liner lock lock up

[Omega]

i read in the how tos that the area on the blade where the lock hits should be ground at 10 degrees is that a pretty common practice and a good angle to use?


THX

Bill:evil

[grinddust]

Bill,I've heard some say they use 8*,some 10*and some up to 12*.I do mine 10* and it seems to work well.One concern I had about an angle any steeper was a chance the lock could skate off the blade and accidently close.Just my idea Bill.

[Omega]

ok 10 it is thank you


Bill:evil

[PeterAtwood]

I'm using 8 and getting good results, definitely an improvment over 7. I tried 9 and it seemed like a little too much, too easy to unlock but maybe it was just that particular piece. One thing I found out, it really pays to pick up a set of angle gauges. They were expensive but I am much more consistent since I got them and my angles are easily and accurately repeatable.

[Dave Kelly]

Bill,
Spend 16.95 or less and buy The Tactical Folding Knife by Bob Terzuola. I don't know how I would've made my first liner lock knife without this book. A whole lotta great basic and advanced information with pictures, jigs, tools, tips and diagrams. In it he recommends 8 1/2 for the lock. I second the angle gauges tip.

[Brett Schaller]

Also, click on Peter Atwood's link and get his framelock video. Lots of info applicable to locking liners as well as framelocks. Well worth the money.

Besides, he's got to pay for that new shop somehow!

[Kevin Wilkins]

8-9 degress with a radius

[Frank J Warner]

I guess here, as in politics, there is room for disagreement, and for being called a heretic and a wanker. But 10 degrees seems like an awfully steep shoulder and would work only if your lock is 1/2" long.

I've tried 7, 8, and 9 degrees and the tendency for the lock to slip (fail) is too great for my taste. Now, I like to make my locks really long, like 3/4 to 4/5 the length of the liner, and with a lock that long, I use an angle of no more than 6 degrees.

In the Terzoula book mentioned above there is a whole chapter on the geometry of the locking liner. That's all this question is about: Geometry. The optimum angle changes with the length of the lock and should be designed carefully with a decent CAD program or with pencil, paper and protractor.

-Frank J Warner

[grinddust]

Frank,so you're saying you calculate the angle based on the length of the spring which in a sense is the radius of a circle.Am I understanding this right?If I imagine a circle with a radius the length of the spring and the angle that the spring lines up on the circumference of the circle(which will actually be a little off center of the center point of the circle parrallel to the radius line) is the angle you need on the blade,right?This has really been the most confusing thing to figure on a knife to me yet.Thanks from Bill and I for any clarification on this process.

[Ray Rogers]

Well, I tried to keep my big mouth shut but just can't do it. Sorry.

I admit that what I am about to say is empirical. It was not worked out on a CAD system or even on a piece of paper, just experience. To me, the idea of using CAD to design a lock face would be with the aim of making the flat face of the lock bar sit flat against the ramp cut into the blade - CAD makes it easier to visualize the angles, arcs, and surfaces. That's all good but it works on the assumption that you want those two surfaces to meet flat - and I don't. I can see that if they did meet flat that a smaller angle, like 6 degrees, would likely be necessary to overcome any tendancy for the lock to disengage when closing pressure might be applied to the blade.

One problem is, you can plan and measure and CAD all you want but eventually you must bend that lock. Please remember here that I am talking in generalities and I'm not saying any of this is impossible - what I am saying is that most people aren't going to be able to bend that lock and maintain all that stuff that was planned with the CAD, especially with a tough titanium spring. Ya, you can work up jigs and ways to do it but I don't have any and I don't really need any.

My locks are also long, generally about 2.5" and my lock bar face is square when it is cut from the liner and it stays that way. The ramp on the blade is ground at about 10 degrees (I don't get too anal about it) and I like to adjust them so that when the blade is opened normally (not snapped open) the lock bar travels about half way across the lock face. Because of the square face on the lock bar only the leading edge of the bar contacts the lock face on the blade. There is probably some complex physics reason for it but this arrangement does not slip when back pressure is applied nearly as easily as a full face matching lock will (at least not at 10 degrees). And, it doesn't stick either if you get it right. You can turn this knife over and slam the back of the blade against the work bench and the blade will not close and the action does not get sloppy. What more than that can you ask of a pocket knife?

