TI framelocks, what makes for a perfect durable lockup?

[ribeyemediumrare]

Will a regular titanium framelock with a well designed lock geometry maintain the same lockup percentage and last forever after its initial seating and break in?

What cases one ti lock to have much more lock stick then another, and why do some start with lock stick but its gone after the break in? Does a small amount stick provide a lock up reliability advantage over a carburized framelock or with a steel insert where there is no stick?

What exactly causes the lock to wear quickly on some knives, is it the angle of the blade tang? Is it how hard it is used or how often it is flicked open?

I noticed the finish of the tang on some knives can be very rough, Is it possible this is what is sanding down the titanium each time it is opened/closed? I don't see how using a knife very hard would affect the lockup other then allowing it get pushed slightly further. When you close the knife if you push the lockbar fully out of the way of the tang and then close the blade I dont feel any rubbing against the two but if I start applying closing pressure on the blade while I open the lockbar the two grind against each other. I would think that maybe having a rough tang finish combined with closing ithe knife in the second way I described could what causes the lock to wear. I don't see how flicking a knife open vs rooling it open would accelerate lock wear since the speed and force of deployment does not make hte lockbar close in with any more force.

What is the proper and wrong lock geometry that someone should look for in evaluating a framelock? A knife that ive heard of constatnly wearing down and getting lock rock was the older generation striders with the round ramp tang cut, which was replaced with a straight line tang angle, what caused the issues on those knives? Ive also heard the Dpx hest to have the same issue. Ive often heard someone says their Chris Reeve lockup hasn't moved since they've had it, is this because of the heat treat they use or is it something else?

Such a simple design seems to be a complicated thing to get right

 

[not2sharp]

A frame lock is a liner lock with an integral locking bar on the handle scale. One of the challenges is that titanium handle material is softer than the blade steel and can wear at the point where the locking bar contact the blade. For longevity most makers are now using steel inserts attached to the locking bar which protect the titanium from wear and minimizes lock stick. The resulting action is smooth and durable, but may also be more susceptible to failing a spine wack. I suspect that many of the issues reported are over blown and result from wear or insufficient break-in; as well as, the over-hyped expectations set by the makers . The lock design is fine and usually strong; but it is still a folding knife, so some care needs to be taken in use and you shouldn't be pounding on the spine as you would a fixed blade.

n2s

 

[RBid]

A frame lock is a liner lock with an integral locking bar on the handle scale. One of the challenges is that titanium handle material is softer than the blade steel and can wear at the point where the locking bar contact the blade. For longevity most makers are now using steel inserts attached to the locking bar which protect the titanium from wear and minimizes lock stick. The resulting action is smooth and durable, but may also be more susceptible to failing a spine wack. I suspect that many of the issues reported are over blown and result from wear or insufficient break-in; as well as, the over-hyped exceptions set by the makers . The lock design is fine and usually strong; but it is still a folding knife, so some care needs to be taken in use and you shouldn't be pounding on the spine as you would a fixed blade.

n2s

If a steel insert is a cause for spine whack failure, then it follows that steel liner locks, or carbeurized ti lock faces, must also be susceptible.

It would also follow that we’d be hearing reports of lock failure from all brands using those. Reate, Olamic, Koenig, WE, Kizer, etc, would all be exhibiting whack slips.

 

[ribeyemediumrare]

A frame lock is a liner lock with an integral locking bar on the handle scale. One of the challenges is that titanium handle material is softer than the blade steel and can wear at the point where the locking bar contact the blade. For longevity most makers are now using steel inserts attached to the locking bar which protect the titanium from wear and minimizes lock stick. The resulting action is smooth and durable, but may also be more susceptible to failing a spine wack. I suspect that many of the issues reported are over blown and result from wear or insufficient break-in; as well as, the over-hyped expectations set by the makers . The lock design is fine and usually strong; but it is still a folding knife, so some care needs to be taken in use and you shouldn't be pounding on the spine as you would a fixed blade.

n2s

Yes I understand that ti is softer then steel which makes it prone to wear, but that does not answer what causes the wear. Some steel linerlocks also wear very quickly and some ti framelocks seem to not wear at all compared to other ti framelocks. This makes me suspect the issue isn't the soft titanium but something else like the angle of the blade tang where the lock engages and the amount of friction. I wouldn't say most makers are using the steel inserts, if you look at the number of high end production and custom knives made that are titanium frame locks steel inserts are not used much.

