meaning of a knife term 'lockup'

T

Tberry010

Joined
Sep 16, 2011
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I have been around a while and have a sort of general knowledge about knives but I see a term used here with regard to folders that I do not understand.
The phrase or term is often stated like this;

"blade is centered and lockup is 80%" or 'lockup is 50%'.

What does this mean?

I understand blade centering but not the percentage reference to lockup
 
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it usually refers to how far across the tang the lock bar goes. like I prefer my lock to go about 30-40% when brand new so that after wearing in its 50-60% across the bottom of the blade I think 70+ is a bit to far
 
looking at a liner/frame lock as pictured.
0% would be the lock somehow not even hitting the tang of the knife and sitting to the lock side.
100% would be the lock travelling all the way across the tang and contacting the opposite scale.
50% the lock is centered on the tang.
 
This is the lockup on my brand new ZT 0550.

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A little bit more than I'm comfortable with (at about 55%?)

However, I'm not to worried because I hear that the coating at the tip of the titanium is extremely durable.
 
Aha, he says as the light bulb begins to glow :)

Thanks to each of you for the excellent replies and now it makes sense.

Tberry
 
Follow up question: I've always wondered why it was a problem if lockup is greater than 70%. I have an OD-1 that gets about 10-20% lockup, and I had that one almost close on my hand once, so I get that end of the spectrum, but what's the concern if it was say 90%?
 
The farther the lockup the less room for wear specially at 90% eventually it will wear enough that there is vertical play in the blade which can get very annoying. I prefer 30-40% because after some wear it settle in around 50% which is ideal
 
Yup, if it locks all the way without having worn in, you'll end up with a loose lock when it does wear in.
 
I know this is a zombie thread, but I felt that resurrecting it was probably better than starting a new one.

When you guys talk about the lock-up "settling in" after use, and aiming for a 50-60% lock-up after the lock has settled. I'm wondering if it'll go beyond "settling in" after more use. Or, do they reach a point where they stop?
 
Lockup means different things to different people, like 'tactical' the word means nothing without providing more context.

Some people gauge the percentage of lockup by how far across the tang the far edge of the lockbar is, others rate lockup by how close the edge of the lockbar is to the opposite frame.

mwally said:
I know this is a zombie thread, but I felt that resurrecting it was probably better than starting a new one.

When you guys talk about the lock-up "settling in" after use, and aiming for a 50-60% lock-up after the lock has settled. I'm wondering if it'll go beyond "settling in" after more use. Or, do they reach a point where they stop?
Click to expand...

It depends on the knife. The lock material, thickness, and angle of the lockface all come into play.

A hardened steel liner should wear much more slowly carburized titanium liner which should wear more slowly than a non carburized titanium liner. A thick titanium liner should wear more slowly than a thin one. A liner whose face is cut to match the face of the blade tang should wear more slowly than a knife where only a tiny corner of the edge of the lockbar interfaces with the blade tang.

A Chris Reeve Sebenza, with it's thick lock cut to perfectly interface with the blade tang and heat treated for wear resistance will last much longer than a $50 Chinese knife with a thin titanium liner lock that wasn't fit properly and was designed with cost-cutting in mind.

To answer your question, a properly designed liner or frame lock made from quality materials by people who care about what they are doing should settle in a little bit at first and then stay where it is for a very long time.
 
mwally said:
I know this is a zombie thread, but I felt that resurrecting it was probably better than starting a new one.

When you guys talk about the lock-up "settling in" after use, and aiming for a 50-60% lock-up after the lock has settled. I'm wondering if it'll go beyond "settling in" after more use. Or, do they reach a point where they stop?
Click to expand...


It's going to be different with every knife. It depends on a lot of factors, such as lock geometry, lockbar tension, and whether the lock face is treated or left bare, is the tang polished rather than a rough grind.

Galling occurs when Ti and metal interact. That's why the lockface wears down and the lockbar slides over. Little by little it's worn down. If the lockface is not carbidized than galling will always take place, and the lockface will continue to wear down. The lockbar might stay where it's settled, because it's travel is limited by the amount of tension that was put on it when created. That means, if you took the knife apart, how far would the lock travel with nothing hindering it. The person that makes it, has to bend it inward, initially.

That is where a knife develops lock rock or up and down play. The lockface continues to wear, but the lockbar does not travel any further. It than creates a gap between the surfaces. However, a lot of this can be avoided with proper geometry and other small steps. Polishing or coating the tang helps resist galling, as does carbidizing the lockface. I have a number of customs with no carbidizing that have been used extensively and have not moved off the 10% mark. That is mainly to do with perfect angles, or geometry.
 
Let jump in here with a question. Have you ever worn out a line or frame lock? If so, what knife was it and what kind of cutting were you doing with it?
 
MatthewSB said:
Lockup means different things to different people, like 'tactical' the word means nothing without providing more context.

Some people gauge the percentage of lockup by how far across the tang the far edge of the lockbar is, others rate lockup by how close the edge of the lockbar is to the opposite frame.
Click to expand...
Oh, that's good to know for the future if buying a used knife. Though, I always ask for pictures of the lock interface anyway. For the sake of this discussion, I gauge lockup by how far across the tang the far edge of the lockbar is.


MatthewSB said:
To answer your question, a properly designed liner or frame lock made from quality materials by people who care about what they are doing should settle in a little bit at first and then stay where it is for a very long time.
Click to expand...
That's the one line I was hoping to read.


GatorFlash1 said:
Let jump in here with a question. Have you ever worn out a line or frame lock? If so, what knife was it and what kind of cutting were you doing with it?
Click to expand...
No, but I haven't owned these knives for more than a few years. It just crossed my mind because I was thinking about how my Buck 110 from 1990 still locks up as sold as ever. It's seen a lot of use over the years, and is the knife responsible for starting my collection.

I've had a Seb for about 3 years. The lockup started out around 30%, and is now around 50%, and it seems to have stabilized here. I was just calculating that in 3 years it had changed by about 20%, and if it kept moving at that speed, I'd only have about 4 or 5 years left until it was at 80% (and nearing a point where it's not really useable). So I'm happy to hear that once the lock bar/tang interface has settled in, it sort of stabilizes. If I'm spending $300 or $400 on a knife, I'd hope it to be something I could carry for 25 years or more (just like my 110). The Seb has seen EDC use while I'm not at work, just basic cutting tasks, but has not been babied. But I've just purchased a used Strider SnG (w/ new lock geometry) to carry with me at work - career firefighter. This blade will certainly see some hard use. That's what sort of kick started all of the thoughts.
 
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GatorFlash1 said:
Let jump in here with a question. Have you ever worn out a line or frame lock? If so, what knife was it and what kind of cutting were you doing with it?
Click to expand...

Worn out? No. However, when I was in uniform, I used a liner lock so much that it started hanging up and was more difficult to close. The knife was a CRKT M16-02z. Not a very costly knife at all. I ended up dumping it in the trash and buying another. By that time, CRKT had changed blade steels so the replacement does not hold an edge like my first knife. I would gladly put up with the problems of my old knife to have the better steel.
 
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