Torsion bars and ball detents

M

MarkN86

Joined
Sep 3, 2012
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So I was working with my Kershaw Compound today when "snap" went my torsion bar. My knife became a dangerous object whose blade would fall out if gravity allowed. Why can't Kershaw cut a detent hole for the ball? Is there a financial or patent issue? Seems like a lot more people would love it if more knives were able to be made manual, and it's also a fallback if that torsion bar breaks. I don't want to void my warranty by cutting one myself, now if I want to send my knife off for repair I'm out a knife.

Maybe it's been said, but why?
 
There may be a design/engineering conflict between the torsion bar and the ball detent (adding extra release pressure). I cannot say for sure. Some people convert theirs to manual with a detent, but I don't know of any knives that have both.

Kershaw will usually send you a torsion bar to replace yourself, if you don't want to send the knife in.
 
Blur, Needs Work, and Blackout are three that I know of that have the detent AND speedsafe. From what I understand the Compound bars, being a Chinese model, are not stocked and must be sent in. Kershaw is one of my favorite brands so I'm not bashing. I know I'm not the only one who thinks so, there are many just on this forum that would like the detents cut. Aside from just the internet, I'm sure people out in hardware stores and in the woods talk about their equipment and whether it works or doesn't work. The stupid thing is, this is a work knife, not a sit and flip repeatedly and admire knife.
 
well there are those who like the detent and those who dont. It is simply a matter of you cant please everyone. I might suggest buying another knife or maybe a couple of lower cost but effective blades so that if your favorite does come under some sort of issue you have a back up until you can get your kershaw back up and running. Another option is to tighten your pivot until a torsion bar can be sent out. It would flip but it will be safe. I do feel the need though to point out this this is nature of the beast with any assisted open or automatic knife. They are mechanical objects and a better way to look at it isnt if a spring or torsion bar will fail but when. It sucks I know but think about pretty much any other mechanical item you buy. Nearly none of them are user serviceable and in many cases problems with a car, blender, toaster or countless other items result in an inconvenience of some kind and you either wait for warranty or replace the item. If I were you I would consider a bearing flipper like the 0560. There is no spring operated mechanism to have fail and its just as fast.
 
I think the ZT 0350 has both a torsion bar and a detent. I would be happy to see all assisted openers include a detent hole.

After having 2 torsion bar failures in a couple weeks I lost trust in the mechanism. I gave my Avalanche to a friend and it has worked fine for him for at least 6 months.
 
I can't imagine a situation in which someone would specifically not want a detent hole drilled. In the models that have it, unless you look carefully you'd never know it was there.
 
Im not very educated on this, but if it had both, wouldnt they have to make the bar much weaker, because the bar with the kinetic energy from the detent could send the blade flying really hard, they could counter that by making everything tougher, but the price would probably go up, im probably wrong, but thats what i got
 
VENI VIDI VICI said:
Im not very educated on this, but if it had both, wouldnt they have to make the bar much weaker, because the bar with the kinetic energy from the detent could send the blade flying really hard, they could counter that by making everything tougher, but the price would probably go up, im probably wrong, but thats what i got
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They already have models with both and it works fine.
 
I recently contacted Kershaw and requested some extra torsion bars for the assisted Kershaws that I own. They sent me some replacements, no questions asked. I kept reading about these bars breaking so I got extras just in case mine do eventually break. I'd order a couple of extras and just repair the knife yourself. Jmo.
 
I called Friday afternoon and it turns out Kershaw has some of the Compound torsion bars in stock. I'm shocked, it's a Chinese model and they DO have the bars. They are sending one/some. I do love it that they will send them out to you. I still wish they had some kind of a backup method for keeping the blade in the closed position in case of failure.
 
MarkN86 said:
So I was working with my Kershaw Compound today when "snap" went my torsion bar. My knife became a dangerous object whose blade would fall out if gravity allowed. Why can't Kershaw cut a detent hole for the ball? Is there a financial or patent issue? Seems like a lot more people would love it if more knives were able to be made manual, and it's also a fallback if that torsion bar breaks. I don't want to void my warranty by cutting one myself, now if I want to send my knife off for repair I'm out a knife.

Maybe it's been said, but why?
Click to expand...

Mark,

What it comes down to is smooth action. The Speedsafe mechanism has what we call a "bias towards closure". After you push it shut about 70%, the torsion bar reverses on itself and wants to pull the knife closed (rather than helping to push it open). This is the reason that assisted opening knives are different than switchblades and, therefore, LEGAL. Switchblades use a spring that is under constant load when closed - if it weren't for the button or latch, the knife would open automatically. A Speedsafe knife requires you to push the knife open about 30% of the way before the torsion bar assists you and opens the blade the rest of the way.

So what's that point of all this, you ask? That "bias towards closure" creates a natural detent. We can always add a tradional ball detent to the knife by drilling another hole in the blade, but we have found that in many cases the action will be smoother without it. That's the reason that many Speedsafe knives don't have a detent hole.

On certain models we have chosen to add the detent hole, but at this stage it is not present on all of our Speedsafe knives.

- Jim
 
Just to throw my 0.02 out there.... I prefer the knives with the detent and the torsion bar. Yeah, it typically does require a little more force to get them started. But once they start, it seems they are quicker, more authoritative. I like that.
BUT, I like my Shallot, too. And my 301. I'm thinking the 301 would be amazing with a detent added.
 
MarkN86 said:
Blur, Needs Work, and Blackout are three that I know of that have the detent AND speedsafe.
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My blur doesn't have a detent . . right now all my speedsafe knives have broken springs but I still carry them safely without a detent. How loose do you guys keep your pivots that the blade just falls out?
 
fatherhudson said:
My blur doesn't have a detent . . right now all my speedsafe knives have broken springs but I still carry them safely without a detent. How loose do you guys keep your pivots that the blade just falls out?
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Reary? Pics or it didn't happen!
 
I have a carbon fiber blur. Maybe they took it out of the newer ones? I'm going to be fixing it soon hopefully, I'll take pics then.
 
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