 

[kuraki]

The seemingly simple mechanism has a lot of variables playing into the questions you're asking.

What is the surface finish of the lock face on the blade? The surface finish on the lock face of the frame?
What is the angle of the lock face on the blade?
How much engagement between the two lock faces? How much contact surface when locked?
How much spring pressure in the lock?
What alloy is the frame? What condition is the alloy in?

And while you're correct that flipping open doesn't cause the lock bar to actuate with more force, the conclusion that it therefore does not create more wear IMO is incorrect. Flipping, at least especially hard, will often result in the lock bar engaging further into the lock face of the blade, not because it sprang with more force, but because the blade opened against the stop pin slightly further than it would when opened slowly. This results in greater compression between the lock bar and lock face, which will mean increased wear when the lock bar is disengaged. How much wear, if even a discernible amount, depends on the other variables as well.

 

[not2sharp]

This may be helpful.

n2s

 

[ribeyemediumrare]

The seemingly simple mechanism has a lot of variables playing into the questions you're asking.

What is the surface finish of the lock face on the blade? The surface finish on the lock face of the frame?
What is the angle of the lock face on the blade?
How much engagement between the two lock faces? How much contact surface when locked?
How much spring pressure in the lock?
What alloy is the frame? What condition is the alloy in?

And while you're correct that flipping open doesn't cause the lock bar to actuate with more force, the conclusion that it therefore does not create more wear IMO is incorrect. Flipping, at least especially hard, will often result in the lock bar engaging further into the lock face of the blade, not because it sprang with more force, but because the blade opened against the stop pin slightly further than it would when opened slowly. This results in greater compression between the lock bar and lock face, which will mean increased wear when the lock bar is disengaged. How much wear, if even a discernible amount, depends on the other variables as well.

Can you please explain which of these things would lead to more wear. What goes into consideration when choosing the angle of the lock face on the blade, whats the proper angle and engagement you would want to see for a durable lock? I would guess that a strong spring pressure and a rough surface finish on the blade face would cause more wear, why wouldn't makers slightly polish that part of the blade ?

 

[ribeyemediumrare]

This may be helpful.

n2s

.....I hope this a joke? I obviously know what a framelock is if you read my question.

 

[not2sharp]

.....I hope this a joke? I obviously know what a framelock is if you read my question.

You may know what a frame lock is, but have you considered the geometry of the mechanism? Look at the drawing and consider how forces are transferred between the parts, and you will be able to answer some of your own questions.

n2s

 

[evilgreg]

FWIW, all of my knives that fail a spine whack have steel inserts on their lock bars.

I tested about three dozen knives the one day, after the ZT thread heated up. It wasn't that every knife with an insert failed--that wasn't the case; what did surprise me, though, was that every knife that failed had an insert.

 

[kuraki]

Can you please explain which of these things would lead to more wear. What goes into consideration when choosing the angle of the lock face on the blade, whats the proper angle and engagement you would want to see for a durable lock? I would guess that a strong spring pressure and a rough surface finish on the blade face would cause more wear, why wouldn't makers slightly polish that part of the blade ?

I can give you my opinions.

The angle and surface finish of the lock face is a balancing act between positive lockup and easy release (no sticking.) My opinion is that most production knives I've seen have too steep of an angle on the blade lock face. The steeper angle allows a little greater variation in tolerance of parts to still "work" as intended, as well as limiting stick over a greater variation of surface finishes. The shallower the angle, the stronger the lock and the greater the surface contact between the blade and lock bar, however too shallow leads to taper lock sticking, requires a little more care in surface finish to prevent sticking, and allows for less variation in lock bar geometry between disengaged and going passed ideal engagement.

It's very hard for me to say "This is the ideal set of variables to prevent wear" because they may result in a wear proof lockup that is easily overcome by mechanical advantage against the lock, and hardly being worth called a lock. The ideal set of variables for ultimate lock strength may be miserable to unlock and wear prematurely. It's a balancing act, like many engineering problems.

In general, I've found that a 6AL-4V titanium lock bar and a 220 finish, spring tension just sufficient to provide acceptable detent, a blade lock face ground to 8 degrees with a 220 grit finish, and interacting lock geometry between the two that amounts to a single contact pad about .020-.030" in diameter (roughly guessing I have no way to measure this) that is at the maximum distance allowable by the design 90 degrees from the pivot point, provides an ideal lock that once broken in (getting the high points in the surface finish of the Ti to "lay down" essentially) will pass any reasonable lock test such as a light spine wack, it will unlock without sticking, and it will not wear prematurely.

