Sal: Please explain folder strength standards

Bob, sure, it is one data point. Nothing more, nothing less.

1176 inch pounds 2.4 inches from the pivot
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Bob are you saying that the torque was 1176 inch pounds and you generated this by applying 490 lbs at 2.4 inches from the piviot - or are you saying that you applied 1176 lbs at a distance of 2.4 inches for a torque of 2822 inch pounds?

-Cliff
 
Cliff
Spyderco did the testing Sal is who you should be asking. I am just relaying what their test results were.

Sals Post
David - the blade is fixed in a "vise like" fixture. pressure is applied directly to the handle. the distance from the pivot pin to the pressure point is measured. The force required to cause the lock to fail is measured and graphed by the computer attached to the breaking machine. The force is multiplied by the distance from the pivot to the pressure point.

Pat (the knife killer) Kelly is the R&D and test man at Spyderco. I belive it was 1176 inch pounds of torque applied 2.4 inches from the pivot. The actual force applied to the lock was 2880 pounds before failure.

There is no doubt that the Rolling Lock is the strongest out there. Spyderco has tested close to everything and so far nothing has matched it.

Sal is very coy at times when reporting. I know that they have tested all their products and many Cold Steel products, the reason Sal states they make a very strong lock. A Sebenza and many others.One knife has surpassed 1,000 inch pounds of torque The Rolling Lock. For some reason you want to somehow find a falut with this.


Bob Taylor


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Some days it's not worth chewing through the restraints and escaping.
 
Mr. Taylor, I don't think Mr. Stamp (or I, for what I'm about to say) is trying to find fault with the lock or the testing. But, I shouldn't be speaking for Mr. Stamp anyway.

My problem is the way the test results are being worded. IIR my structures and statics classes correctly (and I may very well be smoking dope here), if you say that 1176 in-lb of torque was applied 2.4 inches from the pivot, then you have an entirely different loading on the pivot (I think a shear load on the pivot pin). If you are applying 1176 lbof force at 2.4 inches from the pivot, then you're causing 2822.4 in-lbof torque on the pivot. If you are applying 490 lbof force at 2.4 inches from the pivot, then you are causing 1176 in-lbof torque on the pivot. In either case, it is an impressive lock. So far, I'm totally confused (and probably totally infuriating you with this post; please forgive me) as to which is being done. And, please believe me, it is not that I don't think that the rolling lock can take it. I'm just trying to understand WHAT it is that it is taking. FWIW, I just recommended to a friend today - who is interested in buying a nice, high quality knife - that the REKAT was probably the strongest knife out there (guess I got that right anyway), even though I don't own one. I figure with both the axis and the rolling lock out there (that Sal would have to purchase the right to use either on his Spydies) he's probably gonna go with the best. It certainly sounds like he's going for the rolling lock. I think we're all just trying to understand the numbers.

Sorry for such a long post, all.


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Live fast, die young, and leave a good looking corpse, it's the only way to win.
Outlaw_Dogboy




[This message has been edited by Outlaw_Dogboy (edited 20 May 1999).]
 
OK, I know the Sebenzas are way out of the REKAT/Benchmade/Spyderco price range but Sal said the one he tested did very well.

Does anyone know how it failed or how much torque/force/mojo/whatever was necessary to cause the failure?

Jon
 
Yes, as Outlaw_Dogboy noted there is a problem with the way the numbers are being quoted, the units don't make sense.

-Cliff

[This message has been edited by Cliff Stamp (edited 20 May 1999).]
 
Cliff and Outlaw_Dogboy
Spyderco has a machine tester which holds the blade in place. Then they measure 2.4 inches from the center of the pivot. A ram which is calbrated and computer graffed then applies inch pounds of torque in a direct constant to the handel of the knife. They then increase the pressure until the knife fails.
Sal might be able to clear this up a bit more from my conversations I have had with Pat Kelly and being in his lab I belive that A pioneer took 1176 inch pounds of torque applied at 2.4 inches from the pivot.

Sal will not tell me the figures on someone elses knife but I know it was well below the Rolling Lock. I have always said the Sebenza and the Axis Lock are more than sufficent for anything you wish a folder to do.

Bob Taylor

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Some days it's not worth chewing through the restraints and escaping.
 
Bob, thanks for clearing that up. So that is about 490 lbs of force being applied. Well that's strong enough for me. I will definately keep an eye on the REKAT rolling lock folders.

By the way you might want to change the quote on your webpage "hold well over a thousand pounds" as that implies that over a thousand pounds is being applied to create a torque which is not the case.

-Cliff
 
Now you can sede why it is necessary that we move slowly. We do not want to be the "authority". we just like to know how and what is happening in the marketplace and how we can improve our own knives. Our tewstws were never designed to "go public". We did some testing for Bob (which we will gladly do for any company). One of the test pieces was the highest we'd tested (490 force).

This is why I would like to get you (forumites) assist in creating an acceptable standard. Quoting actual numbers cannot work for the obvious reasons. I was wrong to quote the numbers I did. At this time I will only quote numbers within ranges (or keep my big mouth shut). This will keep us from being put into the position of having people argue with us or each other over our test results. The last thing we want is flames.
sal
 
I'm sorry if my post will annoy many of the forumites, but my personal opinion is that this whole thing about lock strength is getting paranoid.

If you want to do pull-ups, go to the gym.
If you want to whack tables and chairs, get a police baton.
If you want to compare "yours" to the "others", you can compare the horsepower of your cars or the length of your boats, not the nominal strenght of your folders' lock.