My main reason for getting in to this tirade is that Newbies already are scared to death that they will never get the lock right on their first folders (I know I was) and all that work will be wasted. Yes, there are many complex methods requiring great care, exact measurement, a jig of some kind, or heaven knows what kind of black magic and arcane knowledge but I feel that those methods don't really benefit a Newbie much. For the sake of argument, I'll even stipulate that some of those methods may well produce superior results to the methods I use but I think the important thing is to get that first knife or two built first and refine the skills and techniques as the understanding grows and the complexity can be absorbed.

Frankly though, I've not yet found a reason to do anything the hard way when it comes to making knives, except maybe the heat treating.....

[Frank J Warner]

Frank,so you're saying you calculate the angle based on the length of the spring which in a sense is the radius of a circle.

Yes but with a caveat. You want the lock face on the tang of the blade a degree or two steeper than the tangent of an arc which is the radius of the length of the lock.

The reason for this is so the lock will travel only so far and no further on the face of the tang. It also provides a little room for wear over the life of the knife.

I'm not about to second-guess Ray on this as I suspect he's forgotten more than I'll ever learn about knifemaking. But I've made several locking liner knives with steep angles (8-10 degrees) on the tang and was not satisfied with the way they locked up. I am much happier with a shallower angle, around 6 degrees.

-Frank J Warner

[grinddust]

Thanks Ray,Frank.You both have thrown new light on the subject.I'm glad I wasn't the only one scared to death about the lock.Thanks a bunch.

[Ray Rogers]

I want to make it clear that I am not trying to run down Frank's method. I'm sure it wiorks great. In fact, I'm sure there are many different ways to skin that cat and that most will give satisfactory results. Different strokes and all that....

Some people learn easily by reading instructions, some have to see a demonstration, and others learn best from verbal explanations. Here, all we have to work with is reading and writing. My post was typically long winded but the method described is pretty simple and when answering a Newbie's question, especially in writing, simple is better in my opinion....

[Don Robinson]

Frank, your explanation of the geometry involved was excellent, well said, and correct. I've never heard a better explanation of the lock relationship.

I agree with both you and Ray, though, that you don't want an exact match. If you have that condition, there is nothing left for wear, and the lock bar may eventually swing in its arc away from the blade notch.

Now for my tirade, Ray.

It's not enough for a craftsman to be able to do something. A good craftsman must also understand the "WHY" of it, and can analyze and learn from failures if he understands "why" it has to be a certain way.

I see two main purposes of forums like this. One is to teach "how" the other is to teach "why". IMHO

By the way, in my humble opinion, this idea of putting a "search button" in a signature line is counterproductive to the purpose of the forums.

There is very little added over time to the basics of knifemaking, so if we discourage questions, what would we have left to talk about?

I don't mean this to be antagonistic to anyone, you're all my friends. I'm simply stating my opinion. Please don't take offense anyone, just think about it.

[Osprey Guy]

Don-

The reason for the button should be clear...

There is a vast wealth of info available here...and so many newbies never even think to try looking for any of the answers (and there are typically so many different possible answers to any one question). The search feature was put in place to enable quick and easy access to all that info.

I love helping and participating...I know you do as well. But it takes time to respond to questions...you of all people should know that. Ever since you joined last year, how many times have you found yourself answering the same basic questions over and over and over. There are many tutorials available up top. There are in most cases, dozens or more answers to probably 95% of the questions that get asked. Are all the answers that have come before of no value?

You're not bothered at all when a newbie asks a question and clearly has made no previous attempt whatsoever to find even the beginnings of answer by devoting just a few minutes to reading? (yet another reason for the search button below, many newbies are unaware of the search feature).

The search is not meant to be used to the exclusion of questions. It should be used as an adjunct or at the very least, minimal preparation prior to asking a question.

The search button will stay with my signature thank you.


Dennis Greenbaum

Yeah Baby!