Slip-joint construction with lock to prevent accidental closing properties:
One of the advantages with the Swiss
construction is the precision of the spring. The forces working on the joint between the tang and back of the blade vs. the spring can be formidable. During force-cuts the precision of the blade and spring must
be 100%. The dimensions on the spring must follow the cutting tasks intended. It is the precision and material tolerances between the blade and spring that prevents collapse. This spring must also be the guide for the opening and closing of the blade.
Victorinox made an impregnable spring that will be able to open and close an extreme number of times. It is designed perfectly with contact points towards the blade. The locking mechanism
is the backup of the design and construction. It will take much more compared to the slide-lock design. The dimensions of the rivets, spring and contact areas at the blade tang must have precision and correct design. There are more factors as well and that
is during force the spring must not be pushed backward in a way that compress the steel. This will destroy the functionality of the knife. The spring may therefore have a center rivet that prevents the spring being pushed back. The spring must be designed
to take the forces working there too. On the fireman there is also a second center rivet that is open to see. There is a design on the spring that rest against it and at the same time next to it another design that act as a stop for the blade in rest closed
Wenger and Victorinox has really understood the spring!
The precision on the slip-joint spring is by
far the most important for this large blade and the little play against the lock may be unavoidable. It is designed so and as said it is only there as a backup.
Last today i would like to talk some more on the flexibility and elastic region of the spring. The spring is impregnable and it must be able to handle all the factors mentioned above. There is flexibility
in the spring when you open and close the blade. There is also some flexibility when the blade is fully engaged. There is what I believe is the elastic region of the complete spring and design as well.
Stay strong and keep your edges sharper! A SAK need some maintenace from time to time and if you keep the edge sharp at all times you will preserve longer lifetime on it.