YMMV.

I think the biggest issue with wear is the frame alloy and the surface finishes. The hard steel blade with too rough of a finish can certainly act like a file in regard to the lock bar. 6AL-4V doesn't wear as easily as some other grades of Ti. The 220 grit finish I call out above seems to be the sweet spot between rough-file like activity and too smooth sticking. And once that little contact pad is established, it does not seem to grow much over time with use.

Why any particular maker does or doesn't do something in particular is impossible for me to say, but I would generally guess it's relative to gaining the highest process stability while minimizing costs, and providing what they consider acceptable performance.

 

[falar]

FWIW, all of my knives that fail a spine whack have steel inserts on their lock bars.

I tested about three dozen knives the one day, after the ZT thread heated up. It wasn't that every knife with an insert failed--that wasn't the case; what did surprise me, though, was that every knife that failed had an insert.

That argument is completely useless too. What possible reason would someone grasp a framelock knife in a manner that doesn't squeeze inwards and whack it on the spine? What purpose could be served by using a knife in this manner?

If for some reason I had to use my knife to stab someone with a framelock I'm going to have a hell of a grip on the knife's handle which means that lockbar isn't popping out. I have seen that "spine whack" argument heat up so many times and all for nothing.

That's another reason why I've moved away from liner locks. They don't afford that same security.

 

[not2sharp]

That argument is completely useless too. What possible reason would someone grasp a framelock knife in a manner that doesn't squeeze inwards and whack it on the spine? What purpose could be served by using a knife in this manner?

If for some reason I had to use my knife to stab someone with a framelock I'm going to have a hell of a grip on the knife's handle which means that lockbar isn't popping out. I have seen that "spine whack" argument heat up so many times and all for nothing.

That's another reason why I've moved away from liner locks. They don't afford that same security.

I have never been particularly concerned about the spine whack test.

The modern locking folding knife originally evolved to provide a safer folding hunting knife. Hunters were getting a little self conscious about walking around in town with a sheathed fixed blade on their belt and traditional slip joints could be dangerous when out of sight, as in when working with your hands inside an animal carcass. For me the frame lock is ideal for this because it is the only mechanism that allows you a degree of mechanical feedback. We have many good locking systems, but any of them can be defeated by gunk in the locking mechanism or by being inadvertently knocked and released during use, and there isn't much that you can do with most of these locks. At least with the frame lock you can apply pressure or caution if the lockbar moves as you are working with it.

n2s

 

[Dangerously]

You may know what a frame lock is, but have you considered the geometry of the mechanism? Look at the drawing and consider how forces are transferred between the parts, and you will be able to answer some of your own questions.

n2s

Well, to be fair, that picture does not actually show the tang geometry of any actual frame lock knife I’ve ever seen.

 

[evilgreg]

That argument is completely useless too. What possible reason would someone grasp a framelock knife in a manner that doesn't squeeze inwards and whack it on the spine? What purpose could be served by using a knife in this manner?

If for some reason I had to use my knife to stab someone with a framelock I'm going to have a hell of a grip on the knife's handle which means that lockbar isn't popping out. I have seen that "spine whack" argument heat up so many times and all for nothing.

That's another reason why I've moved away from liner locks. They don't afford that same security.

I wasn't making any sort of argument that I'm aware of, just making an observation. In this particular mode of failure my titanium lock bar knives did significantly better than my knives with steel inserts.

Another observation: as an experiment, I intentionally flipped open the same Spyderco Southard a ton for a year. I forget what I was doing, something like 20 - 25 flips a day. I could dig back to my old posts and find it. In any case, after flipping it many, many thousands of times that year, the lockup position was unchanged (or close enough to unchanged to not be visible to the naked eye when comparing before and after photos). Which is not to say that wear does not occur--of course it must be happening--but rather to suggest that, at least for a well-constructed knife, wear that causes issues may take a long time.

 

[ribeyemediumrare]

I can give you my opinions.

