Optimal position of the liner lock

[Alan0354]

Hi,

I want people that are experienced in working on liner lock folding knives to comment on this. Below is a picture of 3 knives with the liner lock grind to different position relative to the bottom of the blade.

Linelock position.jpg (37.34 KiB) Viewed 2552 times

1) The one on the right is the most common when one buys a new knife, ALL of them regardless of brand comes like this. The liner lock is on the far left side, some doesn't even go in far enough to flush with the side of the blade.

2) The middle one I grind so the liner is in the middle of the bottom of the blade.

3) The LEFT one I grind more to let the liner lock almost go all the way to the right side.

What is the reason why ALL the knives come looking like (1) on the right? I would think it is safer to have the liner at least like the one in the middle so the blade is LESS LIKELY TO FOLD BACK DURING USE.

Actually I would think the best is the one on the left that the liner is towards the right side. As you can see, even wearing out with time, the liner goes all the way to the right, it will be stopped by the metal plate(frame) on the right to prevent from going off the bottom of the blade. This should be the safest position in my book.

BUT before I make this conclusion, I want to hear from experienced knife people whether my conclusion is correct, also whether I am missing something that I should consider.

If I am right, it would be so easy for manufacturers to grind the liner to look like (3). Why not?

Please comment.

Thanks

[OLDE CUTLER]

Probably to allow for wear as the knife gets old might be one reason.

[Railsplitter]

I am not experienced in working on liner lock folding knives but here’s my take on it for whatever it’s worth.

The farther the liner sits to the right, the more likely it is to bend because of the angle between it and the blade tang.

[Reverand]

Also a liner lock that pushes further also keeps more tension on the blade when it is closed (and as it is closing). I have seen a strong liner lock push the blade into the opposite liner.

[Alan0354]

I am not experienced in working on liner lock folding knives but here’s my take on it for whatever it’s worth.

The farther the liner sits to the right, the more likely it is to bend because of the angle between it and the blade tang.

Thanks for the reply

You are talking about 2 or 3 deg difference, would it make that big a difference?

Particular if I grind so it is close to the middle one in the image, the difference should be very very tiny.

Thanks

[Alan0354]

Also a liner lock that pushes further also keeps more tension on the blade when it is closed (and as it is closing). I have seen a strong liner lock push the blade into the opposite liner.

Yes, I know what you mean. The liner has a round protrusion that fit into the hole on the blade at close position that keep the blade from flipping out accidentally.

I bend the liner further to the right also before installing onto the knife. That will put a lot more tension and harder to flip the blade out.

I always use a diamond round tip drill bit to flare the hole on the blade to round out the edge to make it easier for the the blade to slip out of the hole. It works beautifully.

[Alan0354]

Probably to allow for wear as the knife gets old might be one reason.

That should not be an issue as you can see the knife on the left side, it's all the way to the right liner. It will be stopped by the right liner from further moving to the right to slip out under the blade.

[Alan0354]

Still, my question is why ALL manufacturers grind it so it barely (if that at all) go under the bottom of the blade. I have seen at least 30% I bought that the liner is NOT completely under the blade when fully lock.

Are they sloppy, or they have a better reason? It is just too obvious for them to miss. I am an engineer myself(not expert on folding knives at all). But just common sense tells me the liner should go a little farther under the bottom of the blade even not all the way. Just like the knife in the middle of the picture. So it's not barely under, nor all the way to the other side.

Thanks

[Railsplitter]

Still, my question is why ALL manufacturers grind it so it barely (if that at all) go under the bottom of the blade. I have seen at least 30% I bought that the liner is NOT completely under the blade when fully lock.

Are they sloppy, or they have a better reason? It is just too obvious for them to miss. I am an engineer myself(not expert on folding knives at all). But just common sense tells me the liner should go a little farther under the bottom of the blade even not all the way. Just like the knife in the middle of the picture. So it's not barely under, nor all the way to the other side.

Thanks

You make some excellent points. I agree that the liner should make full contact with the blade. In my humble opinion, it’s defective if it doesn’t.

I don’t have an appropriate answer but the tangs are made with a slant at the contact point to prevent the liner from drifting to the right. I have seen hundreds of sale ads where an individual is selling a liner lock or a frame lock knife and they almost always include pictures like yours so potential buyers can see the percentage of lock up. For whatever reason, most buyers would not buy the knife on the left and many would not buy the knife in the middle.

Do you have a safe way to test the lock up on your knife on the left in your picture. Maybe put the blade in a vice and push on the handle to see if the lock easily fails? It might also create blade play because the slant on the tang might tend to push the liner to the left.
[/quote]

[OLDE CUTLER]

Probably to allow for wear as the knife gets old might be one reason.

That should not be an issue as you can see the knife on the left side, it's all the way to the right liner. It will be stopped by the right liner from further moving to the right to slip out under the blade.

Sorry I did not adequately explain it. I was referring to wear on the pivot pin, which from use will actually get a groove cut into it, especially if the joint is not kept oiled. I have had several of these liner lock knives apart where this was evident. The pivot pin had a groove in it which allows slack to develop in the lockup. As the pin wears the liner lock moves to the right as in your picture and takes up the slack to lock up tightly.

[Alan0354]

Probably to allow for wear as the knife gets old might be one reason.

That should not be an issue as you can see the knife on the left side, it's all the way to the right liner. It will be stopped by the right liner from further moving to the right to slip out under the blade.

Sorry I did not adequately explain it. I was referring to wear on the pivot pin, which from use will actually get a groove cut into it, especially if the joint is not kept oiled. I have had several of these liner lock knives apart where this was evident. The pivot pin had a groove in it which allows slack to develop in the lockup. As the pin wears the liner lock moves to the right as in your picture and takes up the slack to lock up tightly.

I think there is design problem that people missed. For STAINLESS STEEL, one has to be very careful to choose the composition of the stainless steel if two pieces are rubbing together.

If they choose the wrong kind, they literally rub each other away.

https://www.rg-group.com/what-is-stainl ... causes-it/

This is a serious problem in stainless steel semi auto handguns. It really depends on the designer knowing what two kind to use.

Heavy lubing really helps. I lube my guns with motor oil(thicker). It seems to work.

[Alan0354]

Anyone else?