Today i will explain a few details on the slip-joint spring for the belt-cutter on the Fireman. I have noticed over the years that some ask about the raised spring. I have explained this a few times
before. The rescue blade or belt-cutter got a raised spring when the blade is in open position. I will explain a few things I know and what I have experienced from the constant quality development and evolution.
The individual springs on the SAK sandwich construction got individual abilities. Some are designed for more than one function. The springs are depending on if a blade got a locking mechanism or not. Some are designed so it can make stronger
pressure to prevent accidental closing and some springs are more solid to be able to take force against the spring mechanism. Some are also made special in design so it can function as a support for the entire construction in a more advanced way than usual.
A slip-joint spring is advanced and shall be able to be opened and closed for a lifetime of use. The tang and slip-joint springs are polished so you get precision, corrosion resistance and
functionality with durability. Depending on where the spring and function is placed in the construction and for what use it may have alterations in design and shape.
If you look on the RescueTool
belt-cutter/rescue blade then you can see a more advanced design that got a greater functionality and safety. The spring is raised still.
If you look on the more even more advanced and developed
Rescue blades/gutting blade used on the Dual Pro, Hunter XT and more then you see the development.
Depending on what category the springs will be stronger for the professional tools.
A slip-joint spring designed for having a backup lock to prevent accidental closing may be different in design. It still will have the main purpose as a spring that will fulfill every aspect of use
without the lock. The slip-joint spring may be used for more than one function.
Because of a constant quality
development you will find variations and evolution.
In the Victorinox evolution you can see how the spring and tang design vs. each other got contact areas changing and develops. To prevent
accidental closing on a traditional slip-joint spring you can make the pressure stronger or you can alter the angle in design. You can make additional additions to the tang construction to be able to function better against accidental closing. At some point
depending on the length and size of the function and for what use then the locking mechanism to prevent accidental closing must enter at some point. The design can be perfected in the contact areas with the slip-joint spring so you can have the
main philosophy of use that there is no lock at all. Still you know it is there and you get a higher confidence during use. It is unavoidable that a lock must be made at some point.
Victorinox spring is in the elastic region and this means opening and closing all functions at the same time with damaging the construction. The spring is so advanced and it is a secret to the quality.
A slip-joint spring must be strong enough to take the use it is intented for.
I love mechanisms:
Who made it first I do not know, I do know it would have to take archelogy and study the human
history to find who made it first.
Locks to prevent accidental closing have seen different applications outside just the knife blades.
These types can be made with a liner that typically will prevent the blade or function to accidental close. Many times it is not a full contact lock until a small pressure against the blade will make it fully in contact with the
locking liner. It is typically that such mechanisms are in combination with a slip-joint design. The spring will make the usual functionality and the locking liner will make sure it will not fold accidentally. This locking liner can typically contact more
than one surface on the tang of the function when engaged. It can also during stress or force against it have flexibility so it can lock further. These mechanisms may in many times have design that makes sure the contact areas will not fall outside the tang
and have a stop function on one side. It is important that the functionality to release it is sufficient comfortable. Typically the design of it must be so it will continue the ergonomics.
One must not underestimate the strength of this mechanism because the function that is most prone for activating the lock is the flat screwdriver for example. Especially during hard twisting motion this
lock will be active more often than the on a knife blade. It took some force for sure!
Locks against accidental closing are "work mechanisms" for tools and functions. It is very different
from mechanisms designed to be able to be used for stabbing. In my opinion it is the perfect example on the opposite.
Accidental close lock designs are not a full contact mechanism.
If you have a long screwdriver on a slip-joint design then you will automatically notice the need for a lock.
If you have a long screwdriver like I mentioned you will or could damage the equipment or you hand easily. If the screwdriver is shorter you will still have the need for a lock when you use force. The slip-joint spring can be made with a strong pressure that
will prevent it from sudden folding in. To be able to open it with the nail nick would not be comfortable anymore. This can cause damage to equipment and the person using it if it folds during use as well. It must therefore have a lock to this.
Typically it is so that when a slip-joint is in combination with accidental closing preventers it is actually the spring that takes the hardest load at least on the knife blade. This is because correct
use is about putting the edge against a surface and not putting pressure on the back of the blade. You use the knife as there is no lock at all. The Victorinox and Wenger slip-joint spring can take serious pressure against the slip-joint spring.
Correct knife use is about have a sharp knife all the time and therefore you prevent using too much force.