The angle and surface finish of the lock face is a balancing act between positive lockup and easy release (no sticking.) My opinion is that most production knives I've seen have too steep of an angle on the blade lock face. The steeper angle allows a little greater variation in tolerance of parts to still "work" as intended, as well as limiting stick over a greater variation of surface finishes. The shallower the angle, the stronger the lock and the greater the surface contact between the blade and lock bar, however too shallow leads to taper lock sticking, requires a little more care in surface finish to prevent sticking, and allows for less variation in lock bar geometry between disengaged and going passed ideal engagement.

It's very hard for me to say "This is the ideal set of variables to prevent wear" because they may result in a wear proof lockup that is easily overcome by mechanical advantage against the lock, and hardly being worth called a lock. The ideal set of variables for ultimate lock strength may be miserable to unlock and wear prematurely. It's a balancing act, like many engineering problems.

In general, I've found that a 6AL-4V titanium lock bar and a 220 finish, spring tension just sufficient to provide acceptable detent, a blade lock face ground to 8 degrees with a 220 grit finish, and interacting lock geometry between the two that amounts to a single contact pad about .020-.030" in diameter (roughly guessing I have no way to measure this) that is at the maximum distance allowable by the design 90 degrees from the pivot point, provides an ideal lock that once broken in (getting the high points in the surface finish of the Ti to "lay down" essentially) will pass any reasonable lock test such as a light spine wack, it will unlock without sticking, and it will not wear prematurely.

YMMV.

I think the biggest issue with wear is the frame alloy and the surface finishes. The hard steel blade with too rough of a finish can certainly act like a file in regard to the lock bar. 6AL-4V doesn't wear as easily as some other grades of Ti. The 220 grit finish I call out above seems to be the sweet spot between rough-file like activity and too smooth sticking. And once that little contact pad is established, it does not seem to grow much over time with use.

Why any particular maker does or doesn't do something in particular is impossible for me to say, but I would generally guess it's relative to gaining the highest process stability while minimizing costs, and providing what they consider acceptable performance.

Thats makes perfect sense. Thats about as good of an explanation iI could have hoped for! One more thing I'd like to know is what is your opinion of carburized titanium lock faces and what effect would the treated surface have in this balancing act of lock design. It is such quick and easy process and should help with stick and wear, why are't production/custom makers taking the extra 2 minutes to do this? I would guess that maybe it hinders the lock from breaking in and the high point laying down to a flat spot properly. Or maybe it would cause the lock to be less secure with the steep angles you described. unless there is something else I'm missing

 

[shinyedges]

I wasn't making any sort of argument that I'm aware of, just making an observation. In this particular mode of failure my titanium lock bar knives did significantly better than my knives with steel inserts.

Another observation: ss an experiment, I intentionally flipped open the same Spyderco Southard a ton for a year. I forget what I was doing, something like 20 - 25 flips a day. I could dig back to my old posts and find it. In any case, after flipping it many, many thousands of times that year, the lockup position was unchanged (or close enough to unchanged to not be visible to the naked eye when comparing before and after photos). Which is not to say that wear does not occur--of course it must be happening--but rather to suggest that, at least for a well-constructed knife, wear that causes issues may take a long time.

I think galling is the reason insertless framelocks do better.

 

[kuraki]

Thats makes perfect sense. Thats about as good of an explanation iI could have hoped for! One more thing I'd like to know is what is your opinion of carburized titanium lock faces and what effect would the treated surface have in this balancing act of lock design. It is such quick and easy process and should help with stick and wear, why are't production/custom makers taking the extra 2 minutes to do this? I would guess that maybe it hinders the lock from breaking in and the high point laying down to a flat spot properly. Or maybe it would cause the lock to be less secure with the steep angles you described. unless there is something else I'm missing

I haven't worked with it enough to really form an opinion. Offhand I'd wager you're simply trading lock bar wear for blade lock face wear. I've only done it on one knife myself, and while it's easy to apply, it's harder to control the surface finish.

There are some makers I respect and admire greatly who do it as well as some I have equal respect and admiration for who do not.

 

[marrenmiller]

I think there's a lot of poorly executed frame locks on the market made by companies that have forgotten or never understood how lock engagement is a subtle geometric relationship which depends on the materials being mated together.

If they get the geometry right, that's most of the battle right there.

 

[shinyedges]

I think there's a lot of poorly executed frame locks on the market made by companies that have forgotten or never understood how lock engagement is a subtle geometric relationship which depends on the materials being mated together.

If they get the geometry right, that's most of the battle right there.

You should call them up and offer your services, you'd be doing us all a favor. What is the proper geometry on the tang and lock bar?