RJ Martin a écrit:Consider the lock to be acting as a column supported where the lock bar cutout starts. Ideally, the lockbar would be directly behind the blade, and precisely in-line with the centerline of the blade. Then, the load on the column (lock bar) would be purely vertical. Of course, this is impossible, as the column (lock) needs to be off-center so that there is room for the blade to close. But, putting the lock cut-out on the outside means that the lock-bar needs to bend at a smaller angle in order to engage the tang of the knife. Thus, the column is more nearly vertically oriented. More vertical=harder to push off-center, which is one way that locks fail.
If you make an analogy to cutting down two trees, one that stands perfectly vertical, and one that leans, you will see what I am saying. For the vertical tree, you will have to progress pretty far with the felling cut, and possible need to push (or pull) the tree to get it to fall. The leaning tree will fall much easier, because gravity is helping you and the tree is already unstable.
Fun stuff to think about.………..
Now, this is a small point-You can certainly make strong, reliable locks in either configuration (I have made them both ways), but, putting the cut on the outside definitely keeps the line of force on the lock more in-line with the blade/centerline of the knife. How the geometry of the tang interfaces with the end of the lock bar can have a much more significant impact on lock failure than which side of the lock is relieved.
As to the points about leaving enough material for strength vs. having a lock that is too stiff to manipulate, that can be balanced by choosing the right width for the lock bar. For two locks, relieved to the same thickness, a narrower lock will release more easily than a taller(wider) lock.
extrait d'ici http://www.bladeforums.com/forums/showt … k-cut-outs