Industry not listening?

[Bill1170]

A word about "notch sensitivity" in metals. All metals, in fact, all materials have this tendency – it is basic physics. However, the effect is largely neutralized by making the cutout with a smooth radius that is as large as practical. This is what you find on all reputable framelock knives.

It seems we would hear about it if failures of the lockbar were commonplace on framelocks. We don't, do we?

 

[MikeC]

Thank you Bill, that is what I was looking for. That makes sense from an physics and/or engineering stand point.

It is just that I have had knives with long shallow relief cuts where the actual thickness of the relief cut was pretty thick and yet it was easy to open and close. In fact the lock relief cut thickness is probably the most robust in the industry when measured with a caliper much thicker than the overwhelming super majority of Ti frame locks on the market. That left me to wonder why the extremes combine that with what I've been told about Titanium and it being notch sensitive and I think I have a valid question.

Yes, are striders and sebenza's made well, without doubt are they strong without doubt. I'm just a firm believer in over engineering or super engineering things. So if one manufacture has been able to have a long shallow relief cut whereby the relief cut is still pretty thick and the knife still opens, locks, unlocks and closes just as other ti frame locks with deep short relief cuts whereby the lock is left very thin compared to the rest of the handle? Striders are advertised as hard use and over built so why not do it up?

Bill, you maybe right if the radius is done correctly it is not problem but many relief cut outs I see are not done with a radius but are just rectangles are square if you will.

 

[mmarkh]

Here is a little something to chew on.

No lock will magically transform a folding knife into a fixed blade knife, not even a titanium framelock. Any lock will fail under sufficient load. By using the deeper relief cut, the engineers who are designing these safety devices are able to control 1) where the failure will occur, 2) what manner of failure will occur and 3) the amount of load required to cause the failure to occur. Would they really be making the lock "better" by changing the cutout to cause it to fail elsewhere, especially since that elsewhere may not be consistent? Is it better to know that the lock will fracture evenly at the relief cut under X number of pounds of load, or is it better to discover the lockface of the bar will shear first as it happens to you?

I'm not even going to get into the whole "cut with the edge, not with the spine" bit. I've carried and used slipjoints way to long to believe that locks are a necessary part of a folding knife.

Well said.:thumbup: I agree on all points.

 

[mmarkh]

Thank you Bill, that is what I was looking for. That makes sense from an physics and/or engineering stand point.

It is just that I have had knives with long shallow relief cuts where the actual thickness of the relief cut was pretty thick and yet it was easy to open and close. In fact the lock relief cut thickness is probably the most robust in the industry when measured with a caliper much thicker than the overwhelming super majority of Ti frame locks on the market. That left me to wonder why the extremes combine that with what I've been told about Titanium and it being notch sensitive and I think I have a valid question.

Yes, are striders and sebenza's made well, without doubt are they strong without doubt. I'm just a firm believer in over engineering or super engineering things. So if one manufacture has been able to have a long shallow relief cut whereby the relief cut is still pretty thick and the knife still opens, locks, unlocks and closes just as other ti frame locks with deep short relief cuts whereby the lock is left very thin compared to the rest of the handle? Striders are advertised as hard use and over built so why not do it up?

Bill, you maybe right if the radius is done correctly it is not problem but many relief cut outs I see are not done with a radius but are just rectangles are square if you will.

Who made this knife that you are talking about? The one with the thick relief cut.

 

[pvicenzi]

I for one, don't understand all the discusion concerning lock strenght. In 42 years of carying, using and sometimes abusing folding knives, I've broken a few blades, broken a few tips , bent a blade or two, and broken a few pivots. I however have never had a lock fail, that is with the exception of a lockback that got too much lint in the blade notch. Therefore, I feel that when discussing the strenght of folding knives, lock strenght is one of the last things to discuss.

 

[twid]

Really?........:jerkit:

I said that because he tends to think knife manufacturers make improvments on their models after they watch his videos. Keep jerk'n.

 

[jay2pointoh]

I said that because he tends to think knife manufacturers make improvments on their models after they watch his videos. Keep jerk'n.

This thread is not about your opinions on Youtube reviewers. There is another thread to express your views. It is in bad taste when you take any opportunity to attack someone you don't agree with in a place where it is not appropriate.

 

[Reeek]

Amen . . .

Here is a little something to chew on.

No lock will magically transform a folding knife into a fixed blade knife, not even a titanium framelock. Any lock will fail under sufficient load. By using the deeper relief cut, the engineers who are designing these safety devices are able to control 1) where the failure will occur, 2) what manner of failure will occur and 3) the amount of load required to cause the failure to occur. Would they really be making the lock "better" by changing the cutout to cause it to fail elsewhere, especially since that elsewhere may not be consistent? Is it better to know that the lock will fracture evenly at the relief cut under X number of pounds of load, or is it better to discover the lockface of the bar will shear first as it happens to you?

I'm not even going to get into the whole "cut with the edge, not with the spine" bit. I've carried and used slipjoints way to long to believe that locks are a necessary part of a folding knife.

 

[NDJeep]

The "industry's not listening"....???

Who have you actually talked to? Have you asked any makers why their designs are the way they are? Have you expressed your belief that they could/should do a better job with this issue?

Hmmmm.....

Seems that Chris Reeve and M. Strider to name a couple, have designed the lockbar cutout to be as thick as needed to be sufficiently strong...while sufficiently thin enough for ease of closure.

While I'm all for innovation and progress, I don't see the need for "improvement" with this specific issue...at least with the framelock knives I use.

 

[FlaMtnBkr]

So I have never really run across the term notch sensitivity. What is the titanium sensitive to when there is a notch cut in it? Cracking? Shearing? Bending? Or just a stress riser like any reduction in thickness will produce? Just wondering what is being eluded to with that term since the material properties of the titanium don't change.