Framelock security "throw down"...

[Syncharmony]

Just to clarify. If you read my original post I described standing next to the chopping block (stump) and "throwing" the knife into it with moderate force. It probably traveled 6 inches in the air max. I'm not using it as a "throwing knife", I'm just making it stick in my chopping block without having to actually "stab" the chopping block.

If you've never done that with a knife or axe before while working with it outdoors (such as when moving back and forth between chopping/cutting tasks), then I'm shocked that you're shocked....

Genuinely curious, but is that really easier than just closing the knife and dropping it in your pocket? I mean, then you have to walk back over to the chopping block and pull it out of the block vs just reaching in your pocket and flicking it open.

It kind of seems like jumping in the car window to get into your car vs just opening door.

 

[gytheran]

...

I see toughness going down as hardness goes down in there... and some places where higher hardness comes with higher toughness in a different steel Amazing! Or not so much. Now show me data demonstrating that the force generated by throwing a hardened knife overcomes its material toughness in the manner you describe. or you can start a new thread on the topic as this isn't really part of the OP.

Nice pick and choose to try to prove your point...
A2 and D2, by those charts only has minimal benefits when made harder... not quite a selling point there...

CPM-3v
RC58 - 113J
RC60 - 95J
RC62 - 53J

A9
RC58 - 75J
RC57 - 68J
RC56 - 147J

And you notice, the steels with the higher toughness ratings are that of carbon alloyed steels, not stainless...

Material toughness is only a relative idea of how they would perform. It's academic at best and completely theoretical. You're not taking into account non-static shocks and vibrations imposed on the steel. It's not one solitary strike that will cause it to fail, but continued strikes that will erode the structural integrity of the knife. Pretty simple, really.

 

[DarkPatriot]

I've dropped my hatchets, khuk, fixed blades and folders into wood before. I kept in mind that it wasn't necessarily kosher . Still interesting. Did force make any difference?

 

[fetzer85]

Good thing I always stab people at 90 degree angles.

 

[Bigfattyt]

Yes, test your whole collection in this manner. Let us know how it works out.
Matt

This..................... Make sure you use lots of force.




What you are doing, essentially, is ruining the locking interface. Do this a few times and you can ruin the lock up forever.


For the love of all that is holy, quit it!

 

[Poez]

I am a physicist: well, I rather was a physicist. I have graduated an university a bit more than 20 years ago and did not use my knowledge for anything much ever since. But I guess that does not matter for the calculation in question is pretty simple:
So let's assume that
the blade length is around 0.075 m
the knife mass is around 0.096 kg - m
the throwing speed about 3 m/s - V
that the stopping force grows as the blade penetrates the stump in a square power to the depth (for simplicity, it's the friction force, so it grows as the contacting surface grows, the cutting component only grows linear, so we can probably omit it)
that knife gets into the stump to a little less than 1/2 blade length: about 0.03 m - L
we gat the following basic equation:

(m*V^2)/2=(k*L^3)/3
or
0.096 * 9/2=k*(0.03^3)/3

k=48,000 N/m. The maximum stopping force will be F = k*L = 48,000*0.03 = 1,440 N - that is an equivalent of 144 kg weight. So if the knife goes into the stump under say 30 degree angle, we need use trigonometry for some simple calculations... Let's say, it will be equivalent to about 83 kg applied perpendicular to the center of the handle, or half of that applied to the tip of the blade as you hold the knife in your hand. Or you could check the lock vs. blade ratios: I think that would be two-three times that force applied to the lock itself! Do you want to apply around 200 kg force to that small contact area, even if for a very short time? If not: do not throw your folders, even if they go straight in (because it will be like applying 150 kg to it's pivot area)!
Is it a good way to test a lock: I do not think so, considering that it was not exactly designed for that application.
I hope that helps.

P.S. As you can see, the depth is the major factor there. The harder the "stump", the smaller the "depth" that the blade penetrates, the greater the maximum stopping force....

 

[Gator97]

I'm not sure what's the reason some of the people get so frustrated with lock testing.
As far as I am concerned, locks are there for a reason, to protect the user's hand/finger from accidents. You know, those things that happen unplanned, unexpected, unwanted etc

...If the locks fail under ridiculous tests (read: abuse) which they were never designed to withstand how can I tell that they won't just up and close on my hands for no good reason at any time??? ...