I own many folders, and I don't think I have the muscular power to beat the lock of any of these with my bare hands without using tools or levers (maybe I'm not strong enough)


BUT lock strength and folder strength for me is being able to use my knife as hard as I like WITHOUT THE BLADE DEVELOPING SIDE BY SIDE OR VERTICAL PLAY AFTER HARD USE.
I cannot stand any slack in mechanisms, this annoys me very much, and in a quality knife it is a fatal sin-I'd rather throw it away than have to use it like that.
So, that's folder strength for me, but anyway opinions are like a*********s, everybody has one.

Sorry if I'm a bit poignant this time.

[This message has been edited by Costas (edited 21 May 1999).]
 
Some people do like to compare the horsepower of their cars and the length of their boats, relative to what they pay for them. (shrug) I can understand that though I personally tend not to care as much in those areas (I don't have a boat and I generally take public transportation around the city, which lead to...) I do care about the strength of the lock relative to price (and, in Cold Steels' case, the hype).

I find this thread interesting. A suggestion was made in another thread that the Military was perhaps not as strong because of the lack of liners. I curious whether SpyderCo tests include force going sideways against the blade affecting horizontal play (Costas' concern) or the snapping of the handle right at the pivot. I think this kind of pressure in reality would only come from using the knife as a pry bar (an expensive and less than effective one.
wink.gif
) Regardless, it would address the concern about the strength of a "liner less" handle vs one that does have liners.

sing
 
Sal, quoting numbers is perfectly fine if they are quoted precisely. The reason there was dispute here was that it was unclear what exactly the numbers were. There is no reason not to be exact and quote the tolerances unless you want to be able to promote your knives above their performance levels.

Costas :

I own many folders, and I don't think I have the muscular power to beat the lock of any of these with my bare hands
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That would surprise me. Have you tried? The heavy lock standard set by Sal only requires about 125 lbs to pass the breaking point.


-Cliff
 
Hey Bob, Pretty d****d impressive load on your Pioneer. And plenty of blade options as well. I think it just got slapped onto my want list.
frown.gif
wink.gif
Is it still produced with the lever on the front of the handle, or has it gone with the sliding lever on the side, a la Carnivour?

*Sorry for the language. I expected the server to bleep it out. It didn't.
redface.gif

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Live fast, die young, and leave a good looking corpse, it's the only way to win.
Outlaw_Dogboy




[This message has been edited by Outlaw_Dogboy (edited 21 May 1999).]
 
I was wrong to quote the numbers I did. At this time I will only quote numbers within ranges (or keep my big mouth shut) {emphasis mine -- Titan}. This will keep us from being put into the position of having people argue with us or each other over our test results. The last thing we want is flames. sal
Click to expand...

Sal -- flames, aka fire, is a two-edge sword. It can be destructive or constructive, depending on intent. The issue of lock strength is vital especially for us ELU as our safety, no less, is involved. Like it or not, you are an authority in the knife industry. To shut up is to deprive us of the knowledge we seek.

You yourself said it
We are not enemies, we are all knife nuts seeking a greater truth... sal
Click to expand...

I would really like to contribute to this very important thread but am too ignorant to do so now. So I read. And I am sure most do also.

Please continue sharing with us your no-hold-barred data. For the truth is out there...
 
From a manufactuers point of view;

Lock strength is more an issue of minumum strength. Spyderco developed this test to make sure that each of our models met with minimum standards that we determined would be above normal for this size knife used for this purpose.

Test for maximum strength is "fun" for the R&D crew. 400 inch/lbs (force) or above is what we (currently) "believe" ("guess") would be sufficient to be safe for all applicatons intended in the design.

This is no easy accomplishment. Humans are capable of generating a great deal of force. More than one would nomally expect. Especially in emergency (tactical)situations. I'm sure that each manufacturer has their own standards and reasons for what they do and why. I am just sharing with you some of ours.

We are a small company generating our own research. This is difficult and expensive. That is why we will work with companies like Rekat and Reeve, test for them and share info with them. This info in for their own benefit. Not for advertising or sales benefit. Whatever tests one way today, will more than likely be different tomorrow. That is why we test. Those of us manufacturers that are interested in evolving will always be testing higher and higher. We learn.

In the NSX vs Ferrari. Maximums are for our own "jollies".

The ELU needs to "trust" that the knife is safe, especially as sharp as we make our knives. We are extending our best effort to make that "trust" "worthy".

Lock strength is different from lock defeat. Lock defeat is even more important. It doesn't matter how ultimately strong a knife is if it defeats easily.

Just a point of view to share.
sal
 
This might be unrelated, but what is the strongest REKAT knife? The Carnavour? Is the Carnavour stronger than the military? Blade steel plays a factor in the strength of a knife, right? So what about a Talonite bladed Carnavour--the strongest knife on the market?

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"All of our knives open with one hand, in case you're busy with the other"
<OVAL OFFICE JOKE>
 
Stompy - We've only tested a few of Rekat's Rolling Lock knives, more as a favor to them so they can refine and develop. Really can't say which is the strongest.

They tested very favorably. Stronger than any other lock we've tested. Sometimes the steel in the knife makes a difference, but most of the knives that we've tested will destroy the knife before the blade steel actually breaks.

If the blade steel breaks, this generally tells us that the hardness isn't ideal and permits us to go back to the heat treat. It is a deveolment tool for Spyderco.

The Rolling Lock tested stronger than any of the liner locks that we have tested so far, but that doesn't mean that there aren't some out there that are stronger than those tested.

We have 3 new locks in R&D now, all of which seem very promising.

Keep in mind that extreme ultimate strength is not as critical as impact defeat (failing the "Spine-wack" test.
sal
 
Another consideration would be the lateral strength on a folder. I have an old gerber LST that has a sturdy enough lock, but will split apart if the knife is forced sideways.

From what I have read, it seems that the bulk of the knife failures either occur as a result of impact and the knife being used as an awl. I would be curious to know if compressing a knife from point to butt would have different results to the basic test.

YeK

 
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