New twist on stop pins, I may be reinventing the wheel

Matt Shade

Matt Shade

Joined
Nov 24, 1999
Messages
4,981
I've been playing around with a few different designs for folders and was trying to come up with a way to have further adjustment for wear beyond the ramped shape of the tang where the liner engages.
What I came up with is a sliding spine thats made out of Ti. It only would work on larger knives. The idea is that the spine has a slot milled in it so that 2 hardened pins go through it and both handle slabs/liners and scales. These would be fixed like 2 stop pins with around 1/4" or more space between them.The back of the spacer is drilled and tapped with the hole parallel to the spacer. A hardened screw has to be fixed into the butt of the knife handle so that it can turn freely but not slide forward or back ( still trying to think of an easy way to do that one). Its screwed into the hole in the tail end of the spine and used to jack the spine forwards or backwards as needed. Enough room has to be left in the milled slot so that you can run the spine all the way forward until the liner doesn't enage at all, or only partially. Then you just use the screw to back the spine up a hair at a time until the liner is engaging as much of the tang as you want.The more threads per inch on the screw the easier it is to adjust.It also helps with the problem of everyone having a different opinion on how far across the liner should travel. Some want full engagement, while others want it to release more easily.
I don't know how it would work out, and it will probably be awhile before I even have the tools to make an effort at it. I'm not real sure that its a new idea either but I thought I'd toss it out here and see what you guys thought.

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I may not be the sharpest knife in the drawer... but I've got the sharpest knife in the room.
 
Wow Matt, sounds like you've had your thinking cap on. That is a very interesting idea and I'll be looking for some comments from the big guns about the feasibility. Seems like there must be a way to make it work. Probably the liner could be inset as a separate piece in a track of some sort but it would require some fancy milling.

Another benefit to this would be if the lock were cut a hair short- no need to hammer and stretch the lock.

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Peter Atwood

email: fountainman@hotmail.com
 
Peter:

Here's a drawing of one of my designs, called the "Man-O-War":

View


In the middle "cut-away" view you can see the modular lock and the two screws that hold it in place. This arrangement does allow for minor adjustment for take-up of wear. However, too much adjustment will push the detent ball out of alignment with the socket in the blade.

Also, remember that an eccentric stop pin will change the angle of the blade slightly when the knife is open and may also affect the closed position of the blade (i.e. alignment of the detent ball to the socket in the blade).

One of the reasons I prefer the "modular" lock is because it is much easier to replace than the entire liner (or blade) of a liner-lock or frame lock folder.

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Tom Anderson
Hand Crafted Knives


www.andersoncustomknives.com

[This message has been edited by Tom Anderson (edited 04-21-2001).]
 
Thats pretty cool Tom. I never thought of moving the lock bar. Is that set up as strong as a regular one peice liner?

I got my idea for the adjustable stop while looking at a Benchmade pinnacle. The spine is open and theres plenty of room for a piece to fit in the back without changing how the blade lays when its closed. Theres enough kick on the tang so that as long as the stop peice was straight on the edge inside the knife, and moved in a straight line, it would still meet up in the same manner as it does with the stop pin. The stop would just slide on two pins forwards towards the blade, or backwards towards the rear spacer as adjusted. I think the jack screw could be pulled off using a socket head torx or allen screw and welding a small washer to the base of the head so it can't slide back though the hole in the rear spacer.It might need a set screw through one of the scales to keep it from sliding forward when the knife is closed.
I wish I had some way of drawing a picture and posting it.I'm not sure if I'm explaining this very well or not.

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I may not be the sharpest knife in the drawer... but I've got the sharpest knife in the room.
 
Matt, did you ever make a knife using this idea for the adjustable stop pin assembly??
 
Seems like a lot of work when using a hardened stop pin or designing the knife so the stop pin is easily replaced would be simpler.
 
I always use a number drill bit for the stop pin and if adjustment is needed I can drill out the liners with the next size up number drill. Works for me.
 
Good geometry and materials stop most of the problems with lock movement.
I used to use a cam stop pin. I have stopped using it.
I have found by making the geometry right, using good materials for the lock bar and stop pin that most of the problems have disappeared.
Tom is right, if the cam adjustment pin has to much adjustment the detent in closed position of the blade become a problem. you have to adjust around this fact when you use such a system.

