Anyone with a forged blade can use dexterity to construct an inner bearing, handle scales and a folding axle. The biggest mechanical challenge is the locking function of the unfolded blade. Metalworking machinery must always be available for a backlock knife.
Blade and handle
When building a folding knife, the only knife that can usually be considered for do-it-yourself is the backlock knife, whose internal construction, including locking technology, is the easiest to implement. Spring lock variants such as Lever or Linerlock knives require a more complex assembly, which is only possible with professional knowledge and equipment.
With the backlock, the blade locks into place after folding open at the joint by engaging a retaining hook in a blade recess. The hook is located at the end of a kind of back rocker in the handle. The lock can be released by lifting the hook. Depending on the type of construction, this can be done by pulling out or “pushing” the rocker.
Construction, components and shape of the jackknife
The basis for the construction of a folding knife is the appropriate blade. It should taper delta-shaped towards the tip of the blade, with the cutting edge increasing in angle towards the tip over about the last fifth of the blade’s length. The hinge side of the knife blade must be rounded and have a hinge hole corresponding to the symmetry. At the upper end of the blade, in the extension of the back of the blade, there must be a recess for the locking hook.
Two so-called sinkers serve as a position bed for the folded blade in the knife. They consist of two metal plates, which are attached to both sides of the hinged side of the blade at a distance equal to the thickness of the blade. The locking rocker is placed on the back of the knife opposite the blade insertion slot.
Set metal strip as rocker
Both screws with a turntable and turn rivets can be considered for the joint connection. After fastening the first board, the rocker is inserted at the top so that it pops into the recess when the blade is opened. Depending on the type of construction, the rocker must be fixed at one or two points on the blank in such a way that enough play remains to push out the locking hook.
Tips & Tricks
Before you completely build a folding knife yourself for the first time, try to purchase an old inexpensive model. Disassemble the handle scales and a circuit board and use it as a guide.