Strider/Hinderer Lock bar Cut out

[misterjuiceman]

I've heard claims that having the lock bar cut out on the outside of the titanium slab is more secure in terms of stress, versus having the lock bar cut out on the inside. Can anyone shed some insight on this?

 

[archieblue]

I reckon the idea is that the mass of the bar left behind is more in line with the tang of the blade so force is pressing on titanium rather than a cutout. It makes sense to me but I'm sure the benefit is minimal.

On the other hand you could think of the way CRK does it would have a little more angle to the bend of the lock bar. In this case, compression between the tang and lock bar would actually push the lock bar inward, strengthening the lockup. The angle of the tang would try and push the lock bar out either way, but a little more angle... and I mean a little would make some difference... again minimal. Both are good ideas and I don't have any preference.

 

[spidyman]

it has to do with the linerar stress involved. Having the cutout on the inside the bar tends to move out and over the outside of the handle when under significant sheer pressure which in a catastrophic case could cause the blade to slam closed. As opposed to having the cut out on the outside the the bar is more inclined to move toward the interior of the handle and collapse but still leave the bar in a position to stop the closing of the blade.

In terms of real world performance there is no significant benfit or advantage to one over the other.

 

[Thalestin]

it has to do with the linerar stress involved. Having the cutout on the inside the bar tends to move out and over the outside of the handle when under significant sheer pressure which in a catastrophic case could cause the blade to slam closed. As opposed to having the cut out on the outside the the bar is more inclined to move toward the interior of the handle and collapse but still leave the bar in a position to stop the closing of the blade.

In terms of real world performance there is no significant benfit or advantage to one over the other.

Basically, if your stressing the lock so much that it fails due to compression your screwed anyways

 

[orthogonal1]

Does anyone do freebody diagrams when thinking on these topics besides me?

 

[misterjuiceman]

I found this, but I'm not sure how true it is...

According to Mick Strider,
"If you think about the geometry of the knife, and the lock in particular, you will notice that the line of the stress caused by the lock interacting with the blade runs in a (mostly straight) line from the back of the blade down the lock and into the ti side handle.

If the cut was on the inside, the stress would run down the lock bar until it reached the cut, then it would transfer over to the other side of the lockbar…and cause the bar to flex and pop off the blade, rather than transfer the energy down into the rest of the handle."

 

[ExMachina]

If the cut was on the inside, the stress would run down the lock bar until it reached the cut, then it would transfer over to the other side of the lockbar…and cause the bar to flex and pop off the blade, rather than transfer the energy down into the rest of the handle."

this would generally be incorrect. any effect of the off-center line of compressional stress caused by an inside cutout is going to bow the liner inwards (so like archie said, the lockup will be enhanced)

my suspicion is that there are other, fabrication-related reasons for making the cutout on one side of the scale rather than on the other.

 

[archieblue]

If you think about bending a piece of material to the point of breaking, the inside bend of the material is compressed while the outside is pulled apart. Failure of the lock would be bending outward making the outside of the handle the inside of the bend. So in a case where material is removed from the outside not only is there a chink in the material on the outside, but no material. It would be like the material would be easier inclined to bend in the direction of the chink and zero mass to compress in the direction of preventing catastrophic failure.

Then you have the "pivot point." The lockbar is a spring, but the cutout is also a pivot point. It would make sense that having the pivot point farther toward the outside would actually have more resistance against pivoting outward.

On the other hand, CRK does one way on the Sebenza and the other on the Mnandi. At the same time, they have opted to put the cutout on the inside of the Umnumzaan. A company like CRK is no slouch in terms of making the best product out there and constantly making tweaks to better them. They also seem to put cost aside in order to make the best product out there. I would bet that the benefits/strength of having the cutout on the inside are more than having it on the outside.

 

[STR]

Tests don't prove one way is better over the other. In my own tests of production folders when I was doing that I saw nothing to indicate that the lock cut made one iota of a difference in how the lock behaved under stress. Some makers, Ken Onion being one, have done lock cuts on the inside on some models and on the outside on others. I think like many things in knife making its all based on theories that are imagined more than proved out.

One thing I have noticed myself for knives with lock grinds or lock cuts as we call them, on the outside is that the cut channel can at times catch the rim of the pocket and restrict movement of the knife upward to extract the folder for use. This is of course only noticed in tip up carry where the grind channel of the lock is relieved to bend it and put spring tension can actually grab the pocket or get pinched in the cut out rim on heavier pants and this is done by the pocket clip tension. One could argue that depending on the type of cut channel milled or ground out on the lock that this contributes to added pocket wear more convincingly than they could in how the inside or outside of the cut makes the lock behave under load.

