Sticky lock = Good

[marthinus]

You can see from the videos that even with blade play a lock can still be very secure, very reliable and would require the entire lock to self-destruct in order to disengage.

Real interesting comments from Gavkoo on the folder of Kyle and what makers such as Bob Terzuola said about bladeplay being a thread for the specific market, yet there is nothing wrong with the design.

People presume that blade play is bad, but not for a reliable lock. I would venture and say that the Victorinox soldier will only fail if there is a catastrophic failure of nature, same as the Tri-Ad. Under static load, the soldier might even surprise the best of us.

Interesting thing on how durable a liner can be:

I hope this can be useful and educational to some. I know I went a bit of topic... from steel vs Ti, but you have to look at it as a whole in my opinion


One of the best ways I have seen to test a liner/framelock for any issues is to do the following (this was posted back in 2007):

Now to the test method I prefer. I recommend standing with the knife like you see me holding an Emerson liner lock here in the link below. But I also recommend you make sure the lock is getting behind the blade at least to the full thickness of the liner itself before doing this test if you are carrying a thinner liner locking folder. However even on the thicker liner locks and frame locks doing it with barely any lock touching the blade to make contact can possibly shear or ding in part of the lock making it either unsightly or worse so the lock should be at least 50% behind the locks on these thicker lock styles if you ask me.

I've shown this test to people that have carried liner locks for many years thinking they walked on water (as I once did also) only to see their faces when they pushed up on the spine of the blade while securing it just as I'm doing here in the link below only to see the lock slide off the ramp interface and allow the blade to close on their very trusted knife and sometimes surprisingly with very little pressure at all. If the lock even moves at all in this test its not good. You can candy coat it all you want but its not good. A surprising number of knives tested this way fail surprisingly easy. If your lock moves a little but doesn't fail on you from this test, well you have to decide then if its one you want to just use knowing this, or send it in to who made it for evaluation or if its just time to retire it. The reason I say this is simply because of this thought. Just because it moved a little and didn't defeat with the pressure you could muster with this test doesn't mean that a stronger man, or more pressure from an extreme use of the tip won't cause the blade to close on your fingers. Only you can decide on the action you take at this point. And in fact if it moves or defeats you can decide then and there if you want to continue on or mail it for repairs at that point for the professional to look at.

You should do this with your lockback and axis lock folders, and all other 'locking' folders too on occasion as well as check the lock mechanisms for debris, pocket lint, damage and if they have springs check their condition as well unless you can't see them of course. Small spots of corrosion, or thinned weak looking areas on springs should be dealt with by a qualified repair pesron promptly when it comes to securing your fingers..Injury from a sharp blade closing on fingers can lead to serious incapacitation for a lengthy time, numbness or loss of other sensitivity in the fingers, tendon damage and lots of blood loss. Don't risk it out of blind faith.

Hold your knife so if the lock defeats you won't get cut just as I'm doing here in the link. You owe it to your fingers to know not suspect or blindly trust that the knife was made correctly. You don't have to cock your wrist as I did here. I'm just doing that for my wife to get it in the shot easier. Hold it with both hands and using your strong hand with the blade resting on that index finger knuckle simply push up on the spine of your blade holding the body tight so its steady.

You can spine whack your knife if you just believe it causes no damage. But don't be surprised if when you find that it does in fact fail tests that the company doesn't cover the warranty due to the damage it caused to your folder on the inside. I'll leave your decision up to you when and if you cross that bridge.



STR

Umnumzaan design:

The ceramic ball lockup is supposed to look late, but in in reality is not.

Some of you wanted to see macr shots of the Umnumzaan after seeing the Sebenza shots in my other thread and,well, with such awesome feedback how could I resist.
So in no particular order here they are....let me know what you think.
Also, I was shooting outside and as luck would have it it started to rain and so you may see a drop or two of water in some of the shots. Luckily it's all stainless!

Added a little canned air to the perforated washer while trying to combat the rain drops and inadvertantly created a 'spinner'.

 

[marthinus]

Added from:
http://www.knife-expert.com/liners.txt


THE LINERLOCK -- RIGHT FROM THE SOURCE

Michael Walker's invention and development of the LinerlockTM

by Bernard Levine (c)1997 - for Knives Illustrated


The "Linerlock" knife is now so familiar that it is easy to

forget that both the knife and the name are relatively recent

inventions. Michael Walker made the first modern Linerlock in

1980, and he registered the name Linerlock as a trademark in

1989. Since the mid 1980s, dozens of hand knifemakers and factory

knife manufacturers have made locking liner type knives inspired

by Walker's designs, although very few of them fully understand

either the advantages or the limitations of this mechanism. The

best way to understand the Linerlock is to look back at how

Walker developed it.



