This was an interesting read, but the original question requires so much development of materials, lock engineering and production capability that it is highly unlikely to occur simply due to the amount of research that would have to go into such criteria.
Think about what is necessary for ALL knife locks to work, and then think about what elastic deformation entails, and then ask yourself if you can actually have elastic deformation without plastic deformation creeping in over time. Nominally, hard-use means pushing things to limits of functionality - real or imagined. Pushing elastic materials to those limits is not without cost to the integrity of the material. Locks require relatively strict tolerances, or people complain of lock-rock etc. Plastic deformation and lock integrity are and will always be opposing forces. Even the BBL lock which is an ingenious way of getting around small amounts of plastic deformation will fail upon extensive plastic or even temporary elastic deformation.
Take a look at the materials for virtually every locking face on every knife you've handled for a moment, and ask yourself if the knife's locking performance would be helped or hindered by a millimeter of induced movement of the pivot pin.
I'm not saying that you couldn't invent such a system, but I will say it is silly to demand such a system without proposing REAL, VIABLE options which you have researched and proven because such a demand is honestly quite demeaning to many of the people who spend their days, months, and years working to research and design these wonderful tools for us. They spend their time learning, developing, and researching the question you propose, and quite honestly Spyderco utilizes the best of the developments that they are capable of when intellectual property rights are considered. If you want those things, try to develop them.
Demanding or asking for something is so much easier than developing it. I see a lot of demands here, and a lot of offense taken when people ask questions about the demands, but so few actual ideas about how to do this that the thread can't help but fall into the tailspin that it has.
This wasn't so much a demand or request as it was just a general discussion.
Hard use folder and overbuilt folder are not necessarily the same thing but I think people get the two mixed up frequently. When someone wanted a hammer with a prybar, they didn't weaken the hammer's ability to perform as such in order to fit one in. A good product is purpose built, so one needs to determine, what is the purpose? No matter how durable the pivot/handle are, the blade loses usefulness if ground thick enough to handle the abuse. I just feel that there are better solutions.
I think what is far more interesting than the "hard use" folder market that some people are so hostile towards is the fact that these "hard use" folders can be used to invent and discover new things which can be applied to slimmer, every day task carry knives. Why shouldn't the knives of tomorrow be sharper, lighter, more wear resistant, more corrosion resistant, and stronger?
Once all we had were slip joints, with carbon steel blades, that opened with 2 hands. Then there were early lockbacks. Now we have thumbholes, pocketclips, sharp, corrosion resistant blades, awesome locks, including more refined lockbacks, and lightweight, colorful, and grippy handles.
When some "hard use" knife maker figures out how to make an even stronger or more durable "hard use" knife, that also means that they just figured out how to add more strength to smaller, lighter knives as well. How is that possibly a bad thing? Any new invention in knife locks, steels, and handle materials benefits everyone. You get there by pushing the envelope. To some people, "pushing the envelope" is making the beefiest, strongest folder they possibly can. To others, it's getting the highest possible cutting and utility performance in the smallest and most user friendly package possible. Other knives push a whole different envelope, like the Salt knives and their corrosion resistance. Every bit of it all means the next knife we buy is better. Why can't everybody be friends?
Effectively what you're looking for is a lock with elastic tolerances that maintains its ability to hold the knife rigidly open through that elastic deformation.
What materials are you aware of that would allow for these properties?
Currently, all rigid aspects of a lock are made of hard materials (steel typically, but in the BBL you can use ceramics)
All bendable aspects of a knife are made of FRN - because FRN has some of the greatest rigidity and torsional strength for a molded plastic due to the ultra-hard yet bendable glass fibers impregnating it. These fibers allow the material to bend to a good degree without undergoing severe plastic deformation. Usually, you can tell when you've gone too far because the plastic will lighten and take a set.
What material or combination of materials would allow you to mimic those aspects while allowing for elastic deformation?
Fiberglass reinforced rubbers lose elasticity for stretching while maintaining some impact elasticity. I cannot see them lasting as long due to the need for solvent impregnation over time.
What will you use for a hard surface in the knife for locking faces to mate? Can you even do that?
I would surmise that you would effectively need a tension system for these matters. I cannot see how this type of knife could get away without some form of a spring that holds the blade in locking position: be it elastic or steel. It may even need an engaging pulley system.
They say two minds are greater than one. If we want to discuss this, people should chime in with ideas about how to generate the materials necessary. Something neat might come of it.
