Pocketknife Technology 101—Inside Kershaw’s Opening Systems

Unless you’re a real knife geek, you could be forgiven for not thinking there’s any real technology in a pocketknife. It’s got a blade. The blade folds into a handle. It goes in your pocket. Pretty simple, right? But let’s take a closer look...

While that may have been true for old school pocketknives, today’s pocketknives very often have new technology engineered to make them easier than ever to use.

SpeedSafe® assisted opening knives

One common type of tech in a modern pocketknife is known as assisted opening. Assisted opening knives have a mechanism in the handle that assists the user in opening the knife, so it's ready to use quickly and easily. It also makes it easy to open the knife with one hand—very convenient when you’re steadying something in one hand while you need to cut with the other hand.

Kershaw was the first to bring assisted opening knives to a wider market—launching a revolution in opening systems. Originally designed by Hall of Fame knifemaker, Ken Onion, Kershaw’s SpeedSafe® knives flew off the shelves. Today, almost all knife companies offer some sort of assisted opening knife, but none matches the popularity or proven durability of the original.

How SpeedSafe works

Most Kershaw SpeedSafe knives open with a “flipper.” Others are equipped with a thumb stud, while still others have both a flipper and a thumb stud.

Yet the heart of SpeedSafe is its torsion bar. Closed, the torsion bar helps prevent the knife from being opened by gravity; it creates a bias toward the closed position. By applying manual pressure to the thumb stud or flipper, you can overcome the resistance of the torsion bar. This enables the torsion bar to move along a track in the handle and assist you to open the knife. Opening is smooth and the blade locks into position, ready for use.

Opening a SpeedSafe knife with a flipper

The flipper is actually part of the blade. When the knife is closed, it protrudes from the back of the handle. By pulling back on the flipper, you can overcome the resistance of the torsion bar, allowing you to open the knife. When the knife is open, the flipper moves to the bottom of the handle and often becomes part of the blade guard, which helps protect your hand from the edge of the blade. The flipper is easy for both right- and left-handed people to use.


Opening a SpeedSafe knife with a thumbstud

A thumb stud is a metal stud attached to one or both sides of the blade, near the blade’s spine. Instead of pulling back on the flipper, you push outward on the thumb stud. That outward pressure overcomes the resistance of the torsion bar, allowing you to open the knife. Most manufacturers include thumb studs on both sides of the blade so assisted opening is easy for both left- and right-handers.


Is a SpeedSafe knife a switchblade?

No. There are many unique features of SpeedSafe knives that make them quite different than knives that are considered switchblades. Unlike a switchblade, SpeedSafe blades DO NOT deploy with the push of a button in the handle or by gravity alone. Instead, the user must overcome the torsion bar's resistance to engage the assisted opening that SpeedSafe provides. Because of this, SpeedSafe knives fall fully outside the Federal definition of a switchblade. However, there may be local regulations affecting what you can own and carry. Please be responsible and know what applies in your area.

KVT ball-bearing system knives

Some people prefer a manual opening knife, but still want the convenience of one-handed opening. The KVT ball-bearing system makes manual opening as easy as assisted—without the need for a mechanical assist.

While SpeedSafe assisted opening uses a torsion bar to assist the user in opening the knife, KVT relies on a ring of "caged" ball bearings that surround the knife's pivot. ("Caged" means the ball bearings are secured within a ring that surrounds the pivot. It keeps the ball bearings in place, while allowing them to rotate freely.) When the user pulls back on the built-in flipper, the blade rotates out of the handle as the ball bearings roll in place. KVT makes one-handed opening smooth as butter. All Kershaw KVT knives open with a flipper, which provides sufficient leverage for moving the blade out of the handle quickly and easily.

In knives with the KVT ball-bearing system, you will also notice that the knife has additional "detent." This is a design feature that helps hold the blade safely in the handle when the knife is closed. When opening the knife, you'll notice a little resistance as you pull back on the flipper and before the blade moves out of the handle. That resistance is because of the detent. Having detent also helps build up pressure in the opening system so that when that pressure is released via the flipper, the blade glides easily into the fully open and locked position.

Other manual-opening knives

Kershaw also offers manual knives without KVT. With a little practice, these knives can be opened one-handed using a flipper or thumb stud, too.

Automatic knives

While SpeedSafe knives are not "switchblades," Kershaw automatic knives are. Be responsible and know the laws and regulations in your area regarding the owning and carrying of automatic knives.

That said, the opening technology inside Kershaw autos is fairly straightforward and simple. It has a coil spring (also called a helical spring) that is under constant pressure when the knife is closed. One end of the coil is in a milled out portion of the handle, the other is attached to the blade. When the button lock is released, the pressure on the coil is released, too, and the blade opens. The button lock not only keeps the blade safely inside the handle until released, but also secures the blade open during use.

Opening an automatic knife

To open a Kershaw automatic, get a good, solid grip on the knife and push the button. Because of the pressure on the coil, you will feel a definite "kick" as the coil is released and the blade comes out of the handle. (Hence the need for a solid grip.) There's no need to keep pressure on the button. Just push and release. Closing the knife is as easy as pushing the button again and folding the blade back into the handle.


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