THE EARLY DAYS

Mike Walker began to make knives early in 1980. One of his

first customers was a collector and dealer in Red River, New

Mexico, named Don Buchanan. Mike made ten fixed blade knives for

Buchanan. Don asked Mike for sheaths to go with these knives.

Mike made those leather scabbards reluctantly, then announced

that he hated making sheaths. So Don said, "Make folders."

Mike did. He made slip joints. He made lockbacks like the

factory folding hunters then on the market. He made mid-locks

with mechanisms copied from antique folders. But he was not

satisfied with any of these. Walker envisioned an improved folder

that would do away with what he saw as the many limitations of

conventional lockbacks.

First, he would design a knife that the user could open and

close safely and easily with one hand, without having to change

one's grip, or rotate the knife in one's hand.

Second, his new knife would do away with the sharp "back

square" of the conventional pocketknife blade. When a

conventional blade is closed, its back corner sticks out, and can

snag the user's clothing. In some folders the back square is

enclosed by extended bolsters, but this can compromise the shape

of the handle. Mike envisioned changing the basic geometry of the

folder, in order to eliminate the problem entirely.

Third, and most subtle, his knife would be self-adjusting

for wear. Other innovative folders of this period, notably the

Paul knife by Paul Poehlmann (patented 1976), were very strong

and very sleek, but they required careful adjustment of set

screws to keep their blades from working loose.



THE LOCKING LINER

Mike was familiar with the old locking liner design patented

by Watson & Chadwick in 1906 for Cattaraugus. Used first on

traditional folding hunters, this mechanism became standard on

electricians' pocketknives, and was also used on Cub Scout

knives. In this design, the liner projects above the handle, and

it is split lengthwise, alongside the pivot pin. The side of its

narrow tip engages the front edge of the tang when the locked

blade is open.

Mike noted that only a thin extension of the liner could be

used as the lock in the Watson & Chadwick design. This was

because most of the liner had to engage the pivot pin, in order

to hold the knife together against the tension of the backspring.

The result is that this type of lock is inherently weak.

Mike went back to first principles. He realized that if

spring tension and lock-up could be provided by a liner alone, he

would be able to dispense with the backspring entirely. With the

back spring gone, he could then have the end of the liner cut-out

engage the bottom end of the tang, making for a much stronger and

more positive lock. Indeed it would be nearly as strong as the

old Marble's Safety folder (patented in 1902), while dispensing

with that knife's long, awkward, and fragile fold-up extension

guard (the folded guard serves as that knife's lock when the

blade is opened).



STRONG AND SECURE

As it worked out, Mike had not anticipated just how strong

his new lock would be. About 1984 I helped to run side-by-side

destruction tests of all the types of locking folders available

at that time. Each test involved securing the handle of the knife

without blocking the movement of its blade or spring; then

sliding a one-foot pipe over the open blade (which was oriented

edge downward), to serve as a lever-arm; and finally hanging

weights from the free end of the pipe until the lock failed.

Name-brand conventional factory lockbacks failed at between

5 and 7 foot pounds (except for one that failed with just the

weight of the pipe). A Paul button-lock knife proved to be more

than twice as strong as the best of the conventional lockbacks.

But a Walker Linerlock was nearly four times as strong as the

lockbacks. What's more, when Walker's Locker did finally fail, it

failed in the open position. Instead of closing suddenly upon

failure, as all the other knives did, it seized up and became a

"fixed" blade.



SELF-ADJUSTMENT

This strength turned out to be a fringe benefit of Walker's

self-adjusting design. He based this design upon the simplest of

all mechanisms, the inclined plane, or wedge. The end of the tang

is slightly beveled. The end of the liner is not (although it can

be, as long as the angles do not match). Both parts must be hard.

When the blade is opened all the way, the liner passes the inner

edge of the tang, but it is stopped before it passes the outer

edge. The liner's leading edge bears on the beveled end of the

tang. If the pivot joint loosens over time, the point of

engagement of the lock-up moves further along the bevel, so it

continues to lock up tight.

In the destruction test, when we applied an extreme load to

the blade of Walker's Linerlock, the free end of the locking

liner moved all the way past the end of the tang, and wedged

itself between the blade and the fixed liner. Mike was later able

to disassemble and repair this test knife, and today it is

(almost) as good as new.

