Frame-Lock: History and Features
One of the most popular modern knife locks is the framelock, an improved version of the classic "line lock". It is highly durable, easy to open with one hand, and can also be made of a variety of materials.
Frame-lock or as this lock was originally called, integral-lock, was created in the late 80's by South African knife designer Chris Reeve. The main goal of the designer was to maximize the strength of the liner lock, which had already gained popularity at that time. The main problem with its operation was not high reliability under side loads. Usually, when a blade was subjected to high lateral load, such as when working on wood, the liner moved, which led to its quick wearing out and failure. The design of knives with a liner-lock always included a padding on the handle, so the lock could not be made with a large thickness of metal and, accordingly, the strength of the construction could not be increased. In order to overcome the problem, it was decided to get rid of the padding, which made it possible to produce a lock of almost any thickness. Chris Reeve compared the strength of the frame-lock, with a "bank vault" lock. However, such a design initially had a significant disadvantage. Liner locks were made of steel, and the reinforced steel lock significantly increased the weight of the knife. The master decided to use a titanium plate as a side panel for the handle with a lock instead of a steel plate. Thus, in 1990 the first full-fledged and functional frame-lock was introduced on the legendary Sebenza knife. The new product was warmly welcomed by the knife community around the world, becoming one of the best knives of its time.
The new lock was strong, lightweight, and could be easily opened with one hand. It was designed as a notch on one of the panel of the metal handle, in which an internal spring tension was created. When opening the knife, when the blade is completely out of the handle, the locking plate of the lock springs inward and rests on the heel of the blade, fixing it in the open position. The subsequent closing of the knife was easy to do with one hand, and it could be done without looking at the knife, which certainly increased the convenience of use of the knife. In order to prevent the blade from freely falling out of the handle when the knife was closed, a locking metal ball ("detent ball") was placed on the top of the lock. It entered the groove in the heel of the blade and kept the blade closed, and at the same time provided tension for quick opening of the blade. In addition, such knives usually had a stop pin that determined the end position of the blade in the open position, which also helped to reduce wear of the locking mechanism.
Despite the mass of positive qualities, the subsequent operation of the frame-lock revealed a number of shortcomings, to correct which the lock has received a whole set of additional elements.
One of the first additions to the lock was the so called "steel lockbar insert" - a small rectangular plate made of hardened steel, with hardness no less than that of the blade. It is screwed to the upper part of the frame-lock, at the place of contact with the tang of the blade. When opening the knife, it is the spacer that is exposed to abrasion and wear, while the main lock spring is not damaged. The use of such a solution was caused by the rapid wear of the soft titanium surface when rubbing against hard steel, the heat treatment of which often exceeded 60 HRC. Also, when using a titanium frame-lock jamming was detected, when the plate was rigidly locked in the open position and jammed, and did not allow quick closing of the knife. Also, the use of the spacer allowed using not only titanium, but also soft steel and aluminum as the material for the frame-lock. An important advantage of this invention was the easy replacement of spacers when they wore out, allowing the life of the knife to be prolonged for many years.
Another addition to the frame-lock was the overtravel stop, placed on the handle panel directly next to the lock plate. This was developed by Rick Hinderer to prevent the spring from overtraveling during rapid opening. It is a fairly simple yet effective device, consisting of a round metal washer and a locking screw. In recent years, a number of knife manufacturers began to use the spacer surface for the same purpose, which is located on the spring of the lock with a slight offset and hooks the main plate of the handle with its edge when the knife is opened.
An improved version of the locking washer was the special Rotoblock lock proposed by Italian designer Michel Molletta. In addition to the locking washer, it includes an additional locking device with a rotating round insert and firmly fixes the lock when the blade is open. The strength of the Rotoblock lock is often compared to that of a fixed-blade knife.
In the early 10's of the XXI century, the standard frame lock received an alternative in the form of a modification - the subframe lock. The design of this lock requires that the steel spring is not part of the plate cut into it, but is fastened with screws from the inside. The lock is well realized on handles made of soft metals: titanium, aluminum and even carbon plastic (carbon). It is just a little less strong than a standard frame-lock, but has a memorable appearance and fits into a variety of designs.
The frame-lock is currently one of the most sought-after by manufacturers around the world. Relative ease of manufacture, reliability and ease of use have given it a well-deserved reputation and stable consumer demand.