Coil Springs or Spring Steel????

[L6steel]

I hope to start making autos soon, and need to know which spring type people prefer. Most of you are familiar with a Boker Top Lock which uses a coil spring. One benefit to this set up is the spring can be replaced or removed at will. Would you folks prefer this set-up as opposed to a piano wire spring or a Y spring? Thanks for the input!!Also, what style of auto do you prefer? Michael

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"Always think of your fellow knife makers as partners in the search for the perfect blade, not as people trying to compete with you and your work!"

 

[Jeff Clark]

I usually worry more about the strength of the lock than the type of spring in an auto, so long as the spring will get it opened and locked. In order of theoretical reliability, #1 is a coil spring, #2 is a deflection spring made out of cold drawn steel (piano wire), and #3 is any old spring you can form and heat treat. The coil spring is generally under much lower stress, the piano wire has a really optimal grain structure, while the #3 choice is excellent if you make it excellent. Hey, knock yourself out.

 

[Cougar Allen]

The cool thing about a coil spring is stresses and strains are evenly distributed throughout the spring, inherently. Other spring types can serve well for many applications, and I don't see any reason why a well designed and made V spring wouldn't serve perfectly well in an auto knife and outlast the knife, provided it is specifically designed for the application to distribute the stresses and strains over a long enough portion of its length, and it is manufactured to that design with sufficiently small tolerances. With a coil spring, though, you don't have to worry about that -- and your customers don't have to worry about whether you did that right, either.

-Cougar Allen :{)