Folder Lock: Safety device or something else entirely?

singularity35 said:
So I've read a few guys saying that a knife lock isn't a safety device. If it isn't, what is it then?
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Could you provide quotes or links please? I would like to get the context for which these statements were made.

Common sense would dictate that locks are for safety, but I think the point being made (if I am thinking of the right thread) was that locks on folders, just like safeties on firearms, are mechanical and can fail, and that a person should rely more on what's between his ears to be safe.

This is why I think the whole seat belts and airbags argument is bogus, because those things are designed to protect you from circumstances far beyond your control in most cases, whereas if you put a knife or gun in your hand then you are in complete control or at least you should be and if you're not then that is your fault.
 
For a knife that functions like a slipjoint ( ie back spring) a locking device is an added safety feature. Because the knife is functional without the lock and the blade will stay open without it.
Knives without a back spring ,like modern liner locks, frame locks etc .... it's part of the overall design , without the lock the blade would close.
 
The lock was designed to make folders safer than slipjoints. It's a design feature that is a safety mechanism. Yes it is integral to keeping the knife open, but the design is meant to be safer than a slipjoint precisely because it is designed to prevent accidental closing when force is applied to the spine.

So in the end yes it is a safety mechanism and no locks are not supposed to fail from a simple spine tap.
 
The issue here is a single example of a more general effect.

Namely, "safety devices" often don't risk.

In the most classic formulation RISK = Threat x Impact where,
Threat is the chance of something bad happening and
Impact is the chance of the bad thing causing catastrophic damage.

For example, standing on the edge of a cliff is high risk due the high potential impact, despite the low threat of simply falling over.

Risk compensation theory asserts that the most common outcome of safety devices is that they lower the THREAT but then humans compensate and seek out activities that increase the potential IMPACT. For example, anti-lock brakes lower the THREAT of a skid but drivers drive faster with them, which increases the potential IMPACT. Helmets in impact sports have a similar history - their use correlates with greater speeds which translate into larger potential IMPACT.

As it applies to knives, the same argument suggests that with a lock, users are more likely to twist and torque on a folding a knife in ways they wouldn't if there was no lock. So, while the lock lowers the THREAT of an accidental closing, users use the knife harder which increases the IMPACT if/when an accidental closing should happen.



More here
http://en.wikipedia.org/wiki/Risk_compensation
 
My guess is that it was an offhand comment or not a well thought out comment. A lock is definitely a safety device but the point is that it's one that should not be entirely trusted. i.e. the super wizz bang awesome sauce lock can still fail and thinking that your folder with the wizz bang awesome sauce lock is equivalent to a fixed blade is a bad idea.
 
singularity35 said:
So I've read a few guys saying that a knife lock isn't a safety device. If it isn't, what is it then?
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You will find similar text with many knives from many manufacturers. Even a slip-joint is a "safety device", the divots on a friction-folder, etc., as these prevent the blade from folding closed on the user's fingers when pressure is not being applied to the edge of the blade as it normally is when in use. In use, i.e. cutting, the pressure against the edge of the blade from the medium being cut is sufficient to keep the knife from closing, ANY device which keeps the blade from closing at any time when that pressure is NOT present is technically a safety device.

Regarding a comparison of folders to fixed blades, ever handled a knife with a guard?? THAT is also a safety device. Can a user still cut himself despite these devices? Of course! That does not change their design/function.
 
chiral.grolim said:
You will find similar text with many knives from many manufacturers. Even a slip-joint is a "safety device", the divots on a friction-folder, etc., as these prevent the blade from folding closed on the user's fingers when pressure is not being applied to the edge of the blade as it normally is when in use. In use, i.e. cutting, the pressure against the edge of the blade from the medium being cut is sufficient to keep the knife from closing, ANY device which keeps the blade from closing at any time when that pressure is NOT present is technically a safety device.
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Perhaps we get hung up on what is marketed as a safety device and what is often simply considered a smart design feature with safety implications. The crumple zone on a car is designed to absorb energy in a head-on collision. However, I'm not aware of anyone who is marketing fenders as a "safety device".