STR

 

[misterjuiceman]

I should have figured not to believe Mick Strider...in the same FAQ, he mentions that blades on his knfie are off-center, because they perform better that way (it compensates for tolerances or something like that, he claims), and he mentions that he uses g-10 on one half of the sng/smf/pt because titanium flexes.

it seems like if Scott Cook would put the cutouts inside for the Lochsa, there must be no benefit to having them on the outside, because I'd imagine it's a hell of a lot easier to cut them out on the outside for a knife like that.

edit: this is off-topic but, I was thinking about it, and if somehow Scott Cook was able to bend a sheet of titanium that would explain how he is able to get the stop bar in there, and then the cuts on the inside would be no big deal.

 

[T.K.C.]

Hinderer Lock Bar Stabilizer Explained.
Per Rick Hinderer:

"I felt that I should write a post explaining the new feature on Striders framelocks, the Lockbar Stabilizer.......Of course as all of you have found out it is obviously a overtravel stop..in other words it prevents the accidental overtravel of the lockbar during closing of the knife...some of you have stated that sometimes repeated closings sometimes weakens the lockbar and thus the lockup is not as tight,well, I can visualize that,but actually the problem I wanted to correct concerning overtravel is the complete overspringing of the lockbar thereby rendering the knife useless...cant be done some say?...a little story of how I came up with it...I am firefighter as alot of you know...while working a accident scene I was using one of my Firetac's to cut the upholstery material around a seat post prior to using the jaws to cut the post...being that it was a good wreck, and adrenalin was running high,and the fact that we wear heavy glove when working a MVA,I pushed the lockbar way to hard thereby springing it,and of course the blade could no longer lock,not a good thing to happen, at the wrong time! I knew then I needed to do something about it...The other issue I wanted to address was the lockbar springing towards the back of the knife when gripping it...this is what is not so obvious in a improvement...the reason is that sometimes the movement in the lockbar is not really noticeable when using the knife under normal conditions...but when you use the knife really hard, and really grip it you WILL move the lockbar..this is because to make a framelock or linerlock for that matter you have to cut the long slot in the frame or liner to make the lockbar,it does not matter what size slot you cut you will still have material missing there...simple physics, suggests that you have a lever and it will move toward the back of the knife...guaranteed...now, what does this mean...1, whenever you have movement in a mechanism it is a chance for that mechanism to fail..2,extra movement in the lock to blade joint will wear the lockface quicker...3,when the blade is locked up on a framelock with the lockbar stabilizer there will be absolutely no movement in the lock....

So given all this is the improvement overkill? Extreme?.....when do we stop designing extreme use knives,as in ... is good enough the way it is?
Myself and Strider Knives design hard use knives gleaned from actual field experience,I didn't hear of this problem from anyone else in the field,I was in the field and experienced it!...Given the addition of the Lockbar Stabilizer Strider framelocks are even tougher and more hardcore than before..worth it? YOU BET!!"

 

[Kaizen1]

Hinderer Lock Bar Stabilizer Explained.
Per Rick Hinderer:

"I felt that I should write a post explaining the new feature on Striders framelocks, the Lockbar Stabilizer.......Of course as all of you have found out it is obviously a overtravel stop..in other words it prevents the accidental overtravel of the lockbar during closing of the knife...some of you have stated that sometimes repeated closings sometimes weakens the lockbar and thus the lockup is not as tight,well, I can visualize that,but actually the problem I wanted to correct concerning overtravel is the complete overspringing of the lockbar thereby rendering the knife useless...cant be done some say?...a little story of how I came up with it...I am firefighter as alot of you know...while working a accident scene I was using one of my Firetac's to cut the upholstery material around a seat post prior to using the jaws to cut the post...being that it was a good wreck, and adrenalin was running high,and the fact that we wear heavy glove when working a MVA,I pushed the lockbar way to hard thereby springing it,and of course the blade could no longer lock,not a good thing to happen, at the wrong time! I knew then I needed to do something about it...The other issue I wanted to address was the lockbar springing towards the back of the knife when gripping it...this is what is not so obvious in a improvement...the reason is that sometimes the movement in the lockbar is not really noticeable when using the knife under normal conditions...but when you use the knife really hard, and really grip it you WILL move the lockbar..this is because to make a framelock or linerlock for that matter you have to cut the long slot in the frame or liner to make the lockbar,it does not matter what size slot you cut you will still have material missing there...simple physics, suggests that you have a lever and it will move toward the back of the knife...guaranteed...now, what does this mean...1, whenever you have movement in a mechanism it is a chance for that mechanism to fail..2,extra movement in the lock to blade joint will wear the lockface quicker...3,when the blade is locked up on a framelock with the lockbar stabilizer there will be absolutely no movement in the lock....

So given all this is the improvement overkill? Extreme?.....when do we stop designing extreme use knives,as in ... is good enough the way it is?
Myself and Strider Knives design hard use knives gleaned from actual field experience,I didn't hear of this problem from anyone else in the field,I was in the field and experienced it!...Given the addition of the Lockbar Stabilizer Strider framelocks are even tougher and more hardcore than before..worth it? YOU BET!!"

Hey Suz,

I thought they were talking about the lock bar stabilizer when I first saw this thread too. They're actually talking about the cutout in the lock bar, why some framelocks have it on the inside of the frame vs the outside.