What's the deal with "Lock Rock?"

Daniel Dorn

Daniel Dorn

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Apr 21, 1999
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I've been in the knife accumulating "business" (hobby, pastime, obsession) for near 20 years, now, and it seems like just recently that I've had to deal with Lock Rock.

For those who are new to knives, lock rock is when a liner, or frame-lock doesn't fully slide over to keep the knife still in the locked position. To me, it seems like an issue of not enough bend in the liner, or frame.

My 2 examples are both $300+ titanium frame locks.

The solution these days is to start including stainless lock inserts at the end of a frame lock to be adjustable for "wear."

Is there a reason I saw nothing about this phenomenon until recently? Has it always been an issue? Did we just stop bending the bars over far enough? Were people complaining too much about Lock Stick?

Let me know your thoughts...

Anyway, it was an easy fix on both knives. I just took them apart, and put a little hurt on the lock bars to make 'em mind better. No more lock rock, and they didn't complain a bit.
 
My guess it is a combination of two things. #1 many new users coming into the fray and with YTube and whatnot. #2 Knifemakers not designing the lockface etc. the proper way.

Having said that, it's not much of a problem to me.

Something would have to be incredibly bad for me to send something back. I also feel many are so critiquing in the way they go over a new knife that it is a tad silly. if you are just a collector and in it for the investment and eventual payoff.....I suppose that may be different. In just about every purchase of mine it takes time for a knife to break in, there have been two that seemed to not require a break-in period and coincidentally they are my cheapest knives. Different knifemakers and the way they put it together and the types of material they use takes time for everything to seat together properly. But when it does it is a thing of beauty IMO. Lastly I will say if people would look at their knife as a tool and actually Use It (what a concept) like the knifemaker intended it to be then I think it wouldn't be much of a problem.
 
If you develop that in a well-used Strider, just send it back. They will put in a slightly-larger stop pin, and your knife is good again for twenty years.
 
Emerson fixes it for free as well. I've only had one Emerson with lock rock, it lasted 7 years.
 
Lock rock is because the lock doesn't seat perfectly against the blade in the open position. This can be from tolerances being slightly off, or because the lock has worn down to make enough room for wiggle. Usually a lock with a little play isn't an issue, but it can very well be a precursor for a lock that can be forced through easier than it should be. For users, a little rock lock is not usually an issue so long as it doesn't make the knife unsafe, but it is usually bad for collector knives.
 
I've just sent a Mnandi back to CRK as the lock would slide over, but even just a light amount of pressure on the spine causes the lock to slip off and blade to close on you. And no, I've never done anything goofy like whack on it or anything. I found out by accident actually while I was cutting some cardboard and ended up at a weird angle and the blade almost closed on my fingers. I felt it slip and stopped so I wasn't cut. Which is actually an anomaly for me as usually I can just walk by a knife laying on the table and cut myself. Lol.

First time I've had an issue at all with a CRK product. But I'm confident they'll fix it right up for me.
 
I would have to agree with glocker199 in that it is (usually) titanium caused issue. It can be mitigated by not waving too much or heavy wrist flicking but with enough use the TI will eventually wear down.

MrPocketsOfSteel said:
In just about every purchase of mine it takes time for a knife to break in, there have been two that seemed to not require a break-in period and coincidentally they are my cheapest knives.
Click to expand...

I believe that. My brothers Kershaw/Emerson was nice and smooth right out of the box where all the Emersons I've had needed some time.
This can be very true with other things like baseball gloves. You can go buy a glove at WallyWorld or Sports Authority and go play a game with it that day. If you bought a higher end glove like a Rawlings Pro Preferred you would need to give it a good amount of love before that thing is game ready.
 
Oh I forgot to add that a steel insert is used on aluminum and titanium locks because both metals will wear much faster than steel when rubbing against steel. They are lighter and tougher, but softer and less abrasion resistant. The steel insert gives you the weight savings without the faster wear. It also makes the lock modular, so if it wears out you just gotta get a new insert and you are good to go.

Steel inserts also help prevent lock stick, because titanium and aluminum can deform against steel, while steel on steel should have little to no deformation.

I know for titanium locks specifically, the face can either be hardened or carbidized to substitute for a steel insert. Of course a properly made titanium lock shouldn't have issues, the steel insert just makes the issues generally less likely.
 
Here is a video I made of lock rock...

[video=youtube_share;azolYvoupt4]http://youtu.be/azolYvoupt4[/video]
 
I've seen and fondled quite a few knives (like most people on this KNIFE forum : D ) and my take on the problem is two fold. First I am not sure that thin, untreated titanium is the best material in any hard use folder with a liner lock. Second is that (as mentioned earlier) some makers/producers doesn't really care how the lock is cut.

Untreated Ti is soft, a blade is maybe 10 points harder. It is self evident what will happen when those two materials meet, be it pressure or impact one of them gives.
 
Smokinape said:
Here is a video I made of lock rock...

[video=youtube_share;azolYvoupt4]http://youtu.be/azolYvoupt4[/video]
Click to expand...

My user ZT 0780 has just a bit of what you show in the video; under pressure, the liner will slip just a bit on the blade lockface, but stops short of slipping off. I don't see it as a problem on my user, and my safe queen 0780 is perfect.
 
It has nothing to do with titanium and everything to do with lock geometry.

Ss inserts are cool and can double as over travel stops but I have never had a properly designed framelock wear so much it had lock rock even after many thousands of openings.

A poorly executed lock interface with an ss insert will still have lock rock.

Lock rock CAN develop over time through wear, yes and that's understandable. But 99% of the issues I have with lock rock are with knives new from maker.
 
That video does not demonstrate lock "rock". That shows lock "slip", although none of this really matters just stating there is a difference (semantics, I know). Typically, when a lock bar does not exert enough pressure on that results in blade "play", although it can be or feel like rock. The rock usually occurs from incorrect geometry. Usually one of two things. One being the face of the blade tang contacting the bar too early and/or too much (ie the very front of the blade tang should hit the lock bar and nothing else). This will cause it to roll on the lock bar face. The contact point should be as far forward as possible (again, front of the blade tang, the lock bar point can be center of the lock bar). I believe CRK is the only one to have (really) perfected the art of having more than .090' contact surface. The second is having the contact point on the tang in a position that causes the lock bar to want to move towards the back of the handle. Just think of an arc. If you have a skinny lock bar and move the lock contact point all the way to the front of the lock bar you can visualize how it would want to move backward when "negative" forces are applied. No more quotation marks for for the rest of the day. Whew.
 
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