Meh, I'm not smart enough to understand half of what y'all are talking about, but I know I don't care for "overbuilt" knives. If, however, a hard use knife simply means taking a "salt" knife (for example) and innovating new ways of making it even tougher without increasing weight and decreasing cutting performance then I'm all for it, as I would imagine anyone would be.
Back off-topic, here's a hard-use grill:
I carry a heavy, underperforming "hard use" knife for tasks I wouldn't generally use my Spydercos on. A better term this would be "hard abuse" or "use-abuse." Say I'm cutting open bags of concrete mix, smoothing a PVC pipe cut, knocking the burr off of an aluminum cut, or batoning some branches off the bottom of the Christmas tree, other tools will do the job but my choice is a solid folder that's relatively comfortable. I can keep it on me at all times and reach for it when I need to separate things instead of cut them cleanly.
If Spyderco wanted to make a very thick FRN Salt with a 4mm hollow-ground blade that might be interesting. Huge pivot, heavy backspring for example. It would fill the niche of a "hard use Salt", I guess. More likely a large handled Salt would be attractive to people with larger hands or who wear gloves who prefer large/wide blades. The "Bluefin" perhaps? :D
Lets think about it like this. Consider we have a knife that has an extremely hard rubber pivot pin, and then the lock bar itself is also made of this material. Under normal use like cutting cardboard and such, it would be rigid enough to feel normal in your hand, but if you tried to pry with it or baton with it, the pivot and lock would at some point begin to flex before they broke or were damaged to the point that the pivot and lock action were changed. Obviously we can't make a lock bar out of hard rubber, but think of how that knife would perform if it were possible.
For the purposes of physics (or engineering for that matter) the word "elastic" just means capable of deforming and going back to its original shape. What you are talking about is most definitely an elastic process.
The pin situation you're discussing involves a lot of challenges - specifically involving torque.
I'm thinking something crazy like bearings riding on top of a small recessed, shallow, hard, ball joint?
Just for fun, friction folders should also get a mention in a hard use discussion. Simple and around for centuries. I've had this Peasant knife for a while, one of my first non-SAK purchases. A partial tang folder that I have no fear of using with abandon (at under $20 who would?)
The handle definitely flexes.
Been really thinking about getting a Svord and grinding it into a smaller wharnie blade.
If an effective cutting instrument aka folding knife that was made to be able to handle some abusive tasks but still remain an effective cutter then what's the problem of that kind of hard use knife and I think link others have said that it would advance knife making technology for new knifes like, umm well for use on like a knife like the mili 2( want the mili2 so bad).
It is a shame the Spyderco friction floder didn't work out. But someone posted about a "Higo" at the Amsterdam meet. I didn't ask about it in the thread, but I really hope this is short for a Higonokami.
Call it the Spyderco Clutch, whatever mechanism you guys come up with.
An interesting idea, but as Cliff hinted, and others have mentioned, it's an issue of force transfer. I'm not sure it's been explained fully, so I'll throw in my version of the explanation in the hope that it's maybe the slightest bit helpful. The is not some oblique way of saying that the question shouldn't have been asked, just a discussion.
The proposed idea is that elastic displacement of the lock (whether this was caused by mechanism or deformation) would prevent this lock from either disengaging or being damaged. Under some threshold, this lock would act as "normal" with minimal displacement, but over this threshold it would deform/displace. For sake of discussion, lets say this force was 100 units. This issue is that this very threshold is the limit of force that can be transmitted through your hand to the blade, that is, in this case you can only transmit 100 units of force through the handle. So if you were batoning wood with such a knife, and it got stuck, and you wanted to twist back and forth until it broke free, unless breaking it free took 100 units of force or less, you wouldn't be able to do it. Any more force you put on the handle would only serve to deform the lock/pivot further. This is why you can pry and egg off your skillet, and yet not pry a stone out of your back yard with a rubber spatula. The egg is under the threshold of force required to deform the spatula, but the rock is over it, so all of your efforts are lost in the deformation of the spatula.
All this, unfortunately, results in us having the right tools for the right job. Tools that have the right ballpark zones of hardness and elastic deformation to get the job done. Composites are an effort to gain the best of both worlds, and a prime reason that FRN and G10 are wonderful scale materials. Even those have their limits. The garden shovel that will gouge your skillet is just right to pry up that rock, and have a shovel and a spatula is far cheaper than trying to figure out a way to do both tasks with one tool. I can, however, appreciate the desire to make things as multitasking as possible, for situations where you might only be afforded one tool.