mechanism name ?

[G?rard Heutte]

Hello

I have a small question due to my poor English that is not my mother tongue?

Can anybody give me the name of the following mechanism for folding knife?



Thank you for your help.

[SVanderkolff]

Not sure which part you are asking about but the piece of metal at the back is a lock bar, I am not sure why the three holes in the lock bar. The one closest to the blade would be the pivot point but I am not familiar with the use of the other two. It would be easier to answer your question if you could be more specific what youare asking. Trying to get help in a foriegn language is a real challenge. Good Luck
Steve

[G?rard Heutte]

Originally Posted by SVanderkolff

Not sure which part you are asking about but the piece of metal at the back is a lock bar, I am not sure why the three holes in the lock bar. The one closest to the blade would be the pivot point but I am not familiar with the use of the other two. It would be easier to answer your question if you could be more specific what youare asking. Trying to get help in a foriegn language is a real challenge. Good Luck
Steve

Hi Steve,
The three holes are used to fix the spring between two liners. The part between the "notch" and the first hole is the spring that hold the blade in open position by creating a strength on the knife axis. There is no pivot for the spring. Moreover, it is only a spring not a lock bar. It works almost like a slip joint folder. This is not really a "lock" because the folder is just harder to close due to shape of the notch close to the axis.
I am looking for the name of this system, like "liner lock" or "lock back"...
I hope this clarifies.
Thank you for your answer.

[SVanderkolff]

Well I know it is not a liner lock I am pretty sure it is not a lock back so my guess would be it is a slip joint but I hope somebody comes by to confirm.
Steve

[G?rard Heutte]

Steve,
This system is close to the slip joint. But as far as I know, the part of the spring that is in contact with the blade is flat on a slip joint. There is no notch at the back of the blade. Here the design is slightly different. The notch modifies strongly the behaviour of the folder for closing...

[SVanderkolff]

Well I guess we will both have to wait and see what someone more knowledgable has to say.
Steve

[Don Robinson]

That is a modification of a slipjoint.

Looks like a good idea. Positive lockup, both opening and closing.

I've never seen anything like this. If you are the maker, please keep us updated.

Interesting. Thanks for showing us.

[Ray Rogers]

There is no existing name for that system, in my opinion. Technically, it is a slip joint because it functions like a slip joint (no lock, just pressure to release, pressure on the tang in both open and closed position). But, the notch is similar to what you would see on a lock back. So, a new name could be invented for it like the "Whizz Bang" system but a more usual name in English would be something like 'modified slip joint' or maybe a 'ramped joint'.

Anyway, it seems clever and I'm pretty sure it's original or close to it. I do have a question though, what happens when the blade is closed - how safe is it? Seems like closing the blade might require so much pressure that when it lets go the blade might close pretty quickly and possibly endanger some fingers....

[Don Robinson]

Ray, good point, but since the tang has a constant radius around it, it looks to me like it would slide all the way around under constant pressure and only snap closed at the last moment.

It would be safe until it reaches the notch under the tang. At that point the tip might be inside the frame or almost so.

Might be a problem though, when you need to open the blade. It would take lots of pressure to unlock it in the closed position.

I might put a flat on the bottom of the tang where the notch is, then it would open like a slipjoint.

Intriguing design, huh?

[SVanderkolff]

I would think though that the pressure needed to release the blade from the lock would be fairly hard. That wold be where the danger is.
Steve

[Ray Rogers]

Yes, it is an intriguing design. It would appear to be a touchy design to build just right by hand but you never know for sure until you try. I notice that the closed notch is not made to fit tightly on the spring's 'tooth' so opening would be much easier than closing.

A lot depends on the exact angles and fit of the tooth as to how easily the knife could be closed. As Steve points out, that's where the danger may lie. The rest of the equation will come from how strong the user's hand's may be as a weaker person might tend to wrap his hand around the handle to exert the necessary pressure and then get caught if the blade releases suddenly. But, this is all just conjecture since we do not now know if the release is sudden or smooth, if the blade will move quickly after release or if it will be more controllable, or much of anything else except that it seems like a cool idea. Hopefully, G?rard can provide some of these answers once he has finished a working knife.........

[Don Robinson]

OK, Gerard, you have our attention. Let's see one finished.

[G?rard Heutte]

Gents,
I will post this evening a drawing with such design showing open and closed position.
I will add some details and comments for the technical side.
This system is often used in France for many pocket knives (EDC).

[papi]

I think it's called L'aviolle system, used mostly in France, and for a long time (i'm talking about from Louis XIII long time)

I take no responsibility for errors in this info, i'm telling you just what i was told by a guy who makes them in our country

[G?rard Heutte]

Gents,

In France this system is used on a very popular pocket knife called "laguiole"...
This system name is "cran forc?" in french. This can translated as "forced notch"...

Here is a drawing of a knife in open and closed position :
knw_general.jpg


The adjustment of the knife in open position is made by removing steel on that point :
knw_open.jpg
I usually keep an excess of steel at this point. By removing steel, the point of the blade goes up (quickly !)


The adjustment of the knife in closed position is made by removing steel on these points :
knw_closed.jpg
By removing steel on the blade, the point goes outside the handle and the spring goes down.
By removing steel on the spring, the point enters in the handle.


To help the closing movement, a slightly flat part can be made as this :
knw_90.jpg
This creates a intermediate and stable position at 90?.


I hope this helps.