Seat belts might fall under "safety device" depending on the bookkeeping of those features. In a commercial aircraft, we might put seat belts under "crashworthiness" rather than "safety", depending on the audience because passenger seat belts don't materially impact the safe operation of the aircraft. Yes, yes, I know people can argue, but, But, BUT! :)

Regarding a comparison of folders to fixed blades, ever handled a knife with a guard?? THAT is also a safety device. Can a user still cut himself despite these devices? Of course! That does not change their design/function.
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And, perhaps there is some confusion over "safety feature" versus "safety device". I would separate them on the basis that a safety device has no other function than to prevent an accident, be it accidental blade deployment or accidental discharge or whatever. A safety feature is a function that is inextricable from another function, usually embodied in the same part, the lockbar on a modern folder, for example. Holding the blade open against spine pressure is a definite safety function, but that same lockbar is a significant part of the structural package that puts a modern folder in the "hard use" category. Or it can be argued that way. I'm sure there are people who firmly believe their penny knives, slipjoints, and friction folders all qualify as "hard use" knives. I can't help that. :) :)

Also, I stabbed my finger last night with a lock-back blade, invalidating locking mechanisms as safety devices! :) :) :)
 
RBid said:
By this logic, training wheels on bicycles, seatbelts, airbags, back up parachutes, and nets under tightropes are not safety devices. After all, they don't prevent activation of the devices they support, instead serving as support in case use goes badly.
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Well, seatbelts on airliners I can see the argument (except for the crew, where the seatbelts keep the crew attached to the seat in bad turbulence). Back up parachutes, airbags, and nets under tightropes don't have any function until we have a failure, so I don't see how you can argue they aren't safety devices. If they had some other function besides saving the life of the daredevil in question after a massive equipment or process failure, I might agree. Training wheels on bicycles are an interesting case, though. I can see them booked as either "training equipment" or "safety equipment". I might double book them in the same presentation, depending on the audience.

[Wait! Now, I will argue that tightrope safety nets and airbags aren't really "safety devices" but rather more in the realm of "crashworthiness" equipment. Aviation is really quite cruel, mentally.]

I think I see where you are coming from. Prevention of accidental activation is pretty much a standard functional description of a "safety device". After all, once the blade is deployed, you can cut yourself! :)

That said, there are other kinds of safety devices. The guards on a table saw, for example, don't stop the saw from cutting, they just minimize the opportunties to cut off your thumb. Still, that guard performs no other function than safety enhancement, so in my world, we'd bookkeep it as a safety device, not a feature with safety implications.

It's interesting to see whose work experience is very black and white on these issues.
 
NeilB said:
... a smart design feature with safety implications...
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This ignores the entire purpose of the "design feature", i.e. safety. It is not merely an 'implication', it is the sole purpose of the feature's invention and implementation. A liner-lock which does not prevent the blade from closing when force is applied from the spine (or in that direction) is NOT a blade "lock" of any sort and serves no apparent purpose in the design other than appearance, despite it having been invented specifically for safety. It is then a "false" lock, much like a "false edge" which is left unsharpened so as not to cut.

NeilB said:
...perhaps there is some confusion over "safety feature" versus "safety device". I would separate them on the basis that a safety device has no other function than to prevent an accident ... A safety feature is a function that is inextricable from another function ... Holding the blade open against spine pressure is a definite safety function, but that same lockbar is a significant part of the structural package...
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There is no confusion, only denial. The lock-bar on a liner-lock is NOT a "significant part of the structural package". One might argue that the blade-stop which prevents the knife from folding backwards during use is a significant structural component, as the knife cannot be used as a knife without it since there is always force against the edge from the material being cut. But any part of the tool preventing the blade from CLOSING during use is an extraneous implementation. A guard is no different, evinced by the plethora of knives lacking guards as well as the very term "guard". The safety feature/device is not simply a feature with incidental safety implications, its implementation stems FROM the safety it provides, just like seat-belts. The knife would still cut without it, it just wouldn't be as safe for the user.

Use an Opinel without the lock. Is it possible? Of course! Force against the edge is transferred to the integral blade-stop (handle) as one cuts. But depending on how tight the pivot is, using an Opinel without the lock can be very hazardous and Opinel states as much, which is why they began implementing it on their knives in the 1950's. This is OPINEL, not Emerson or DPx or any other "tactical"-market brand. A locking OPINEL qualifies as 'hard use' over any knife with a 'false lock' (i.e. liner that does not prevent blade from closing).
 
