can someone explain the compression lock?

M

migo

Joined
Dec 28, 2001
Messages
243
or do a search for me? the search function just isn't working at all for me, I'm getting a "search failed" error message
 
I think you can just describe it as liner lock that is located at the top of the handle rather than at the bottom.
 
You could describe it that way, but then you'd miss the most important feature of the compression lock, and what good is a description that misses the most important thing to be described? :)

Your best bet is to look at the drawing on spyderco.com. In my opinion, the most important feature of the compression lock is that when stress is put on the lock leaf, the leaf get caught (compressed) between a notch on the tang and the stop pin. This fixes one of the main problems liner locks have: they are unreliable under steady or impact spine pressure, because the liner is free to just move along the blade tang and unlock. With a compression lock, the more pressure on the tang, the more the liner is compressed and stays put. In practice, it seems to work well.

I know it's hard to envision as I described, but go look at the pics and then re-read what I wrote.

Joe
 
I'm still not sure I understand after looking at the pictures, I'm getting the impression that it's locked from both sides?
 
I guess you could describe it that way. See the little finger that seems to jut out of the liner? That gets compressed between a shelf on the blade's tang, and the stop pin.
 
Ah ok, starting to get a bit clearer. I guess I'll still have to see it in person for it to really solidify. Does it unlock the same as a regular liner lock?
 
Yup, although as Blades_Two cogently explained, it is "upside down" -- you release the blade from the back slot of the handle, not the front slot like a liner lock.
 
When looking and the back of the handle, the lock cutout is on the left side nearest you, roughly positioned the same as a regular linerlock otherwise.
 
Apparently, the compression lock is a linerlock located on the other side of the knife (aka spine). But, a linerlock tends to bend when forced, while the compression lock is forced not only to bend, but also is "squeezed" between the blade and the stop pin. Therefore is much stronger. Also, because it is located at the top of the knife, it is operated with the thumb, so it's virtually ambidextrous. It is simple, reliable and strong.
attachment.php
 
The main, and most important difference between a liner lock and a compression lock is the direction of forces when stressed.
A liner lock by it's nature is already being stressed down it's length. When more force is excerted on it via the blade, this new force is also transmitted down it's length, with the theoretical possibility of overloading the lock. "Theoretically" as I have never had one fail on me, and I've had several.
The compression lock on the other had has the same initial stresses as the liner lock down it's length, but any new forces introduced by the blade are transmitted perpendicular to the locks length, so evening out the lines of stress.

A common complaint of the compression lock is the liner can looks too thin. If it worked in the same way as a liner lock this might have some merit. In reality the "thickness" of the liner is measured as the distance between the back of the tang and the stop pin, which is usually in the 5mm to 6mm range. Quite thick for most peoples needs ;)

Spyderco have said that in destruction testing, it's not the liner that fails first, rather the stop pin. Which is quite impressive as the compression lock is only used in all metal handles, or handles with dual steel liners.
 
No more slipping liner locks! As you bear down on the blade, force is sent from the notched tang to the lock bar to the stop pin. Theoretically, if the lock pin doesn't rip out, the lockbar will be compressed down
 
In break tests, either the stop pin is blown out the top, the compression lock is sheared, the tang breaks off of the blade or the pivot pin shears.

sal
 
as a sidenote i'd like to mention that my Spyderco ATR-ss is by far the knife in which i have the most trust in its lock-up, and i've had and have many folders, with locks of all sorts. the ATR uses a "compression frame-lock" which inspires extreme confidence and a bankvault lock-up. by far THE most impressive locking-mechanism in a folder i've ever encountered.

ok, back on-topic now...... :o
 
I looked all sorts of pictures, diagrams, and read descriptions but I didn't fully understand the Compression Lock until I had a Spyderco Salsa in my hands.
 
Hi Garage Boy. The tang broke at about 800 inch/lbs on a Titan ATR. We Re-designed the radius in the tang notch to make it stronger.

sal
 
Not that this really needs any mentioning anymore, but as Yog said the direction of force is totally different, at a 90 deg angle to those in a liner lock to be precise. On dialex' picture the force would come from below and gets transferred through the stop pin to the anvil pin (hence the name I guess), while in a liner lock the force would come from the left - along the pin which can cause the pin to buckle or slip.

The compression lock is awesome! Just my $0.02.
 
Not to mention that it's not only the pressure between the blade and the anvil pin, but also the ressistance of the liner itself, like at a regular linerlock. Therefore, any compression lock is stronger than a linerlock.
 
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