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D.O.G. Lock |
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D.O.G., which stands for Deadbolt Over Grabstep, describes the locking mechanism of this all-new folding knife. The most unique feature of this design is the lock itself. Because the deadbolt travels in a sliding motion from front to rear, the distance of positive engagement is decidedly more than that of competing designs. For example, a locking liner configuration only works when the blade tang fits tightly against the stop pin. Even a small amount of pocket lint between the stop pin and the blade tang can prevent complete opening, which in turn prevents engagement of the liner, resulting in complete failure of the lock.
This advantage of the deadbolt system can best be demonstrated by inserting a paper match stem between the blade tang and the stop pin. The match stem prevents complete opening of the blade, but the lock will still function properly. The deadbolt is propelled forward to lockup by a stainless steel coil spring completely encapsulated within a sealed chamber (see cutaway drawing). The push rod that bears against the spring has a groove cut near it’s end to retain an O-ring that fits snugly against the internal bore of the sealed chamber. This keeps dirt and dust away from the spring. Coil springs are much more reliable than flat springs and are capable of longer travel with less risk of metal fatigue. The spring loaded deadbolt also holds the blade closed under spring pressure by bearing against a lobe feature of the tang profile. A similar benefit is available in the closed position as in the open position. In this case the longer travel of the deadbolt means that the blade is spring loaded towards it’s closed position over a longer length of blade travel. The net effect is that there is less risk of unintentional opening of the blade.
The deadbolt is the key part that makes this mechanism possible. This part is machined from a solid 5/8 square bar of 440C stainless steel. The photo shows the deadbolt and the bar it’s made from. There’s more machining in this part alone than some knives. This top view of the deadbolt in an assembled folder shows how the deadbolt protrudes through both handle frames, allowing for easy manipulation with the thumb and one finger. With a little practice it becomes easy to pull the deadbolt back away from the blade tang while flipping the blade toward open. Releasing the deadbolt during the blade travel ensures that the blade will lock when it reaches open. Shock Absorbing Stop PinThe speed with which the blade can be opened led to the development of the shock absorbing blade stop. By referring back to the cross section drawing it can be seen how this innovative blade stop works. The stop pin floats freely, captured between the handle frames by an enlarged center diameter. Two grooves cut in the small diameter near the ends of the stop pin retain O-rings made of a cast urethane elastomer. The resiliency of the urethane O-rings cushions the blow of the fast traveling blade as it collides with the stop pin. Pivot PinThe pivot pin screw is not adjustable. An adjustable pivot pin is much easier to make because the adjustable feature eliminates the need for precision fitting parts, any discrepancy can be accommodated by simple adjustment. The problem with an adjustable pivot pin screw is that it cannot be completely tight and having a loose screw at a point as important as the pivot point undermines the structural integrity of the complete unit. Counter Bored Joints
Not only is the pivot pin screw torqued down tight against the bushing but the threaded insert between the handle frames is counter bored over 1/16 into the inside of the handle frames for a much stronger joint. The rear screw is constructed in the same way with the stainless steel threaded insert counter bored 1/16 into the handle frames (see drawing showing a cross section through the pivot pin). Detent PinThe only drawback to the deadbolt configuration is that once the deadbolt is pulled back away from the blade tang, the blade is free to swing without resistance. This could create a dangerous condition except for the remedy we have provided in the form of a spring-loaded detent pin that applies friction to the side of the blade tang. The detent pin slows down the otherwise freewheeling blade to a safe level. There is a partial relief cut into the side of the blade tang to clear the detent pin so that the blade will free fall approximately 20° from its closed position. This feature makes one handed closing easier. To close the blade, simply hold the knife in a position that will allow the blade to fall by gravity and pull back on the dead bolt. The blade will then fall 20° until engaging the detent. The deadbolt can then be released and the whole hand used to close the blade. Pocket Clip
Because pocket clips are considered a necessity on large folding knives like the D.O.G. Lock Folder, and because we find so many faults with current pocket clip design, we decided to try developing a better pocket clip. Typical pocket clip design is burdened from the outset with the underlying compromise of strength versus flexibility. For this reason the standard pocket clip must by necessity, be long enough and thin enough to provide the required travel at its tip. It is this underlying compromise that dictates the common practice of using a very long, very thin pocket clip made of spring steel, or other similar materials, which may be subject to breakage from sustained use.
The swing arm pocket clip resolves this dilemma by using a short stout swing arm, which is not expected to serve as a spring. The necessary spring action is supplied by the use of two urethane O-rings positioned under the screw head that connects the swing arm to the cross link, thereby providing for adjustable spring tension without compromising the strength of the swinging arm. Because the swing arm pocket clip is composed of two principle parts instead of the usual one part, and because these two parts are fastened to each other instead of the knife handle, the usual need for mounting holes in the knife handle is eliminated. Also because these two parts, the swing arm and the cross-link are symmetrical along their centerline, they can be reassembled to locate the swing arm on either side of the handle, thereby providing for ambidextrous mounting. The swing arm pocket clip has been designed to fulfill the following objectives: ambidextrous location from left to right with a single screw, complete removal without leaving an unsightly screw hole as witness to a missing part, a very short clip length so as not to interfere with the hand to handle contact, a simple means of adjusting the pocket clip tensioning to suit various carry requirements, and a more robust part being less subject to breakage. All of these requirements are met in the design of the swing arm pocket clip. |