NeilB said:
Well, seatbelts on airliners I can see the argument (except for the crew, where the seatbelts keep the crew attached to the seat in bad turbulence). Back up parachutes, airbags, and nets under tightropes don't have any function until we have a failure, so I don't see how you can argue they aren't safety devices. If they had some other function besides saving the life of the daredevil in question after a massive equipment or process failure, I might agree. Training wheels on bicycles are an interesting case, though. I can see them booked as either "training equipment" or "safety equipment". I might double book them in the same presentation, depending on the audience.

[Wait! Now, I will argue that tightrope safety nets and airbags aren't really "safety devices" but rather more in the realm of "crashworthiness" equipment. Aviation is really quite cruel, mentally.]

I think I see where you are coming from. Prevention of accidental activation is pretty much a standard functional description of a "safety device". After all, once the blade is deployed, you can cut yourself! :)

That said, there are other kinds of safety devices. The guards on a table saw, for example, don't stop the saw from cutting, they just minimize the opportunties to cut off your thumb. Still, that guard performs no other function than safety enhancement, so in my world, we'd bookkeep it as a safety device, not a feature with safety implications.

It's interesting to see whose work experience is very black and white on these issues.
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"Well, that depends on what your definition of 'is' is."

Verbal jujutsu at its finest.

I guess we'll never settle this without determining the intention of the inventor. Until that day, we remain mired in ever thickening semantic muck, exploring such related topics as, "...and does it really matter, if you can't prove this discussion isn't really a dream?"
 
cncpro11 said:
Could you provide quotes or links please? I would like to get the context for which these statements were made.

Common sense would dictate that locks are for safety, but I think the point being made (if I am thinking of the right thread) was that locks on folders, just like safeties on firearms, are mechanical and can fail, and that a person should rely more on what's between his ears to be safe.

This is why I think the whole seat belts and airbags argument is bogus, because those things are designed to protect you from circumstances far beyond your control in most cases, whereas if you put a knife or gun in your hand then you are in complete control or at least you should be and if you're not then that is your fault.
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There are inevitably variables that are not in your control, no matter what you are doing or holding. Furthermore, seatbelts and airbags don't stop protecting you even if the circumstances are entirely your fault.
 
cncpro11 said:
Could you provide quotes or links please? I would like to get the context for which these statements were made.

Common sense would dictate that locks are for safety, but I think the point being made (if I am thinking of the right thread) was that locks on folders, just like safeties on firearms, are mechanical and can fail, and that a person should rely more on what's between his ears to be safe.

This is why I think the whole seat belts and airbags argument is bogus, because those things are designed to protect you from circumstances far beyond your control in most cases, whereas if you put a knife or gun in your hand then you are in complete control or at least you should be and if you're not then that is your fault.
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Exactly my point.

cncpro11 said:
Thank you, I appreciate that and honestly forgot about it.
I think that thread had lots of folks scratching their heads but I did see the comments and in that context I would definitely disagree.
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Sorry you disagree.

All semantics and engineering aside....

Situational awareness, common sense and personal safety awareness are key ingredients to life. In everyday activities one must practice these in order to not hurt ones self or to hurt others. To not do so is considered "negligence" as defined by law.
It's too bad that these things are such a commodity nowadays that they are forgone in deference to blaming others and create a boon industry in the healthcare and legal system to the point of being burdensome.
 
If I bang the spine of my knife off my forehead a dozen times in a row I am definitely acting like a negligent doofus and ignoring safety standards. That absolutely does not make it okay for a locking knife to fail while I do it.
 
I don't disagree with any of that Karda. Maybe it does boil down to semantics.

I see a "safety device" as making a dangerous thing less dangerous when properly used, not safe.

I trust a good lock, but only so far. I do realize that I'm wagering my fingers on a lock holding up and take that into account when deciding on proper use.
 
Insipid Moniker said:
If I bang the spine of my knife off my forehead a dozen times in a row I am definitely acting like a negligent doofus and ignoring safety standards. That absolutely does not make it okay for a locking knife to fail while I do it.
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But it doesn't make it the manufacturers fault either........

spketch said:
I don't disagree with any of that Karda. Maybe it does boil down to semantics.

I see a "safety device" as making a dangerous thing less dangerous when properly used, not safe.

I trust a good lock, but only so far. I do realize that I'm wagering my fingers on a lock holding up and take that into account when deciding on proper use.
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And that is what I've been trying to say.

The folding knife lock mechanism was never designed to be a failsafe against abuse, negligence or idiocy.
Personal responsibility for usage and ones safety should be acknowledged. Safe practice should be paramount and foremost in knife usage as well as in any life endeavors.
 
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