In his first Linerlocks (he was not calling them this yet),

Walker made the liners out of spring-tempered 440-C blade steel

(he did, and still does, his own heat treating). The lock-ups

were not yet the full width of the tang -- Michael changed this

after the destruction tests, to make his knives even stronger.

The thick 440-C liners of those early versions applied so

much spring pressure to the blades that no other mechanism was

required to retain the blades in the closed position. But when

Mike began to experiment with lighter gauge liners, he realized

that a separate element would be needed to perform this function,

which is performed by the backspring in conventional knives. In

1984 Mike began to incorporate a ball detent in the frames of his

Linerlocks, allowing the liner to be dedicated totally to lock-up

in the open position, while the ball detent held the folded blade

closed.



TITANIUM

These new lighter gauge liners were made out of titanium

alloy. Titanium has many features that make it especially

suitable for this application.

- Titanium has a high strength to weight ratio.

- Titanium has superb spring retention qualities, without the

necessity of any heat treatment. A titanium spring will recover

from a severe load that would permanently deform a steel spring

of the same cross-section.

- Titanium galls to other metals -- it seizes to them, rather than

slipping past them, when they are rubbed together under tension.

This makes titanium useless for moving parts, but ideal for parts

that are meant to seize, such as the end of a liner engaging the

end of the tang of a folding knife blade.

- Titanium can be electrolytically toned to a wide range of

attractive colors. Michael and Patricia Walker pioneered the

application of this technique to knives. In fact Patricia Walker

was the first artist to engrave and anodize titanium, both on her

husband's knives, and on her own jewelry and artwork.



ADVANTAGES AND LIMITATIONS

Walker's Linerlock mechanism is flexible and forgiving in

many ways. In the 1980s Mike would go to shows with a box full of

unfinished blades that he had ground freehand in all sorts of

 

[marthinus]

shapes. Customers would pick out ones they liked, and Mike would

then make knives around these blades, without any need for the

precise patterns that burden the makers of conventional lockbacks

and slipjoints.

However, one aspect of the Linerlock is not forgiving at

all. This is the bevel at the end of the tang, on which the end

of the locking liner bears. If this angle is too acute, the liner

will slip and the lock will fail. If the angle is too obtuse, the

liner will stick, and the blade will be difficult or impossible

to close.

Mike emphasizes that there is no single correct angle for

this bevel, as some writers have mistakenly claimed. Rather it

must be determined for each knife. The optimal angle is a

function of the blade and liner materials, of the spring tension

of the liner, and most important of all of the overall length of

the knife. The free end of the liner moves in an arc of a circle,

and the length of the knife determines the radius of this circle.



LINERLOCKS TODAY

Mike Walker rarely makes Linerlocks any more. He has

licensed the name, and various aspects of the mechanism

(including the patented safety latches recently developed jointly

by Walker and Ron Lake), to a few other makers and manufacturers.

On his own current knives he uses some of the dozens of other

locking mechanisms that he has invented over the years.

Mike is flattered that so many makers and manufacturers use

his invention, though he is disappointed that most of them fail

to grasp all the subtleties of the Linerlock mechanism. Because

of this, most of their knives lack the strength and smoothness of

Walker's own.

And Mike is angry at certain pompous Johnny-come-lately

makers who attempt to claim credit for his inventions and his

designs. One shameless maker is today receiving royalties for a

design that Walker created two years before that particular maker

assembled his first knife. But Mike never patented his original

mechanism or his early designs, so this sort of copying is now

water over the dam.

However Walker's trademark rights are another story. Mike

lets his lawyers deal with any makers or manufacturers who have

the temerity to use his "Linerlock" trademark without his formal

written permission.

 

[marthinus]

I see a lot of knives are starting to promote steel lock face inserts or carbidized lock faces to supposedly prevent your titanium lock from wearing away from meeting the steel of the blade.

Is this really a concern?

How long would a non protected titanium lock face last against steel?

Am I at risk of ruining my $1000 flipper that does not have a protected lock face by flipping it repeatedly?

Thanks!

If your knife is built right you won't have to worry about it. The lock will break in and shouldn't wear.

Some good work was done here to showcase the influence of lockbar cutout placement, however, it should be noted many knife makers etc have discussed this with engineers and in a knife the difference is negligible. If we were building massive structures then the case would be very different.

