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What is the point in an integral comp lock?

Random Dan

Random Dan

Joined
Jan 21, 2012
Messages
2,235
Just looking at pics of the ATR recently got me thinking.
For a traditional liner lock, force is directed down the length of the lockbar. Increasing the thickness of the lockbar (relative to its length) by making it an integral lock thus makes it less likely to bend or buckle. As a result you have a stronger lock.

On a compression lock however, the only part of the lockbar that is subject to the force of the blade closing is the little tab at the end. So what's the advantage to making the whole lockbar thicker, when you could just make the part in between the tang and stop pin thicker? Strength should be the same either way.
 
Increasing the thickness also increases the surface area that is affected by the forces acting on the blade and lock, which makes the lock stronger.
 
jnich005 said:
Increasing the thickness also increases the surface area that is affected by the forces acting on the blade and lock, which makes the lock stronger.
Click to expand...

But still the only part that has any force exerted on it is the tab that fits in between the blade tang and stop pin. Making the rest of the lockbar thicker does not add the strength.
 
That may be the reason the current iteration of the comp lock is still in use and the integral models are discontinued.
 
Think about the term "compression" lock. Even though it's just the tip as you put it, a thicker tip is going to be that much harder to deform by "compression". Is it a needed improvement? Doubtful, but I for one would love to have a Ti ATR.
 
Officer's Match said:
Think about the term "compression" lock. Even though it's just the tip as you put it, a thicker tip is going to be that much harder to deform by "compression". Is it a needed improvement? Doubtful, but I for one would love to have a Ti ATR.
Click to expand...
You could make just the tab thicker though, and leave the rest of the lockbar thin to save weight. That would probably be more costly to manufacture though.
 
Just as a RIL's lockbar is more difficult to bow than a liner lock's, it's possible that the thicker lockbar of a compression framelock is better able to resist both compression and twisting. Or, it could just be a way of catering to the folks who like the "bare bones" look of a framelock.
 
It's cool. They probably wanted to prove to themselves it could be done. Some may want a Ti handled knife that is more simple in construction. I cannot think of a full Ti handled SS linerlock knife. If you want Ti handles, than do an integral version of said knife. If/when Spyderco decides to do a full Ti Para Military, it will be insane. The demand for them will go through the roof. Also, if you go Ti you would need a thicker locking tab because the compression strength of 420 SS for example is 50% more than the compression strength of 6Al4V Grade 5 Ti. Ti is not quite the super alloy many think it to be. It gets used more for its corrosion resistance and its comparatively lower density when steel is also a candidate. You cannot harden it to the levels of steel, and it will deform easier than steel. My ring is Ti and you wouldn't believe the nicks in it, it is way softer than steel. Aerospace uses it along with Al and Mg alloys mainly for weight concerns.


I would actually like to see a controlled failure test of a compression locked knife. The actual tab may get smashed, but I am not sure where the failure would normally occur. I doubt the tab would get sheared, the liners would probably get ripped out of the handle.
 
The same question can be asked of a frame lock. Remember, force may be linear and run down the length of the lock, but frame locks have a big cutout of the lockbar to make it possible to close the darn thing. Making the bar any thicker than that does nothing to increase strength, it just increases the size of the contact patch mated to the blade tang and, perhaps, increases comfort of the handle.
 
Insipid Moniker said:
The same question can be asked of a frame lock. Remember, force may be linear and run down the length of the lock, but frame locks have a big cutout of the lockbar to make it possible to close the darn thing. Making the bar any thicker than that does nothing to increase strength, it just increases the size of the contact patch mated to the blade tang and, perhaps, increases comfort of the handle.
Click to expand...

