Lock strength? CBBL, RIL, Mid rocker lock, power lock etc.

[Wanimator]

I'm interested in the strength of the locks that Spyderco uses, I mean, I know stuff like the CBBL is super strong but I'd like to know numbers/see scientific tests to get exact-ish numbers I know that the Axis takes 600 pounds of force. Not that I'd ever apply 500+ pounds of force on a knife, it's just a topic that interests me, not to mention it's quite a feat of engineering.

[Blerv]

Spyderco's lock ratings are in pounds per blade inch. Anything in the "extra heavy duty/MBC" category (most comp locks, CBBL, heavy duty frame locks, etc) is over 200lbs per inch of blade length. So in the case of a PM2, a proper functioning example if put to the lock breaker should at LEAST take a static 701lbs of force, likely much more. We also know they do spine whack tests.

It's very unlikely we will see released data. It's not really accurate for our own use (since we don't have lock breaking machines) and it's more liability than it's worth. That and Spyderco doesn't seem to capitalize on the sensational.

[Wanimator]

So things like the Manix 2 XL would be rated at around 750-800 pounds?

[Blerv]

Yep from a product testing perspective. They build them to be at least that strong so it would be a safe guess.

There will always be occasional flukes in manufacturing but the unsafe ones that get past QC are few and far between.

[WorkingEdge]

Just seeking clarification. I would think it should be rated as how much torque is required to defeat a lock. For instance, 200 pounds 3 inches away from the pivot is equal to 600 pounds 1 inch from the pivot. Is there a link for these values, Blerv?

[Laethageal]

Interesting information, but how useful is it in reality?

[Blerv]

Just seeking clarification. I would think it should be rated as how much torque is required to defeat a lock. For instance, 200 pounds 3 inches away from the pivot is equal to 600 pounds 1 inch from the pivot. Is there a link for these values, Blerv?

Good question, wish I knew the answer :o. As I understand it they just engineer for a rating of lbs x inch and apply that to the machine doing the breaking. That or I'm not extrapolating the past statements in the correct way.

Interesting information, but how useful is it in reality?

Not really useful for the end user. Really useful for a company trying to make the lock match the philosophy of the model design. I've yet to break a lock though might not be the best to comment on that :).

[Cliff Stamp]

For instance, 200 pounds 3 inches away from the pivot is equal to 600 pounds 1 inch from the pivot.

Not exactly, there are two things going on :

-the torque generated at the fail point
-localized strain because of the load

Thus a very high load could generate failures from the second type even if the torque was low. It is easy to understand this in extremes, just imagine a load of several tons right next to the expected rotational point of failure. It is very likely that direct deformation will be a failure mode when loads get very high. This is why you want to adjust the distance so the loads you apply will approximate loads in use as if you make the distance very short then it is unlikely the failure modes will be anything close to what is even an approximation of real failure modes.

If you want some actual numbers, Spyderco used to post them on BF, the original numbers are still there as is lots of discussion about it (see for example : http://www.bladeforums.com/forums/showt ... ost3419609" target="_blank ) .

They (Spyderco) were part of the lock wars of the early 2000's where everyone was racing to get (and promote) a 1000 in.lbs lock . It fell away for a number of reasons, significantly a number of people like Joe Talmadge and Steve Harvey showed that there did not seem to be much correlation between a lock having a very high static load failure and a lock which would actually collapse in use.

It was possible to get a lock with an extreme slow load failure point which would collapse under what you would consider trivial cutting and of course light to moderate impacts. Benchmade has started promoting it again recently, Cold Steel does as well but also does impacts on both blade directions.

[Johnnie1801]

Bladehq tested a few cheaper knives earlier this year, I wouldn't want to do this with any of my knives :eek:

[sal]

Hi Wanimator,

We have a purpose built breaking machine for all types of breaking. Logged into a program that does a variety of measuements on the break and we use prohotograohy to record and study the break frame by frame.

We have our own internal standards that we use for each model.

Keep in mind that all locks are good. Reliability being far more important than ultimate strength. Strength is a matter of adding enough material to drive the number up to spec. Thicker or a different material are the directions we go to increase lock strength. Sometimes we have to "re-invent" the lock.

sal

[ABX2011]

For practical purposes, lock reliability is far more important than lock strength.

