Advice need on what angle to put on the frame lock

[alan0354]

Hi
Here you go

Kyley Harris "cKc" https://www.youtube.com/@knivesandstuff

if you imagine taking a normal slanted framelock, but place a "wall" at the end so that it cannot go further, or bind up.. then concave out the centre of the lockface, and convex the lockbar so that under force it cannot slide off. All energy pushes the lock inwards to the centre.

The design is, rather than preventing lock rock, to guarantee that it will never bind up and jam, and never come off the lock (unless destructive force is applied).

Thank you, that's how I would expect, to have a discussion. We just present our opinions and talk. I never insist I am right, just present my opinion like in my very first post and let people to either agree or disagree, and present their opinion like you are doing. That's how a discussion should be.

I read what you said a few times, this is the drawings from what I understand from you and see whether I got your idea correct:


Fig. a shows what I understand from you. The bottom of the blade is CONCAVE and slanted towards the Wall on the right side. The liner top is CONVEX shape(GREEN). The WALL is on the right side to prevent the liner from going towards the right too far.

I issue is show in Fig. (b) and (c). If you concave the bottom of the blade. In order for the liner to go UNDER the blade, it has to pass through the left side of the CONCAVE as shown in (b). BUT if you make the liner short enough to pass under the left side of the CONCAVE. When the liner stop in the middle of the CONCAVE, it will be way too short and not touching the bottom of the blade!!! The blade is not going to be locked tight and rattle. There is not way you can have the liner long enough to be tight in the middle, but still can pass the edge of the bottom of the blade on the left side.

Maybe I miss understand your description. Maybe it would help if you draw it out.

I went through a few of the videos you posted, I have not found anything that is relevant to the discussion. Maybe you can link the specific video on this subject.

Thanks

 

[alan0354]

In my opinion, absolute lock strength is WAY overrated. Why? Because as a rule, when you're applying maximum force to a knife it isn't the lock that's preventing failure -- it's the stop pin(s) or blade stops. The lock prevents the blade from closing when pressure is applied to the spine. In ordinary use ... not a lot of pressure is being applied to the spine. I guess the main exception would be when you get the blade stuck in something, but even then ... you're going to rock it out rather than trying to muscle it straight out.

It is true that the lock really doesn't have to be super strong as it only encounter human strength. But it's not that hard to make it strong and it's always nice to over kill than not.

Actually in post #109 in the last page, I addressed this very thing and try to look into what design is the best, BUT then I think about it like you said, people are NOT going to apply a lot of force to warrant that much attention. It's kind of SILLY, so I just let that go and moved on.

From what I read, hitting the spine on concrete is about the most severe way of testing the line lock. I am surprised it won't scratch the spine of the knives on all my knives I tested.

 

[alan0354]

http://www.cliffstamp.com/knives/reviews/faq/lock.tests.html Liner lock FAQ by Joe Talmadge

The last part of this article is something I experienced:

Joe Talmadge's tests:

• Open knife, then thumb the lock aside (blade is still open). Wiggle the knife back and forth. If the blade has *any* play at all, that's a bad sign. It might just be that the pivot is too loose, so tighten the pivot until there is no more side-to-side play, and then make sure the action is still acceptable. Sometimes a knifemaker will have a bad action, and then make it appear smoother by loosening the pivot too much.
• On top of that, I do the "white knuckle" test, which many makers also fail. Making believe I'm under stress, I grab the knife in a very firm grip, letting the flesh of my fingers sink in and around the liner to whatever extent this happens. Now the question is: will small movements unlock the lock (if a small movement moves the lock AT ALL, assume it can unlock it)? If the lock is too loose or too high relative to the handle scales, a knife that passes the other tests might fail this. I made an expensive folder from a well-known maker fail this way. I sent it back to him and he fixed it to my satisfaction. That is why I like the AFCK-style handles that do not give easy access to the lock via a cut-out -- I'd rather it be a little harder to unlock than to unlock accidently under weird conditions.
• Bob Kaspar recommended a torque test as well, which is a test many liner locks fail. You want to open the blade and then torque it while applying pressure against the spine. The lock should not fail simply because the blade is being torqued a bit. I do this test by sticking the blade through something hard, a few layers of strong cardboard or wood, and then torquing the blade while trying to shut it.

I actually have real experience of this, NOT to the point of blade unlock, BUT the blade RATTLE.

I practice knife fight, I practice switching from regular grip where the blade pointing out from the index finger and thumb for normal swing and thrusting. I switch to knife to opposite direction where the blade pointing out from the baby finger and do hammer fist type stabbing. Sometimes when I switch to hammer fist and stab, I can feel the blade rattle on one particular knife. I really looked into this, the cause is the flesh of the finger push the liner towards the unlock direction just enough to give some slack between the bottom of the blade and the liner. Not much, but it happened.

When I release the grip, the knife completely lock up again and no rattle. This is a very valid point to look at.

Yes, the liner is a little high on this knife. I did grind it down, but occasionally, it still happened. It is by no means moving to dangerous point that the blade can unlock, but it's something to look at.