Frame lock stronger then hidden liner lock?

Joe Talmadge has said quite succintly why the framelock is stronger than a liner lock. I didn't feel it necessary to state why I believe that a framelock is stronger. perhaps I should have said that it had been stated already.
"At least as importantly, when you're going to do something that stresses the knife, typically you squeeze the handle more tightly. With a framelock, squeezing the handle tightly will jam the lock into the blade tang more tightly -- to the point where on some framelocks, it can be hard to unlock after gripping tightly. On a liner lock, the hand never causes more positive engagement regarding the lockup. The best you can hope for is no engagement at all; at worst, the flesh of the hand interacts with the locking leaf and reduces the lockup integrity.

So, with the framelock, it's not just a matter of the hand helping to keep the lock closed, it's that the hand pushes the locking leaf into a tighter, more-secure position as more stress is put upon it.

I disagree that thickness of the locking leaf is the most important property regarding framelock vs liner lock. I agree it helps. But for me, it does not explain the difference in reliability between the two formats (i.e., even thick liner locks are less reliable than framelocks IME)."
 
I think the article says as much as we have - a lot depends on how the particular knife in question is designed, and quite separately, constructed on the shop floor.

As for framelock cutouts, again, if the design correctly flows force down the length of the locking leaf, then the cutout only receives compressive force. This will be well within the window of strength for the material. I've seen no posts on cutout failure, or liner failure either, because of inadequate material thickness at the base of the leaf. It's always about side forces unlocking the ramp engagement.

Of course, anyone with pics and a description of what it took to destroy a cutout relief is urged to post them. We'd all like to see that.
 
Personally I think all that would happen if it was just my hand holding the lock in place is that I'd get some trapped skin if the blade was forced back. In my limited experience, I find most framelock knives are too thin for me to grip properly - which reduces my ability to grip it tightly and hold the lock in place. I agree about the fixed blade thing - if you want strength, you want the blade in one piece.

As a sidepoint, this kind of discussion always gets me because in UK law (i'm english) a locking blade is considered a fixed blade (because some idiot lawyer convinced a judge so in the late 80s) and is therefore illegal to carry. But that's another thread.
 
I think Sal Glesser and Spyderco's destruction testing would disagree strongly that a liner lock format is much stronger than the lockback format (like that article says). There is a reason why the are no Very Heavy Duty rated liner locks (or frame locks) from Spyderco. While a given liner lock (like the Spyderco Military) can definately be extremely strong, I would find it hard to believe that there is a liner lock out there stronger and than the lockback on my Manix. That doesn't even count the reliability issue, which is most people's main objection to liner locks.

Mike
 
Very neat piece of reading 3G. But I think there are several issues to be considered along the lines of what STR already said:
1.) In that article, if I understand correctly, a custom made knife by a very capable maker was compared against run of the mill lockbacks. And as so many pointed out already, so much depends on how a lock is executed.
2.) I think the lockbacks of yore are not to be compared against Very Heavy Duty lockbacks as currently made by Spyderco for example. Unfortunately the article doesn't say how long the pipe was, otherwise we would be able to compare directly the results.
3.) Linerlocks and Framelock have one inherent weakness in comparison to a lockbar that you just don't get around: On a linerlock and framelock, the locking lever/bar/leaf acts in compression. On a lockback it acts in tension. Metals are much stronger in tension than in compression in an aspect ratio as used in a locking lever. You can try that for yourself. Take a piece of wire coathanger, protect your hands and press on the ends. The slightest bend in the wire will collapse the wire in no time (and framelocks and linerlock have intrinsically a bend in them). Now take the same wire and try to pull it apart or just lengthen it by an appreciable amount. Chances are, that you are not strong enough to do that. Now, just take a look at the thinnest part of a Manix lockbar and the thinnest part of the famelock/linerlock of your choice....
I am sure you can engineer around this shortcomming and I guess this is why there are both liner as well as framelocks that are plenty strong, but if you engineer both for maximum strength I have no doubt that the lockback can be made stronger.

On an unrelated note: The most pressure that I put on the lock of any knife is usually when I want to push the tip of the knife though something and the going is tough (like the gator example someone gave). And I would wager that this is how most slipjoints cause injury aswell. When doing so, I usually do not grip the handle with a deathgrip, but rather hold the handle fairly lightly and push mostly on the butt of the knife. So, I don't really find the reasoning that gripping a knife will improve its reliability very appealing. I think a lock should be able to stand on its own, whether the handle is gripped or not. I know that pushing a folding knife like this is a very dangerous practice and can spell potential desaster, because if that lock gives and the bodyweight is behind the butt, the knife will fold on your fingers before you can take countermeasure. This is why I do such a thing only with a knife who's lock I trust implicitely. Some people will say that this is fixed blade territory, but I disagree, because I think there are (well, I know there are, I have tried it) locks that will stand up to this treatment.
 