Hey guys,

i played around with Solid works to bring some numbers into the discussion weather the cutout inside the frame or outside the frame is stronger and to which degree.
The frame is titanium al6v4. The cutout is 7 mm long and 14 mm wide with 1,4 mm remaining material. The force applied ist 100 N. (SI units ftw )
As you can see is the stress (force/area) with the cutout on the inside two times higher compared to the cutout on the ouside. But even with this great amount of force applied is the stress very low so it is completly irrelevant in terms of construction.
"Streckgrenze" in the bottom right means yield strength which is the stress level above the material deforms non elastic.

The cutout inside:

the cutout on the ouside:

regards, Moritz

Added 2015

http://jgcustomknives.com/guthrie-tungsten-insert/


GTi LOCK:
The GTI lock stands for GUTHRIE TUNGSTEN INSERT. It features a Tungsten Carbide Insert fitted into the lock face of the R.I.L (Reeve Integral Lock) Tungsten Carbide is incredibly hard, achieving 90HRC on the Rockwell scale. This high hardness reduces lock wear greatly. A knife fitted with the GTI lock is guaranteed against any lock wear that will induce lock rock or vertical blade play.

LOCK TRANSITION:
This term refers to the maturing of the lock as wear takes place. The very small amount of lock wear (which now moves to the hardened blade) that could occur with the GTI lock has proved to be beneficial. It does not have the same detrimental effects as the lock bar wearing. Slope force is the sideways force the lock experiences when the blade is pressed against the lock. Increasing the incline on the blade lock face, increases Slope force. Increasing Slope force decreases reliability as the greater force wants to push out the lock bar, resulting in lock failure or lock slip. When a lock bar wears, it wears to the same incline it is being pressed against. In this case the incline of the blade. Slope force now increases and reliability decreases. With the GTI lock, the opposite effect happens. The Tungsten Carbide wears the blade to a shallower incline, which decreases Slope force, resulting in more reliability as time goes by.

Due to the nature of this exceptionally hard lock, it is not guaranteed against any spine whacking. Used as a normal cutting tool, this knife should never run out of lock life.



ROCKWELL COMPARISON:
Stainless Steel 25-34 HRC
Titanium 36 HRC
Hardened SS 58-62 HRC
Ceramic (Silicone Nitrate) 80 HRC
Tungsten Carbide 90 HRC

 

[marthinus]

Updated 2018, February.

Additional to the above based on Bob Terzuola’s and Michael Walker’s work Andre Thorburn has adapted a radius lockface, however slightly modifies it through manual adjustment to stop any lock stick from occurring. It is difficult to explain the process and I do not have permission from him to disclose additional information, but it proved once again for me, that geometry is key, above all else.

 

[Pilsner]

I think you may be talking to yourself here.

 

[colin.p]

Updated 2018, February.

Additional to the above based on Bob Terzuola’s and Michael Walker’s work Andre Thorburn has adapted a radius lockface, however slightly modifies it through manual adjustment to stop any lock stick from occurring. It is difficult to explain the process and I do not have permission from him to disclose additional information, but it proved once again for me, that geometry is key, above all else.

Thank You for posting this ( or reposting). Fascinating reading. I never fully appreciated the complexities of a simple locking folder, it was just something to use and hopefully work as intended.

 

[91bravo]

Those Russians look cold in that video. If I remember correctly, they name the Military as one of the toughest knives they've tested. Imagine that, a liner lock at that...

 

[Pilsner]

Those Russians look cold in that video. If I remember correctly, they name the Military as one of the toughest knives they've tested. Imagine that, a liner lock at that...

Jonny, I’ve found, unbelievably, a Carbon Fibre Military in 52100 available in the UK. Am sorely tempted as have never owned a military. Talk me into it!

 

[91bravo]

Jonny, I’ve found, unbelievably, a Carbon Fibre Military in 52100 available in the UK. Am sorely tempted as have never owned a military. Talk me into it!

The Military is a staple in Spyderco's line up. It hasn't been around for nearly 30 years for nothing. The Military has a liner lock that's done correctly. The 52100 is soooo easy peasy to sharpen up and gets stupid sharp in no time at all. The ergonomics is comfortable in a variety of grips and blade geometry out cuts many many other knives out there. If it's for a good deal, I would snatch it up! Don't let the tip down carry keep you away from all of its other amazing attributes!