A movable or replaceable lock face (insert-tab) is a good idea. I just feel it is not necessary if the knife is built to tight tolerance and good materials are used.

With an insert tab (modular lock) it is nice to be able to re-adjust the lock bar. The problem is that it adds to the dilemma of more parts, and more adjustment systems can add to problems down the road if the cure (modular adjustable lock tab) moves after hard use. When lock strength is tested to over 1000 in pounds of pressure the failure rate of the lock bar goes up when adding adjustment parts.

When doing actual tests on locks that exceeds 1000 inch pounds I have found that : design of the lock bar axial engagement, tolerance of the pivot and other areas, lock cut on the back of the blade, and materials are the keys to lock longevity and strength.

This is not to say that every maker has their own way of building and designing knives. This is just what I have found from my tests.

Good luck
 
Hey Michael
Nope never made one. I don't have a mill or any of the equipment really necessary. I still would like to try one, just to do it but now that I have more experience with liner/frame locks I don't find the idea quite as necessary.



At the time I came up with that idea I had never done much with liner locks, but had read about other folks flicking them and all that. Then I got the pinnacle, and like most liner/frame locks the lock wore quickly for awhile, then settled in for the long haul.

I do have have knives that I've carried and beat the tar out of (the pinnacle is one) that are in need of some adjustment now. But thats been over a TON of use and they still lock up solid, the lock bar just goes all the way across. So I'd like to see something like this work I suppose. Something to make a liner lock that sees alot of hard use still something that gets passed down to the grandkids like the old slipjoints did.

I have to agree with Darrel that the right geometry and materials make all the difference in the world. But I like to over engineer things too, so I play around with ideas like this. I may try to make one sometime when sales are slow and I'm not busy with anything else.
 
Matt, what failed or loosened up on the Pinnacle to make the lock tab move so much?
I wonder if the stop pin was a cheaper steel?
I quit using stop pins because it just made sense that they would be more apt to wear quicker than a back spacer made out of heat treated 440c.
Plus I just prefer the look of a full back spacer.


Darrell, I sure am glad I dug this thread up!! :D
Haven't seen you post here in a while.
 
The pinnacle has a black coating of some sort on the stop pin, and is work down shiney where it makes contact. Thats probably good for a thousandth or two, and it appears to have flattened a little bit. Thats the trouble with a round pin.

Like you, I'm switching over to a backspacer made with hardened 440C. I've done one that way so far and really liked the results.
I'm glad you brought this up too, got me to thinking again. I may try something similar to that idea for fun sometime. I'll be sure and post results.
 
Matt,
Innovation is always fun and brings on new and exciting ideas.
Let us know how it goes with your idea.

Mike,
I lurk often. I am here watching and enjoying the posts. I try not to post until I see something that peaks my interest.

Glad to be hear as always.

BTW happy new year all on the forums.
 
Imho, the kiss principle is the way to go. The more part, the more that can go wrong (or the customer looses when he takes it apart).
Like has been said before, if it's built right and you allow for certain things, it'll last forever. The more you build of them, the better you understand those "certain things" :)
 
What I came up with is a sliding spine thats made out of Ti.
Click to expand...

Instead of a sliding spine...could you have a screw type stop pin that screws into the end of the spine? You could then screw it in, or back it out to adjust....The tang of the blade would rest against the 'head' of the screw....(kinda like this...ignore the quality, I just grabbed my little girls markers and doodled this up...)

screwpin1.jpg



I'm sure it would have to be specially hardened, and the threads might be a problem, they might get damaged from the stress of the blade striking the stop pin...

Just showing my ignorance....
 
That tells me two things..

1. I need to get out more....

2. Maybe I ain't as dumb as I think...

:D
 
Ok, ok, I get it.....:D

I should have known if I can think of it, it's not only possible, but it exists.....:footinmou :D

I was remembering how some of the machines that I ran,(In the furniture factory) used a similar screw set-up to make adjustments...
Some of those machines cycle thousands of times a day....so I thought...

I hope I wasn't stepping on any toes......
 
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