Right, so all the lock failures should happen, or are supposed to happen according to strict procedures outlined... where exactly?
According to that logic, there is no need for a lock at all, just make sure never to apply force in the wrong place when the knife is opened and that's all there is to it. Or keep it in a safe.
Well, while we are at it, why do we need seat belts, airbags, bumpers, etc on our cars anyway? Makes them heavier, more costly, etc. It's simple, don't crash, hit anything, etc and you'll be fine.
It's not like people don't do stupid things, but besides that, there are plenty of reasons why accidents happen independent of someone's actions, other than being in a wrong place at a wrong time.

 

[A Justice]

440C @ 58Rc = 22J
S90V @ 58Rc = 26J
S90V @ 57Rc = 16J
L6 @ 57Rc = 92J
CPM3V @ 60Rc = 95J
S7 @ 57Rc = 165J
D2 @ 58Rc = 30J
D2 @ 60Rc = 31J
O1 @ 58Rc = 41J
A2 @ 58Rc = 45J
A2 @ 59Rc = 50J
A2 @ 60Rc = 56J

I see toughness going down as hardness goes down in there... and some places where higher hardness comes with higher toughness in a different steel Amazing! Or not so much. Now show me data demonstrating that the force generated by throwing a hardened knife overcomes its material toughness in the manner you describe. or you can start a new thread on the topic as this isn't really part of the OP.

That's only because you're still within an acceptable hardness range for A2 and D2 to retain most of their toughness. - but what is more concerning, is what kind of testing is that supposed to be? Is it a Catra developed testing procedure/equipment? If it's some kind of rudimentary test developed by the person that made the chart, you need to give a lot more details - and I would venture a guess that the testing is a type that applies only to his variables (if he's breaking 6" blades in the middle, it has nothing to do with anything except breaking 6" blades in a controlled environment, and it isn't a measure of toughness that is universally applicable). He is measuring it in Joules or Work, so it's likely an experiment where he's applying force over a distance - it might correlate to the blade's toughness, but I don't think that's a valid measurement.

 

[MJF]

I'm not sure what's the reason some of the people get so frustrated with lock testing.
As far as I am concerned, locks are there for a reason, to protect the user's hand/finger from accidents. You know, those things that happen unplanned, unexpected, unwanted etc


Right, so all the lock failures should happen, or are supposed to happen according to strict procedures outlined... where exactly?
According to that logic, there is no need for a lock at all, just make sure never to apply force in the wrong place when the knife is opened and that's all there is to it. Or keep it in a safe.
Well, while we are at it, why do we need seat belts, airbags, bumpers, etc on our cars anyway? Makes them heavier, more costly, etc. It's simple, don't crash, hit anything, etc and you'll be fine.
It's not like people don't do stupid things, but besides that, there are plenty of reasons why accidents happen independent of someone's actions, other than being in a wrong place at a wrong time.

By this logic, we should test seat belts and airbags and bumpers by dropping them from 30,000 feet...because, who knows, someone could accidentally drive out of an aircraft in flight.

The point is that locks on knives aren't designed for abuse, they're designed to avoid accidents. All locking mechanisms will fail given enough abuse. Every single one. Taking the results of those failures due to extreme abuse above and beyond the intended use and design for any given lock as proof that a lock type is defective is pretty absurd. All lock types will protect your hands if you're using a knife correctly and for the correct purpose. In my opinion, if you're breaking folder locks which meet the intended specifications for any given model, you're probably abusing the knife or using it for a purpose other than intended and probably shouldn't be playing with knives. Use a fixed blade if you want to beat on something.

 

[dsimmons]

You gentlemen need to get out and use your blades more.

Or maybe people need to use the right tool rather than just act like tools.

Unless you are just framelock fanboys.

Yes, everyone that thinks using tools improperly is idiotic is a fanboy. Grow up.

ALL my use blades are fixed.....

So the truth of the matter is you're only flapping your noisehole because you're a FIXED BLADE FANBOY too scared to use a REAL KNIFE?

Hey, that sentence was as logical and made as much sense as anything you posted.

 

[Yo Mama]

Or maybe people need to use the right tool rather than just act like tools.



Yes, everyone that thinks using tools improperly is idiotic is a fanboy. Grow up.



So the truth of the matter is you're only flapping your noisehole because you're a FIXED BLADE FANBOY too scared to use a REAL KNIFE?

Hey, that sentence was as logical and made as much sense as anything you posted.

Ah, to late, got the hammer for acting a fool.

 

[DarkPatriot]

[QUOTE/]The point is that locks on knives aren't designed for abuse, they're designed to avoid accidents. All locking mechanisms will fail given enough abuse. Every single one. Taking the results of those failures due to extreme abuse above and beyond the intended use and design for any given lock as proof that a lock type is defective is pretty absurd. All lock types will protect your hands if you're using a knife correctly and for the correct purpose. In my opinion, if you're breaking folder locks which meet the intended specifications for any given model, you're probably abusing the knife or using it for a purpose other than intended and probably shouldn't be playing with knives. Use a fixed blade if you want to beat on something.[/QUOTE]

:thumbup: this. The lock isn't there to turn your folder into a fixed blade sharpened pry bar. It's there as a safety precaution. My car has air bags and seatbelts, doesn't mean I should drive it full speed into a concrete barrier.

