ (warning: a bit outdated and powerfully somnolent).

I'll make it simple. Buy a knife from a good maker and don't worry about the steel. The only crucial fact is whether it is stainless steel or not, and virtually all folding knife blades now are. This is not to say there are no real differences between all these steels. There certainly are and those differences will cost you. But to the average user no practical difference will be noticed.

And in fact, steel quality is determined as much by the tempering process as by steel type. Good makers have good tempering and much generic junk does not. I do not worry about buying mid-grade 8Cr13MoV or AUS8 knives from Spyderco or Kershaw. They know to make knife blades.


Some tactical knife handles have steel liners, to which the blade is pinned, with handle scales overlaid. Other handles are one-piece, with the blade pinned directly to them. The latter may or may not also have inlays, for enhanced grip or aesthetics. (See Knife Anatomy.)

One-piece handles are often stainless steel, as most all liners are. But handles may also be made of polymer or titanium, a very strong and light metal. Titanium handled knives are generally quite expensive.

Scales over liners are usually polymer of one of three types. The most common is fiberglass reinforced nylon (FRN), also known by the brand name Zytel. These feel like plastic but are very strong. A step up is a material called G-10, a kind of fiberglass that is very dense and grippy. G-10 has to be milled to shape, so highly-sculpted G-10 scales will only be found on more expensive production knives. Finally, more limited use is made of micarta, a phenolic resin laminate that has a very distinctive layered appearance. It can be easily shaped by hand and is therefore popular with custom and kit knife makers.

A CRKT Gallagher Rave (top) with boldly-layered micarta handles and a distinctive CRKT Tiny Tighe Breaker (bottom) featuring fluted "nylon scales with an extremely durable textured metallic coating."

Traditional wood, bone, and other natural materials are also found on some tactical knives, but they are not common. Aluminum and lower-grade plastics are also found, primarily on cheap knives, though aircraft-grade aluminum is used on some more expensive blades.

Washers, Pins and Screws

Most good tactical knives have washers, sitting in between the blade and the handle. They may be nylon, Nylotron, Teflon or phosphorous-bronze, roughly in order of quality. Why is this important? The lower friction the material, the more smoothly and easily your blade will open.

Tactical knives are held together by pins or screws, or some mixture. I prefer screws to pins. A screwed blade pivot allows you to adjust to blade tension, to fine-tune blade opening. All-screw handles can also be taken apart to clean out your knife, which is useful when it gets dirty and critical if exposed to salt water, which corrodes even most stainless steel. On the other hand, screws can come loose. As always, there are pros and cons, and preference must decide it.

Next up: Tactical Knife Makers I

No comments: