List locks based on strength

theonew said:
Wouldn't you want a lock bar to be closer to the pivot to minimize the leverage of forces applied to the blade :confused:
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Recalculating moment using the blade pivot a the, well the pivoting point (coincidence) then you have larger force as it goes nearer.

Like if lockbar is exactly at point where I exert a 10 pound force (far from pivot) or similarly at equal distance then the force experianced by lockbar thingy is 10pounds.

If I put lockbar closer then by moment calcs then I double the force by shortening distance to 1/2 of original or 5 pounds.

Basically it gets higher load closer to pivot. I was more focusing on the direction of force as well as magnitude. This is the same principle as my steel reinforcement cutters.

Hope this helps. :)
 
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During stabbing action, the closing force is different for different tip design.

Darn my spelling but a warncliff knife has more closing forces during stabbing compared to a tanto or a clip point. May be different if exceptional designs were compared but for most cases this hold true.

I believe a guard type design is important to prevent traveling of hand to blade during stabbing action. Some folders do not have anything that resembles a guard and is dangerous to stab with these folders.
 
Hi Juramentado,

The question that you are asking is far deeper and more complicated than it might appear.

Regarding locks, reliabilty and strength are two very different questions.

As mentioned, reliability is more important and can be built into any lock design if the design is properly manufactured out of good materials.

Ultimate lock strength is essentially how much force will the lock resist before it yields to the force (breaks).

Most locks can be made stronger or weaker depending on the material strength and engineering geometry. When we create a model, we decide how much strength we seek. We break a proto, see what breaks, and stengthen the part that failed, break it again, increase strength of failed part, etc. until we reach the desired strength. The "weakest link" of the collection of parts that make up a lock will usually fail first.

No opinions involved. Our breaking machine is hooked up to a computer that measures ultimate force and inch / lbs per inch of force. Our standards listed below are "in-house" standards. the computer prints our graphs of the break. Current prodcution models are regularly broken to make sure "nothing has changed".

Heavy duty is 100 - 199 inch / lbs of force per inch of blade to break the lock. This means that a 4" blade (eg: Spyderco Endura) must resist over 400 inch / lbs of force before yielding, in order to be classified as heavy duty.

Medium duty is 50 -99 inch / lbs of force per inch of blade.

Light duty is 25 - 49 inch / lbs of force per inch of blade.

We also rate very heavy duty or what we call MBC (Martial Blade Craft) rating, which is over 200 inch / lbs. per inch of blade length (eg: A Spyderco Chinook is MBC rated. The blade is 3-3/4" long X 200 inch lbs per inch = 750+ inch / lbs of force to break the lock).

Fixed blades are usually stronger and more reliable against folding than folders (if made properly), but are often more difficult to carry due to their length. ("They call them "fixed blades" cuz they aint broke ;))

SD is another very deep question with many factors involved, but that's another discussion.

sal
 
Cotherion said:
If I put lockbar closer then by moment calcs then I double the force by shortening distance to 1/2 of original or 5 pounds.

Basically it gets higher load closer to pivot. I was more focusing on the direction of force as well as magnitude. This is the same principle as my steel reinforcement cutters.
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Yep you're right, wasn't thinking clearly :o
 
theonew said:
Yep you're right, wasn't thinking clearly :o
Click to expand...


No probs mate, I live my life mostly in a daze :)

I totally forgot the compression lock by Spyderco, very hardcore! I got a Titanium ATR and in theory the lockbar (portion which is under compression during resisting closing force(s)) gotta crush or the stop pin has to shear (or lastly the unlikely pivot shear) before it fails. I believe my ATR is MBC rated. Definately one of my most strongest folder yet, maybe stronger than my ZT302.

Thanks mr Glesser for the info, I like data and I'll refer it from time to time. Hope you guys come out with great folders in the future.

PS: Interesting to note that the lockbar pivot pin for the Extrema Ratio and Dark Ops folders (with notable exception of ER Rao and other non-lockbacks) it is very thin/small in diameter under my observation. In theory it should not be too strong until the pivot pin shears. My guess it's no more than 3-4mm thick. Compared to the CS Tri-Ad lock which the stop-pin which is a thick 6.5mm thick I believe the lock strength of these ER and DO folders are not as good as they are assumed.
 
There's really a ton of factors that determine lock "strength", but truthfully, lock "slippage" is more of a problem than lock breaking....

Most people say a lock broke when it actually slipped, but I digress...

A lot of making folders is geometry, ratios and finishes...

I can make a liner lock where it's damn hard to break or make slip by just not making a relief in the lock bar, but good luck moving it over to open or close the knife....