 

[chiral.grolim]

That's only because you're still within an acceptable hardness range for A2 and D2 to retain most of their toughness. - but what is more concerning, is what kind of testing is that supposed to be? ... I don't think that's a valid measurement.

Those are C-notch Charpy values (you can wiki that), most from Crucible's own website, and Joules or Ft*lbs are the standard units. They apply to cross-sectional area with a deliberate focal point (the notch) built in. The values are generated at various testing facilities and provide a general framework for manufacturers using the material in terms of what to expect for geometries under specific temperature conditions. The range 57-62 Rc (most of the Charpy values are 58 Rc) is standard for most cutting tools because it provides apex strength to prevent plastic deformation in thin geometries, a problem for cutting tools left any softer with a thin edge. The values elucidate differences not only between steels but also within individual steels in terms of what effect different heat-treatment can have on the matrix (e.g. austenite vs martensite) and thereby material properties of the steel. A steel can be made harder and also tougher.

CATRA measures abrasive wear, not impact toughness.

Nice pick and choose to try to prove your point...
A2 and D2, by those charts only has minimal benefits when made harder... not quite a selling point there...

A9
RC58 - 75J
RC57 - 68J
RC56 - 147J

And you notice, the steels with the higher toughness ratings are that of carbon alloyed steels, not stainless...

Material toughness is only a relative idea of how they would perform. It's academic at best and completely theoretical. You're not taking into account non-static shocks and vibrations imposed on the steel. It's not one solitary strike that will cause it to fail, but continued strikes that will erode the structural integrity of the knife. Pretty simple, really.

Look at those A9 values - Reduce 1 HRC point and lose ~10% toughness, reduce one more point and gain 200% ! What do you think will happen if you go down again or up again? In simple carbon steels with minimal alloy it is generally simpler, softer due to retained austenite improves toughness... then again, if the metal torques on impact, there are zones of embrittlement as can be seen charted here:

As for carbon alloyed steels being tougher, did you not see CPM-15V? Look for CPM-9V at hardness above 50Rc - non-stainless carbon alloy steels well below stainless steels. Do you understand WHY they are lower? Why other steels are higher? M390 rates alongside O1 tool steel. It has nothing to do with "stainless", it is matrix composition - grain size and carbide size + volume.

Anyway, material toughness data is generated empirically, just like throwing a knife and seeing if it breaks or not - reality, not theory. Theory says, "it'll break eventually". Fracture propagation requires fracture initiation (nucleation), and where does that come from? First you need to put sufficient energy into the material to initiate a fracture if you expect to propagate it, unless an inclusion is already present (like the C-notch or poor quality steel). As for "vibrations" and the like, without fracture initiation you need to generate substantial force in your elastic deformations (vibration) before you reach fatigue in hardened steel, the limit due to vibration is almost infinite.

It's fine to be paranoid about your own tools, but there is material science literature that supports the strength and toughness of hardened steel for applications where impact occurs. That, and lots of us throw our fixed-blades, have thrown them thousands of times, have had them ricochet and impact poorly, etc. and still not experienced catastrophic failure.

Again, the reason that most $10 throwing-knife sets are softer than 55 Rc is the same as for kitchen knives (obviously not intended for throwing): low expectations of the steel - steel choice, manufacture, heat treatment, quality control, and geometry ALL play key roles.

 

[Gator97]

By this logic, we should test seat belts and airbags and bumpers by dropping them from 30,000 feet...

And you are certain that 6 inch distance the knife traveled before impacting that log is so extreme that the load/forces can not be replicated under different circumstances, like falling, moving object hitting the blade, etc.

The point is that locks on knives aren't designed for abuse, they're designed to avoid accidents.

Correct. What you are assuming though, is that accidents happen in a well defined, established patterns and just because he three the knife short distance it is outside of the pattern you accept as an accident. What if he was holding the knife and someone/something hit it, with a similar angle. Is that a better test then? Because it is more likely or what?
Accidents depending on their nature can be very abusive for the knife, blade, lock, user etc... And what then, we blame user because he got involved in an accident that wasn't in the "accepted" pattern?

All locking mechanisms will fail given enough abuse. Every single one.

