Folding knife lateral strength tests ?

Status
Not open for further replies.
T. Erdelyi said:
Something I learned a long time ago, when you make anything that's supposed to do fill multiple roles you find that it never excels in any.

That's why they say right tool for the right job, prybar to pry, ax to chop, knife to cut, when you try to make one that does it all, something will suffer for it.

Sharpened prybars make terrible scalpels, scalpels make terrible prybars.

Do you see where I'm goin' with this?
Click to expand...

I'm gonna make this whole quote my sigline.:D

I completely agree with you, right tool for the right job. I think a lot of people these days think of tools as the more it can do, the better, instead of I'll just buy one specific tool that only does one job. What happens is you end up relying on that "Acme do it all tool" and it ends up failing you when you need it the most. Kinda like depending on a Champ SAK to do all your camp tasks. It has a tool for every task, but will it hold up? Maybe. But not as good as buying each one of those tools separately.
 
FFK said:
No sir.......$6000 prototype. But I'm sure there are a few folders out that qualify. Not to mention .....there could be interesting results.
Click to expand...

If you had confidence in your knife you would not be scared at all to do it. I know Preston Tucker would have.
 
Every knife will support some side load in a "test" as you prescribe. The questions are (or should be), "How much side load will cause distortion, deflection, and ultimately failure?"

I think another, and perhaps more pertinent question is, "How much force can YOU put on the handle of a knife in this configuration in a practical sense?"

Further, we might want to ponder the implications of representing to a consumer that there is some recommended use for a knife that involves applying some multiple of 45 pounds of force sideways on the handle of a knife.

I get the whole destruction test trend we see in this industry, but when you have to invent new ways to break stuff so you can design a higher level of idiot-proof, I think you are really just creating bigger idiots.
 
For those who may have missed it, the first thread on this concept went over like a lead balloon in General. The thread in Tech Support complaining about that thread being closed hasn't fared any better. Somehow I doubt it's going to soar here where most of the respondents are people who've actually been making knives for years if not decades.

In short, it's a silly idea with very little purpose. Just my opinion, of course.

unit said:
...when you have to invent new ways to break stuff so you can design a higher level of idiot-proof, I think you are really just creating bigger idiots.
Click to expand...

My sentiments exactly :thumbup:
 
FFK said:
No sir.......$6000 prototype. But I'm sure there are a few folders out that qualify. Not to mention .....there could be interesting results.
Click to expand...

You don't have to stress your "$6000" prototype to test your mechanism. It shouldn't cost $6000 to mock up two pieces of metal with holes in them held together by your pivot and cam lock. Stress that, because the rest of your design is really irrelevant at that point.

I think you have vastly underestimated the lateral strength of a conventional folding knife. Reference the link posted earlier. That's for a linerless pinned G10 construction.

Remember. When you see people testing folders to destruction, they're typically esting the LOCK to destruction, not the blade or handle or pivot. The reason for this is that under those loads, typically the lock will fail far sooner than you are likely to see handle or pivot failure. If you turn the knife laterally, now the weak point is no longer the lock, it's the blade. The weak point is still not the pivot or frame construction.

Also, how does the FFK lock respond to wear? Is it self adjusting over time? How does it respond to contamination? Dip in mud and rinse? Sand and shake out? How will the large closely tolerances mating surfaces you have designed for strength react to contamination or wear? Things to ponder.
 
Last edited:
Another question I have how does dirt and debris affect the locking mech? In order to keep the rigidity to have your strength you need right tolerances, as we've learned before on many mechanisms with moving parts, the close spec leaves no room for pocket lint or debris of any kind.

Designing any mechanism requires consideration of the worst possible environment for use, dark, wet, sandy, muddy, with oversize gloves on.
 
Last edited:
I'm sorry, but I completely agree with James......This is one of the dumbest threads I have seen in a while. The info and argument was already thrashed out, why start it again here expecting different results? If it goes down the path of the other one it is replacing, it will get closed, too.

Tip from the Mod to the BF crowd- If it is a silly thread....just hit the BACK icon and don't reply.