Your comparison of a R.I.L. to the Compression lock is not valid. A compression lock will not fail by having the locking tab slide thus unlocking the knife, it gets more secure as you apply more force (compression force) on the opened knife. Try vicing up a PM2 and put varying amounts of compression forces on the lock and try to force the tab over simultaneously. That is the beauty of the CL, it is not simply an upside down liner lock.
 
nccole said:
It's cool. They probably wanted to prove to themselves it could be done. Some may want a Ti handled knife that is more simple in construction. I cannot think of a full Ti handled SS linerlock knife. If you want Ti handles, than do an integral version of said knife. If/when Spyderco decides to do a full Ti Para Military, it will be insane. The demand for them will go through the roof. Also, if you go Ti you would need a thicker locking tab because the compression strength of 420 SS for example is 50% more than the compression strength of 6Al4V Grade 5 Ti. Ti is not quite the super alloy many think it to be. It gets used more for its corrosion resistance and its comparatively lower density when steel is also a candidate. You cannot harden it to the levels of steel, and it will deform easier than steel. My ring is Ti and you wouldn't believe the nicks in it, it is way softer than steel. Aerospace uses it along with Al and Mg alloys mainly for weight concerns.


I would actually like to see a controlled failure test of a compression locked knife. The actual tab may get smashed, but I am not sure where the failure would normally occur. I doubt the tab would get sheared, the liners would probably get ripped out of the handle.
Click to expand...

You make excellent points here. I wonder, would a Ti compression lock be prone to wear like a Ti framelock and develop lock rock over time?
 
jstn said:
You make excellent points here. I wonder, would a Ti compression lock be prone to wear like a Ti framelock and develop lock rock over time?
Click to expand...

I would guess possibly. As the locking tab slides over it has steel on top and bottom that it interacts with. The fact that it has two surfaces to wear is a plus though. I wouldn't personally be worried about it at all if I was lucky enough to find an ATR in Ti.
 
nccole said:
Your comparison of a R.I.L. to the Compression lock is not valid. A compression lock will not fail by having the locking tab slide thus unlocking the knife, it gets more secure as you apply more force (compression force) on the opened knife. Try vicing up a PM2 and put varying amounts of compression forces on the lock and try to force the tab over simultaneously. That is the beauty of the CL, it is not simply an upside down liner lock.
Click to expand...

Yes, I get that, I'm pointing out that a thicker lockbar on an RIL doesn't serve the purpose that most think it does. The bar isn't any stronger because it has an innate point of failure in the cutout. A thicker bar just gives you a greater point of contact on the blade tang and a more comfortable handle.
 
I see. I would think a thicker lock bar should create less likely hood of rock lock, and the need for a steel insert though, but get your point about it not ensuring a less likely hood of a failure.
 
Random Dan said:
But still the only part that has any force exerted on it is the tab that fits in between the blade tang and stop pin. Making the rest of the lockbar thicker does not add the strength.
Click to expand...

And that tab is likely thicker due to the increased thickness of the ti. I don't have one so admittedly I can't say anything for sure. Put a penny in a vise, then put a washer twice as thick. One is much easier to fold or crush than the other. This is very simmilar to what is taking place in a compression lock with a 1mm tab vs a 2mm tab for example. The beauty and genius of this lock is that the spring doesn't take much if any force because of the wedge effect. It's an excellent lock in my eyes.
Thanks
Jon
 
It's likely esthetic and any strength differences would be largely academic. The yield strength of the steel used in the locking tab is high enough that there is nothing to be gained by making the leaf out of titanium (as in the integral version). Compression locks don't fail because the tab gets crushed - something else will fail first (or, more likely, won't fail). I don't think I've ever seen, even on YouTube, a compression lock failure. Lock rock is another matter but that doesn't affect the safety of a compression lock as long as the tab stays between the stop pin and the tang.
 
Dan is essentially correct, but the lock bar is cut from the Ti handle itself (on the Ti ATR), so it would take another procedure to thin out the lock bar, with very little gain in weight reduction. And thinning out the lock bar, except for a tab at the end, would make the lock bar flimsy, probably requiring the addition of something like the Hinderer stabilization screw.
 
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