Mainly, you want to look at the following...

On liner locks...

How far over onto the lock face does the lock bar go (I prefer it to go fully on to the lock face but not slide past the 1/3 point on the lock face)?

What is the relief like (example, a .090 liner that has a relief point brought down to .30 is pushing it....)? If the relief is too thin, it will eventually break, if it's too thick, there's too many foot pounds of pressure on the bar at rest and at open/lock and throughout. With too much pressure the bar will start to wear itself where it meets the lock face...

Is the lock face (on the blade) flat ground or channeled....?

What is the finish like on the lock face (a mirror polished lock face can allow the lock bar to slide)...?

How long is the lock bar in relation to the blade? Some makers use a 75% ratio, some use a 66% (2/3) ratio. In other words, some want the lock bar to be 2/3 length of the blade, some want 75% (3/4 the length of the blade). Key here is, too long of a lock bar and you lose lateral strength, too short and the relief has to be too deep to reduce the stiffness of the lock bar...

There's a lot of other factors as well, pivot placement (55/45 is pretty decent), pivot to stop pin ratio/placement, blade length and thickness compared to the liners etc....

Frame lock is basically the same as the liner lock on things to look for.

Frame locks are really not a ton stronger than liner locks b/c even if the frame is .150 Ti, the lock bar recess is going to be roughly the same as a standard liner lock.

The decided advantage to frame locks and thicker liner locks is there's more frame/liner material that meets the lock face, and thus, less possibility of slippage...

Those are the 2 I use the most (as do most folder makers b/c they don't require a ton of machining knowledge to implement) but I've used the button locks on some autos etc... and I've taken apart and played with virtually ever lock type..

They all are strong when properly made and the difference is probably negligible to the average knife user. I always just tell people, it's a knife, you can use it for whatever you please, but if you wanted a pry bar, you might should've bought a pry bar....

Lock mechanisms all have their own pros and cons, a lot of it has to do with intended use....

I know this wasn't a direct answer to the question, just figured I'd chime in...



MT
 
Compression Lock
Axis
Ball
Lock back
Frame lock
Liner lock - although I think the liner lock on the Cold Steel Scimitar is one of the strongest locks ever made by a production company.
 
don't forget the pin lock on that extrema ratio knife. it's essentially a thick metal pin that you stick into a slot cut into the knife and handle. probably not very convenient, but that'd get my vote as the strongest
 
I've been a pretty big fan of the AXIS lock since Benchmade's first knife featuring it (which I believe was the 710...). When it comes to sheer strength, I usually trust it first.

Listed by what I own:

1 - AXIS/Arc Lock (Benchmade/SOG)
2 - Frame lock (Chris Reeve, some Benchmades)
3 - Lock Back (Cold Steel and Spyderco's specifically)
4 - Button Lock (Autos, William Henry)
5 - Liner Lock (Older William Henry, CRKT)
 
1. Kershaw Stud Lock
2. Axis type lock (Benchmade, SOG, Cold Steel, Spyderco)
3. Hawk Lock
4. Frame Lock
5. Lock Back
6. Liner Lock
 
I know the Benchmade Axis lock, the SOG Arc lock and the Cold Steel Ultra lock are all a little different, but I'd put all three in the same category of "type of lock"

Question: Is there a generic term for this type of lock like there is for "liner lock" or "lock back"?
 
Thanks for the reply, Mr. Glesser. That's a lot of great info!

I'm getting a new Endura wave - after having sold my old one to friend - and its nice to know that it's rated for that much force.

:)
 
Sal Glesser said:
Hi Juramentado,

SNIP
Heavy duty is 100 - 199 inch / lbs of force per inch of blade to break the lock. This means that a 4" blade (eg: Spyderco Endura) must resist over 400 inch / lbs of force before yielding, in order to be classified as heavy duty.

Medium duty is 50 -99 inch / lbs of force per inch of blade.

Light duty is 25 - 49 inch / lbs of force per inch of blade.

We also rate very heavy duty or what we call MBC (Martial Blade Craft) rating, which is over 200 inch / lbs. per inch of blade length (eg: A Spyderco Chinook is MBC rated. The blade is 3-3/4" long X 200 inch lbs per inch = 750+ inch / lbs of force to break the lock).
Click to expand...

Great info.

One question: are these ratings published somewhere about all your production models? I had no idea that the Chinook was MBC rated, or even that such a rating existed until I read your post. Seems like that is info that would be useful to the customer wanting to choose a knife.
 
Out of all the knives I own I would say the compression lock. I would like to try out a frame lock though.
 
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