[Blerv]

Another factor is application per knife. I've had quite a few frame locks that were not trustworthy (by at least assumption and price bracket) but never have had a Spydie fail. Not that it can't happen but you have to trust the maker of your product. If you don't the next thing is to reclassify the tool for lighter/safer tasks.

[bdblue]

For instance, 200 pounds 3 inches away from the pivot is equal to 600 pounds 1 inch from the pivot.

Not exactly, there are two things going on :

-the torque generated at the fail point
-localized strain because of the load

...

If you want some actual numbers, Spyderco used to post them on BF, the original numbers are still there as is lots of discussion about it (see for example...

The specifics in that thread are a bit hard to interpret because the units are used incorrectly. If you apply 200 pounds at 3 inches from the pivot, you have applied 600 inch-pounds onto the system. (And yes 600 pounds applied at 1 inch from the pivot is the same external force but does cause different internal forces on the individual parts of the knife.) The old thread mentions forces in inch/pounds which is not real units for any discussion of forces. (Torque, or bending moment, is force times distance.)

If the old thread is intended to say that they apply 200 inch-pounds per inch of blade length then that would mean they would apply 200 pounds of force at the end of the blade, 800 inch-pounds on a Military for instance.

The discussion of lock strength is only part of the story. The strength of any individual knife is partly due to the type of lock and partly due to how the lock is implemented in that particular knife. For instance the BBL, the bolt action lock and the compression lock all put a solid piece of metal between the tang and part of the knife frame so should all be pretty strong, but the force that transfers from the blade tang through the lock device has to go into a stop pin, backspacer, whatever. At failure this blocking piece has to fail or its attaching screws have to fail. This would be heavily dependent on the shapes, thicknesses, etc. of the pieces. The exact shape of the blade tang could also be important- for instance at the same applied load on 2 different blades, the forces transferred to the lock mechanism could be different. So it is entirely possible for the lock design to be good but the implementation on a specific model could limit its strength.

I never worried about lock strength and felt like the simplest liner lock was plenty strong for me. Then recently I bought a cheap knife brand to play with and noticed when applying force to the blade the end of the lock bar would move sideways across the tang. This was not very confidence inspiring, so again it seems that the implementation of the lock is more important than the lock type itself.

I've seen a video of another knife brand being tested, and I would like to see similar tests of a few of the bigger Spyderco models, but if Sal says that they test them then I'll accept that if they pass Spyderco's tests they are probably more than suitable for anything I'm going to do with them.

[bearfacedkiller]

I prefer the idea behind the cbbl, compression lock, bolt action lock and even axis lock. The force is applied in a manner that it basically has to crush something against a stop pin or similar. I believe one thing that is over looked is that some lock designs are easier or harder to inadvertently disengage during use. When cutting aggressively I feel as though a frame lock and to a lesser degree a liner lock could be disengaged while wrenching on the knife especially with gloves on if the glove was able to work into the frame a little. I have never personally had a lock fail on me during use but I feel as though the compression lock on my para2 and the cbbl on my manix2 would be very difficult to disengage during use.

[Laethageal]

Disengage a frame lock with your glove while you hold the knife in your hand? The tighter you hold it, the further the lock is push in locking position. I never was worried with something like this.

[bearfacedkiller]

Sometimes I push down very hard with a knife while sort of twisting/rocking back and forth while cutting through tough material (frozen fish for bait) and I do not need to squeeze the knife super hard to apply a ton of cutting force. I also find it hard to squeeze super hard with a large winter glove on. In all reality even if the knife were disengaged while doing this it would not be closing. I am a fanatical ice fisherman. :) It is not something I have ever personally experienced and it may be a long shot but I wanted to throw it out there as food for thought. As has been stated, reliability is more important than strength and I just wanted to throw another possible variable into the discussion. Early lockup does seem to be the norm.

[David from NC]

For practical purposes, lock reliability is far more important than lock strength.

I have meaty hands and I've had several knives (some WELL RESPECTED name brands that are considered to be high end production knives) that if I just squeezed tightly I could defeat the liner lock on, so yeah reliability trumps absolute strength. And that was without the stress of stabbing/slashing/prying!