TheKnifeCollector said:
Joe Talmadge has said quite succintly why the framelock is stronger than a liner lock. I didn't feel it necessary to state why I believe that a framelock is stronger. perhaps I should have said that it had been stated already.
Click to expand...

OK this simple mean thet you have nothing to say... What are all you posts about then?

Thanks, Vassili.
 
tirod3 said:
I think the article says as much as we have - a lot depends on how the particular knife in question is designed, and quite separately, constructed on the shop floor.

As for framelock cutouts, again, if the design correctly flows force down the length of the locking leaf, then the cutout only receives compressive force. This will be well within the window of strength for the material. I've seen no posts on cutout failure, or liner failure either, because of inadequate material thickness at the base of the leaf. It's always about side forces unlocking the ramp engagement.

Of course, anyone with pics and a description of what it took to destroy a cutout relief is urged to post them. We'd all like to see that.
Click to expand...

Sal Glesser has stated that the cutout was the weak link in break-testing (ultimate lock strength, not reliability) Spyderco performed on frame-locks. Mick Strider has stated (see link I posted in an earlier post http://www.bladeforums.com/forums/showpost.php?p=4450703&postcount=57) that improper placement of the cutout could result in lock failure (reliability, not ultimate lock strength) by causing the lock to pop off of the tang's lock face. It appears, by having read those statements, and several of STR's posts, that the cutout is in fact an area of concern in a frame-lock or liner-lock.

Regards,
3G
 
nozh2002 said:
OK this simple mean thet you have nothing to say... What are all you posts about then?

Thanks, Vassili.
Click to expand...

Some people just enjoy voicing their opinion I guess, even if they can't explain why they formed that opinion.

Regards,
3G
 
3G, I agree that reliability and the placement of the cutout are linked. I'm just saying that the cutout is designed to have enough strength in compression to not fracture and give way.

Tension is higher than compression strength, and lockbacks do employ it well. They don't need the cross sectional area a frame/liner needs to accomplish equal holding power. Lockbacks aren't real good one hand closers, either, which really is the point of discussion in Walkers criteria - one hand use.

Of course, improper heat treatment of the lockback bar is an equally bad product of value engineering, and I've seen lockbars broken in a lot of $2 flea market grab boxes. So now we're back to junk is junk, and good is good.

Lockbars have about 50 years of manufacturing experience, now. Like the M16, once the kinks are out of the frame/liner lock design package, it will be a preferred choice. (And I "grew up" on the HK91, so that's saying a lot.)
 
I have seen no link whatsoever to what side the cut out is on as to how it directs the energy, or anything else. If you ask me it doesn't seem to matter. Whatever turns you on I guess. I've noticed Ken Onion does both and so do other makers. Chris Reeve does them inside as I do because I think it looks better personally but in testing I see no indicators that the cut out is responsible for anything other than making it easier to bend thick stock to spring the lock. When a lock slides it seems to me to be more related to the contact angle, and other geometry factors in the interface and how its relationship is in the system as a whole.

I am certain 100% that Sal would concurr with my findings but I think anyone that tests them can see its not really doing anything different to make the lock move one way or the other because in testing you see locks with the relief cut on the outside fail by slipping off as well as slide in tighter and you see that with the relief cuts made on the inside. The truth is that most liner and frame lock defeats are actually because the lock slides off the blade long before the maximum pressures are reached to really put the lock or the relief to a folding over stress level. So what that means is that if it takes 130pounds of downward pressure on the tail end or lanyard end of the folder to make the lock fold that in all likelihood it will slide off the blade before that is reached.

I don't know if you guys are aware that Cliff Stamp no longer even wastes time testing integral locks because they are so inherently unreliable that the outcome is predictable. Yes I asked him. I'm sure its also because of the ill feelings it causes when a maker or manufacturer gets told their lock defeated at x amount of force or during this or that grip or cut. Not because this really bothers Cliff but I'm sure its just not worth the hassles and just easier to refuse to do anything else with them.


STR
 
I'm not sure if Cliff is the final authority on knife locks, but it does show how much someone has been disillusioned about claims integral locks are reliable. Can't blame him.

There may be some advantage to have the cutout on a particular side to shift the pivot point of the leaf toward a position to stay locked. It's probably minimal, though, as it's fractions of an inch. Lock ramp angle probably does has more effect.

Frame/liner locks are a very simple solution at first glance, but like everything else, the devil is in the details.
 