Also, I have had someone say this is a sales thread, and that FFK is advertising his FFK knife. He has purchased a knifemaker membership and has the right and privilege to post about his products as long as cost and selling is not what the thread is about. If it gets closed, it will be because of conduct in the thread
 
Last edited:
FTO_dude,
I started this thread to talk about side loads on current folder design. Not my FFK design. For now the last FFK prototype serves me better intact. Later when I don't need it I will hang 200 or 300lbs sideways and watch the blade snap. Maybe you guys might have some other ideas for lateral strengthening. I'm sure the Blade Forum membership would love to hear them.
 
My attempt/solution to increase folding knife lateral strength does not have to be the only one. We could discuss alternate washer materials, DLC, liner

geometry, bolsters geometry, blade tang geometry.
 
I've carried slip joints for nearly 50 years & made them for half that time. Make linerlocks also, but rarely a blade over 1/8" thick... I just do not see the need to clamp one sideways in a vise and hang 90+ lbs of weight on it? What am I missing here???
 
T. Erdelyi,
The overcenter cam lock was invented by an Italian gentleman in 1932. It has a long history(well before many of you were born) and has been

used successfully in just about every condition imaginable. It slides into and out of overcenter lock position. Debris is not a problem. As far the FFK tang lock

geometry, it has crossectional slanted mating surfaces and cavities for crushing and removing debris.
 
Stop focusing on lateral strength tests and all that ish. The board has decided in all of your threads that it's pretty much a moot point for them. They are not only knowledgable about the subject, they are actual users of knives and your potential customers.

You have a very sturdy, cool looking and mechanically sexy lock design. It's unique. Understand that nobody really cares much about the strength and drop the subject already...

Focus on making the knife proper around it and market the mechanical sexiness. I love cool mechanical things.

BTW, are you located in the US?
 
For now the last FFK prototype serves me better intact.
Click to expand...
Thats quite clearly the opposite of the truth. You said in the other thread you have 5 prototypes!?

But, lets speed things along.
I believe you. I believe the FFK(Folding fixed knife?) has the strongest lateral strength of any folding knife in the world.....

Big freaking deal.

You know why no-one tests it? Because it doesnt matter.
You're the first person in the history of knives to think this is a problem.
And its not a problem. Assuming you read the link i posted, we witnessed the simplest possible pivot configuration withstand far more lateral stress than any knife has ever been subjected to in real world conditions.
Every second person in either of your threads has pointed out that your blade will break long before your pivot.
Its a monumental act of trollery(trollmanship?) to continue to the point you have. Let alone spending $30,000 on prototypes for props.
 
Last edited:
Don Hanson III said:
I've carried slip joints for nearly 50 years & made them for half that time. Make linerlocks also, but rarely a blade over 1/8" thick... I just do not see the need to clamp one sideways in a vise and hang 90+ lbs of weight on it? What am I missing here???
Click to expand...

The only "need" exists in the mind of knifemakers and users who fantasize about needing their knife to be a prybar or used as a step used to scale a tree or wall :)

Funny thing is...If you had a tiny baby pry bar the length of a knife it would not expect to be used to against 90lbs.
 
I have a great temptation to go out to the shop and take three pieces of 1/4" D-2. I would make one into a huge Warncliffe blade and the other two into big solid frames. Run a 1/2" schedule 8 bolt through the assembly as a pivot and use 1/4" bolts and standoffs for the frame. Put a big wing nut on the pivot to "lock" the blade open or closed. I could put it in The Exchange for $10 and market it as a bullet proof folder that can take hundreds of pounds of side load....Problem is it might sell and I would have to make another......probably a bad idea.
 
bladsmth said:
I have a great temptation to go out to the shop and take three pieces of 1/4" D-2. I would make one into a huge Warncliffe blade and the other two into big solid frames. Run a 1/2" schedule 8 bolt through the assembly as a pivot and use 1/4" bolts and standoffs for the frame. Put a big wing nut on the pivot to "lock" the blade open or closed. I could put it in The Exchange for $10 and market it as a bullet proof folder that can take hundreds of pounds of side load....Problem is it might sell and I would have to make another......probably a bad idea.
Click to expand...
Man if you could do that with a bubble blowing blade instead of a warncliffe I would pay $20 no problem. Love my Swiss bubble knife but it does have lateral play and it does not lock !
 
Status
Not open for further replies.
Back
Top