Liner lock folder

S

Stickypoint

Joined
Apr 2, 2000
Messages
45
I've just started to make liner lock folders. I've made about 9 of them and all but 1 has the same problem. When I open the blade, the spring goes about 1/3 of the way across the lock face on the blade, but if I put pressure on the edge of the blade (like I'm cutting something) the spring moves farther across. (sometimes all the way across) I ground the lock face on the blade at 8 1/2 degrees. The lock face on the spring is ground square. There is no movement in the stop pin. The only thing I can think of is that the pivot pin has too much play in it. I drilled the pivot hole in the blade and did not ream it. Would the fact that I didn't ream it make enough of a difference to cause this ???

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When you first open the blade and engage the lock, is the face of the lock flush to the tang of the blade? Most times I use a 7 degree angle on my blade tang. I then use a hand file on the titanium to match the face of the tang of the blade.

You might want to put some dykem on the tang of the blade, open and close the knife several times and look at the pressure points on the blade tang.

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A.T.
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From what you are experiencing I can think of two possible causes. One could be where the pivot pin passes through the blade. The other could be where the pivot pin or pivot pin screws pass through the liner. These tolerences need to be tight. I ream the blade hole and liner holes to fit my pivot. I lap my blade pivot hole for smooth action. Wiggle you parts when the knife is partially assembled and see where you have the loose fit.
 
I have always used a reamer because it leaves a hole that is more round than a drill bit. I also drill/ream the liners so that the piviot pin goes through bought linners. The piviot pin will not cut into the linners like the screw threads will. I turn the piviot pin to fit very snug into the piviot hole, so that it takes some force to go into the hole. Making the blade stop concaved to match the stop pin creats more surface area for the blade to stop against.

The reason your lock is moving is because there is some flexing going on when you are cutting. Your blade piviot may be moving between the linners, blade may be moving on the piviot pin, blade may be moving on the stop pin.
If you start using a reamer the hole will be more round and this will give you more surface area against the piviot, less space for your blade to move when you put pressure on it. I also beleive that it is important to match the back of the blade against the stop pin, more surface area.
If you have time and what to, check out my photo page under folding knife. I put pictures on how I make my knives. It is a pictorial on the steps and setups I used to make a couple of knives. I was thinking about writing a book on it but don't have alot of time any more. Good luck in your knife making.

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Ray Murski
Photo page
http://albums.photopoint.com/j/AlbumList?u=935667&Auth=false
 
A light just went on !! I only ran the pivot pin through 1 liner and did not drill a real tight hole for the button head screw on the other side. When I tighten the screw down real tight I get very little movement. I'm going turn a longer pivot pin so it will make it through both liners. I ordered a reamer also.

I'll try matching the lock face angle on the spring to the blade also.
Thanks for the help...


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This is common is liner locks.
If the pivot is within .0002 (reamed)
and the stop pin is pressed in it will stop most of it.
The pivot also has to be tight in the liner.
I like to start with a pressed fit . The ti will mushroom a little and end up being a nice tight fit after you take it apart 30 times to finish it.

If you set your lock with very little engagment when you cut it , then slam the knife open 50 times it will ride over a bit after everything is set. This will help also.
Larger stop pins seem to help.

Also after using .07 thick 410 ss heat treated liner for a while I am much happier with the results. The ss dont give like ti does. The liners are stiff and the lock holds much better. The weight issue can be taken care of but skelotonizing the liners. This makes a much stronger knife IMHO.

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Web Site At www.darrelralph.com
MADD MAXX !

[This message has been edited by Darrel Ralph (edited 01-23-2001).]
 
I took 3 of the knives and lengthened the pivot pin by about 1/8" and then extended the pivot into the other liner. It made a world of difference. If I put alot of pressure on the blade, I can get the lock to go approx. 1/2 the way across the lock face on the blade. This is a great improvement. I'm still waiting on the reamer to come in, but I'm greatly encouraged. Thanks for all the help..

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