Thank you both for your input. Going back to another part of Vassili's question; do either of you feel that nesting a liner-lock gives it an advantage in strength over a non-nested liner-lock? I must admit, my BladeTech Pro Hunter is one of the best liner-locking knives I've ever owned, and it has a nested liner-lock. This thing locks up perfectly, and it doesn't appear to have worn at all (as opposed to other liner-locks I've used for the same amount of time). The only knife I would even compare the BladeTech's lock up to is the Spyderco Military, which also has a nested liner-lock. What are you guys' experiences with nested liner-locks?

Regards,
3G
 
I'm not sure if Cliff is the final authority on knife locks, but it does show how much someone has been disillusioned about claims integral locks are reliable. Can't blame him.
Click to expand...

Well, I don't know if I'd suggest that Cliff is disillusionded about claims of unreliability so much as being disillusioned by results seen in testing proving it which would be more accurately described as factual reproduceable evidence.

Evidence I might add that was seen by Joe and Steve in their tests before Cliff tested them the same way to see the results for himself. As I recall Cliff found out about their test results and kept an open mind until he was convinced there was nothing more to learn from them.

STR
 
3Guardsmen said:
Thank you both for your input. Going back to another part of Vassili's question; do either of you feel that nesting a liner-lock gives it an advantage in strength over a non-nested liner-lock? I must admit, my BladeTech Pro Hunter is one of the best liner-locking knives I've ever owned, and it has a nested liner-lock. This thing locks up perfectly, and it doesn't appear to have worn at all (as opposed to other liner-locks I've used for the same amount of time). The only knife I would even compare the BladeTech's lock up to is the Spyderco Military, which also has a nested liner-lock. What are you guys' experiences with nested liner-locks?

Regards,
3G
Click to expand...


I must admit that Joe and I did not start out well at all due to my initial reaction that his claims of unreliability in liner locks were nothing less than someone that just didn't like that style of lock and not so much someone making statements based on reproduceable testing. Once I did the testing myself much as Cliff did it was very easily seen that the results they were seeing were in fact correct.

I still buy and use these style locks on occasion but I must admit that Joe and Steve's findings, and Cliff's not only opened my eyes to a fault in the design I had not seen before but that it changed the way I make my own as well. I am also a bit more aware when I use one of them to pay attention to them more than I used to.

Learning from testing them also prompted me to learn the other things I did about the way they are made and why, and then take things just a bit further at least in my own mind, as to how controversial they are not just in the test results but in the ways they are built and the various different opinions about the correct or proper ways to do them from the mechanical engineering point. Even the experts can't pick a way that is best but simply try to do their own to make themselves stand out from their competitor. It doesn't appear to me that making them nested, or the contact concave, or sharp angled vs more flat or anything else that makers and manufacturers come up with in various designs has much effect on the faults pointed out by twisting torque from simple wrist flex during use.

Some of the differences in how they are built may help in other ways. I mean doing a contact one way vs another may help to make it stand up better to sudden sharp contacts such as spine whacks but when it comes to the sideways forces of the torque test they all can be faulted. Perhaps other users will disagree.

To me the build of the body and the overall ridgidity of it can be more of a factor in making the lock more stable than anything else like the way the contact is made or any of the other little tricks done to make them better. But then just when you think that being more rigid is the key you find one like the Rat Trap that has a lot of flex in it, is a long folder with lots of leverage but still has what turned out to be a very reliable lock. Go figure.

STR
 
I'd like Sal's nested lock a lot better if it didn't pinch the meat of my index with some models. I do feel its a lot better strength wise and even reliability wise as well but the blades do wear the locks and develop some play in them vertically on occasion. I don't think they are quite as prone to this as liner and frame locks are though.

STR
 
alejandrino said:
. I think failures could also be due to human ineptitude !!
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I agree with this. From the sound of this thread there are a lot of people trying to survive in a post apocalyptic world with a single folding knife. I try not to ruin my knives. I love all my knives or I get rid of them. There is nothing more dangerous then a poor tool. I've carried and used a knife daily for 35 years. I can not remember a single knife folding back on me, including my cub scout knife that had no lock and was not stainless. I mention the stainless because I was reading Tactical Knife mag about a fixed blade maker working in 01 steel. It is not stainless, and he was asked why he used it. He replied that it is great steel for edged tools and that if some one didn't know how to take care of a knife, perhaps they shouldn't own one.
If I buy good tools and take good care of them, they will take good care of me.
 
aafanatic said:
From the sound of this thread there are a lot of people trying to survive in a post apocalyptic world with a single folding knife.
Click to expand...

I am not sure where you actually read this, but this thread is simple about what pro and cons each of this solution has and what is true or false in common and widely used statement that "frame-lock is stronger".

I found this discussion quite intelligent and useful and learn new points of view and information.

Thanks, Vassili.
 
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