Spring Assisted Knife vs Automatic Knives
If you live in an area that restricts the use and carry of automatic knives you may want to consider a spring assisted knife. These knives differ from automatic knives in that you use your hand to partially open the blade rather than a button or lever. Anything with a button on the handle is considered an automatic switchblade and is subject to stricter regulations. The mechanism inside the knife is what makes a spring assisted knife a spring assisted knife and not an automatic knife. Despite the difference in the mechanism, the overall deployment of a spring assist knife is very similar to that of an automatic knife.
Most spring assisted knives have a thumb stud so you can partially open the blade before the spring takes over and springs it into locked position. These knives require you to open the blade out (up to 10%) before the spring engages and fires the blade. Spring assisted knives may also have a flipper on the back of the handle that will flip the blade into place. Carrying a spring assist knife is a great choice if you live in a location that is strict on automatic knives.
There are many different variations on the mechanism that makes a spring assist knife work. But typically they will have a spring or tension bar that is designed to spring open the blade into locked position (see diagram below). What makes them different from an automatic knife is there is resistance after the blade is closed that will keep it closed until the resistance is overcome. Once the resistance is overcome – by manually pushing (ie pushing the blade open with your finger) the blade past the resistance point—the spring engages and does the rest of the work opening the knife for you. Spring assisted knives function much in the same way an automatic knife does. However due the different opening mechanism, a spring assisted knife is not subjected to the same strict laws. If you want to learn more about the spring mechanisms of spring assisted knives I highly recommend our Knife Locking Mechanisms: Spring Assisted Knives post.
The quickest and easiest spring assisted knives to open are ones featuring a flipper. This is an extra piece of steel at the back of the blade that can be used to flip the knife into place. You push the flipper past the point of resistance and the spring takes over and fires the blade into place. There are knives that open with thumb studs (a piece of stainless steel on the bottom side of the knife), the Spyderco Opening Hole (literally a hole that allows your thumb to ‘grip’ the blade to open), and flipper (explained above). You can easily get these knives to open as fast or faster than an average automatic knife.
If you’re wanting an automatic knife but live in a state where automatics are illegal, I definitely suggest to get a spring assisted knife instead. Spring assisted knives are available at Bladehq as side opening knives or out-the-front knives.
Question: I found an automatic that would not activate reliably. I removed the pushbutton from the bolster and found there is no coil-spring under the activator button. Where can I buy a tiny coil spring? Also, there doesn’t seem to be any retainer to hold the button and its tubular holder into the bolster. (It is not threaded, but there is a slot at the bottom of the button holder.) I twisted it and pulled it out with pliers. Any suggestions for re-attaching?
Is there a book or website dedicated to the repair of automatic pocketknives?
Thank you, Bryan OShaughnessy
Without knowing the specific knife I could not say exactly which spring is needed. Typically the coil spring should be just slightly larger in diameter than the pivot. As for the thing that was twisted and then pulled out, I was told you can just push it back in place… bladeforums.com is also an excellent resource for knife enthusiasts, as there are many guys who frequent the site that have been into knives for years.
Please let us know if you have any more questions! Our customer service department is also a really great resource for any questions you might have –1-888-252-3347 or questions@bladehq.com