So, based on that all tests are meaningless? Or you have a guarantee that accidents that could happen to you and your knife are exactly by spec and lock won't fail?

Taking the results of those failures due to extreme abuse above and beyond the intended use and design for any given lock as proof that a lock type is defective is pretty absurd.

I don't think he said lock was defective. As I read his conclusions, frame lock isn't all that strong as it was hyped. Big deal. You have never seen claims like that? About frame or any other lock?

All lock types will protect your hands if you're using a knife correctly and for the correct purpose.

If you are using the knife correctly and for correct purpose, there is no need for a lock Slipjoints and friction folders have been around for a very long time. It's just the accidents happen and locks were developed, since we aren't perfect and the world isn't either.

In my opinion, if you're breaking folder locks which meet the intended specifications for any given model,

Well, the most informative piece I've seen about the locks was their breaking strength, which is also rare. Other than that, instructions on how to disengage the lock.
So, what are the "intended specifications" for frame lock of any other lock? Yeah, throwing a folder isn't really designed use, however the issue was with the lock, not with broken blades or pivots, which get more abuse on that case.

:thumbup: this. The lock isn't there to turn your folder into a fixed blade sharpened pry bar. It's there as a safety precaution. My car has air bags and seatbelts, doesn't mean I should drive it full speed into a concrete barrier.

Oh I see Now I know, all the accidents that happened, where cars hit concrete barriers at full speed, were caused by their malicious drivers! They simply wanted to abuse(or test) airbags and bumpers, otherwise they would've hit those concrete barriers at the manufacturer specified speed and angle.
I'm just curious, what about the case when someone was just standing or driving and another driver hit him head on, full speed. Those do happen too unfortunately. Blame those unfortunate souls again, for getting involved in "unsupported/unspecified type of accident" or there are other rules?

Car accidents and knife throwing aside, what if your hand slips, or you fall forward, or moving object "accidentally" hits your blade at the tip, with similar angle as in the throwing case, that'd be an accident now, wouldn't it? Is it still ok for the lock to fail, because it was an abuse or how's that gonna work?

 

[DarkPatriot]

No, I get what you're saying, under normal use the knife could experience a similar blow that could cause the lock to fail causing injury. My comment was more towards the guy who was saying if you weren't throwing your knives they were safe queens and we were frame lock fan boys. I'd say the lock should stand up to the sudden impact on occasion without giving, if the knife is subject to repeated sudden impacts you may be using the wrong tool . I also asked if a difference in force resulted in the same failure, in addition to angles other than 90 degrees.

 

[Ramiel]

I decided to test the framelock of my XM-18. I strapped it to a stick of dynamite and then lit the long fuse (because I stayed a safe distance away from the coming explosion, duh). I can't seem to find my XM-18 anywhere now...but I'm pretty confident that the lock held secure. It's designed for hard use after all. I'll go back to searching for my knife now.

In the meantime I think I'm going to take my Griptilian and test the Axis lock by tossing it into an active volcano. When the volcano erupts, I'll find the griptilian and see how the lock held up.

I'll report back to you guys to let you know how my testing went.

 

[Gator97]

... My comment was more towards the guy who was saying if you weren't throwing your knives they were safe queens and we were frame lock fan boys. ...

I'm not advocating throwing folders, don't get me wrong. In tests (designed, or accidental) things can be different in order to model various results, that's all. There are no specified lock mechanism parameters really, so it's kindda difficult to classify certain things as abuse or test, especially that locks by definition are designed to prevent accidents, which are random by nature.

 

[DarkPatriot]

I think it only really becomes abuse when you do it intentionally. The argument can be made however that the intentional in the name of testing is necessary to make sure that if it occurs during normal use the lock won't fail. So in summary, I think at least in regards to your last statement, we're in agreement, Gator.

 

[blue109]

 

[RemyKaze]

Holy crap, I can't believe people consider throwing a knife on a wood block blade first as "abuse". Wow. You gentlemen need to get out and use your blades more. If you have a blade that you "use" and not keeping super safe and sparkly for collecting purposes then you'd realize how ridiculous your comments are. Unless you are just framelock fanboys.

OP, I don't trust framelocks for this exact reason. I use them very cautiously. I didn't think this was such an unknown event in the knife world. Many companies use secondary measures due to this issue. It's not knew. ALL my use blades are fixed.....except my leatherman wave...that gets a pass.

Same opinion of framelocks. And usage. The new ZT Emerson collab will be my first framelock. I actually feel that a liner lock is a bit more secure. I don't throw my folders, but I would like my lock to NOT disengage or collapse if I drop a knife a certain distance, or accidentally overstrike or something similar. Stuff like that happens even when not abusing a knife.