 

[Pilsner]

The Military is a staple in Spyderco's line up. It hasn't been around for nearly 30 years for nothing. The Military has a liner lock that's done correctly. The 52100 is soooo easy peasy to sharpen up and gets stupid sharp in no time at all. The ergonomics is comfortable in a variety of grips and blade geometry out cuts many many other knives out there. If it's for a good deal, I would snatch it up! Don't let the tip down carry keep you away from all of its other amazing attributes!

Thanks mate, just the gentle push I needed...

 

[91bravo]

Thanks mate, just the gentle push I needed...

We're gonna need to see some pics too

 

[Pilsner]

We're gonna need to see some pics too

The deed is done. There will be photos

 

[James Y]

Cause CRK carburizes their lockfaces on the lockbar. Next time you have your Sebenza apart look at the bottom leading corner of the lockbar lockface and you’ll see a change in colouration there which is the hallmark of carburization.

Thanks, I knew they did something to the lockface.

Jim

 

[Someone1]

That is simply untrue. I have several excellent, reliable, well engineered steel liner lock knives. None have lock stick. I don’t know where you are getting your information but I would advise you to check your source.

I guess Michael Walker is a pretty unreliable source. In order to correct him, should you call him or should I?

 

[Pilsner]

I guess Michael Walker is a pretty unreliable source. In order to correct him, should you call him or should I?

Oh do give over. Michael Walker, God bless his soul, invented the liner lock. You are not talking to an ignoramus. However, the technology has moved on, as Mr Walker, being something of a scientist, would be the very first to accept. If you truly believe that a good liner lock is a lock that sticks, in 2018 soon to be 2019, then I pity you.

You can appeal to authority all you like, and it will meet with ‘meh’, from me at least. Unless you have used a really decently engineered liner lock, based on Mr Walker’s original invention, then you really don’t have much to say. If your view is that lock stick is good, then I am happy to refute that based on experience in the real world. We don’t all piss about flicking knives in front of the TV. I will give you the credit of using them too, but it seems to me that barring reading about the original, historic design of the liner lock, you really don’t know much about it.

 

[91bravo]

Liner locks weren’t designed to be sticky. Also a liner lock doesn’t have to be sticky to be effective.

 

[sharp_edge]

I have not posted the below in a long, long while and some links might be broken, but here goes for those interested in learning more on this lock.

My framelock post

This is a compilation of resources and discussion on angles, lock interface, steel vs. ti etc. that I have compiled over the years.

Here are some comments from a very well and respected maker on the forums that has tested numerous locks. I will not post his name as this was a private conversation and let’s keep it that way.

"I've done some steel inserts in mine. The wear rates are not far off from titanium to steel. Both wear very well. Heat anodizing helps to form a deeper near ceramic hardness on the titanium since heating it by a torch anodizes the ti from the inside out as opposed to using a DC current which is from the outside in or the outside layer only. That ceramic hard oxide layer wears pretty well against even the hardest blades. If it didn't people would have stopped using ti a long time ago.

The real factors as I see it is impact strength not wear resistance. In my own testing for Kershaw and other companies that sent me product to beat the snot out of on their behalf I found that the steel frame knives held up better to sudden shock impacts like spine and overstrike whacking as opposed to the softer ti which could indent easier and deeper scarring the surfaces more. So to me this is the key factor behind it but there is a draw back since steel is less forgiving than titanium. Ti tends to gall or stick to itself and dissimilar metals and this sticking effect has been seen forever by makers as a real benefit.

Not to sound bad but you can be off some on contact angle and get by with it by using ti since it can make up for your short fallings here whereas steel would just slide right off the contact. Steel will demand the contacts be spot on and if they are not well, you'll see locks sliding off the contact toward release easier than ti when the contact angle is not right.

I've used inserts of steel in a couple folders I did a while back. To me having to do them the way I did they were more trouble than they were worth. Most of my folders give me very little trouble as it is. However, I am low key and not selling what is being marketed as a 'hard use' knife either. We'll see how long this lasts but it could be the beginnings of a trend in the hard use category if people start testing them and find they hold up better. It will depend on the steel used. I really fail to see much benefit if the steel they are using is just 410 stainless at 45 Rockwell. Ti is 39 Rockwell or so and although softer by quite a bit technically it wears at such a slow rate that in normal use most folks are not going to notice any diff or benefit to this insert at all. It’s just the guys beating on them that will pick up on it probably.

Interest reading. This seems to also explain why (some) ti framelock folders with a steel lockbar insert tend to suffer lock slipping more easily than those without.