most reliable assisted opening mechanism?

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di$TOrTed

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Aug 9, 2013
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What do you all think would be the most reliable assisted opening mechanism?

A long time ago I broke a torsion bar in a Kershaw SpeedSafe knife; however it broke only a few weeks into me owning a knife so I think it was a fluke. I have years of use on my Blur and have had no issues, but I have extra torsion bars just in case. I was looking at the mechanisms on some of my other AO knives, and it seems to me that the beefiest are the ones that use a large leaf-style spring in the rear, parallel to the blade; such as on the CRKT Heiho and the Gerber Propel and Gerber Instant. Not too sure about the small coil springs inside SOGs and Benchmades; however I have heard more reports of the torsion bars in the Kershaws breaking than the coil springs used in a lot of knives. Seems to me like a torsion bar would last longer than a small spring but maybe not.

Your thoughts?
 
I have had my Kershaw jeep leak for over 10 years and it still kicks butt. I never had to replace it yet. but when it get's soaked it only opens half way. when it is fully dry it is back to be a fast open again.
 
Almost all of my Kershaw/ZT knives with AO have had the torsion bar break (not that I have too many) pretty quickly. Fortunately KAI's warranty is just as reliable and sends out replacements fast.
 
GronK said:
If you need absolute reliability nothing can beat a hole.
Click to expand...

What does this add to the OP's question? Are they making assisted-hole knives now?

As for the SpeedSafe knives, I've never broken a torsion bar, and my most carried knife, a Ti/ZDP Mini Cyclone came to me in April of 2007. KAI says they have tested the bars to 10,000 cycles, and I know I have well over that on my MC.

But as for anything man-made, there can and will be failures.
 
SPXTrader said:
What does this add to the OP's question? Are they making assisted-hole knives now?

As for the SpeedSafe knives, I've never broken a torsion bar, and my most carried knife, a Ti/ZDP Mini Cyclone came to me in April of 2007. KAI says they have tested the bars to 10,000 cycles, and I know I have well over that on my MC.

But as for anything man-made, there can and will be failures.
Click to expand...

Yeah, I broke the torsion bar for my Needs Work the first week I had it by basically opening and closing the blade slowly flexing it over and over. They sent me a new one and it's been solid for two years. Sometimes I zone out and flip it open and close it to, but it seems as long as one lets the blade open properly and not just fatigue the crap out of the spring they'll last and last.
 
I don't see how you could beat Benchmade's assists. The coil spring around the pivot is just like an auto. It's dang hard to break a coil spring. The Nitrous assists are well engineered too. I don't see how you are going to break two flat pieces of steel that are sprung on their vertical plane like an I-Beam.
 
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GronK said:
If you need absolute reliability nothing can beat a hole.
Click to expand...

I know. I'm just trying to get some thoughts on different assisted opening mechanisms because I haven't seen much discussion regarding pitting different designs together. Trust me, I'm all for having a good manual folder that can deploy just as quick as an AO.
 
I like assisted opening knives, yes I have broken torsion bars in Kershaw knives but they do last a long time. Also as previously stated the warranty is really good and will send out a replacement right away. So with a lifetime warranty knife it doesn't really matter if they break as long as you can get a replacement
 
di$TOrTed said:
I know. I'm just trying to get some thoughts on different assisted opening mechanisms because I haven't seen much discussion regarding pitting different designs together. Trust me, I'm all for having a good manual folder that can deploy just as quick as an AO.
Click to expand...

Didn't mean to sidetrack the thread. Just making a suggestion based on my own experiences. As for AO, I've cycled my ProTech Ciabatta for hours on end with no sign of spring problems. It uses the same coil spring as the full auto knives by ProTech. It snaps out with the same authority too and takes the same force to close. As for speed of deployment. . . . . . not so much. When I carry it I leave the safety lock engaged and in a belt pouch to protect the green jazz anodized aluminum body :o .
 
Some nice replies here :)

I just spend like an hour examining my knives (I gave in months ago to my knife addiction, i'm sure some of you can relate to this behavior) and I definitely think that the simplest AO knives I have are my CRKTs and Gerbers with the single, thick torsion bar in the rear. Seems to me that this would last a long time, but I am really curious if anyone has ever seen any of these designs break. I know it's not really an issue but I'm weird like that :) I like peace of mind. I don't feel as guilty flipping the manuals open all afternoon while watching tv as I do with the AOs.
 
Anyone have something to add over the last 2 years? Wanting an assisted but looking at most reliable mechanism. Already have had some nice Kershaws but wanting to try something different.
 
Keep in mind, generally speaking, Kershaw knives (while being a part of ZT) are “starter” EDC knives which are super affordable. Not to say cheaper knives will be less reliable I love some of my CRKT knives and they hold up to hard use, but we have to admit a $160- $300 ZT with AO torsion bar actions might be using a “stronger” or “better” designed and tested torsion bar design than a $40 knife? Just a thought. You get what you pay for in the knife world (speaking about production knives).
 
Droppoint85 said:
Keep in mind, generally speaking, Kershaw knives (while being a part of ZT) are “starter” EDC knives which are super affordable. Not to say cheaper knives will be less reliable I love some of my CRKT knives and they hold up to hard use, but we have to admit a $160- $300 ZT with AO torsion bar actions might be using a “stronger” or “better” designed and tested torsion bar design than a $40 knife? Just a thought. You get what you pay for in the knife world (speaking about production knives).
Click to expand...
Don't know if you realized but you restarted a thread that has been dormant for 6 years...
 
A good manual action. ;)

Seriously, the "more stuff to go wrong" argument is hard to ignore. I carried assisted actions a lot from the late 90s to mid-teens. Kershaw was my favorite. During that time, I only broke a few torsion bars. It was rare but it happened. The bigger issue for me was maintenance. They were more complicated, required extra steps, and seemed to need disassembly-level cleaning or tweaking more often.

I think one of the things driving assisted was the rarity or cost of good manual actions. Things have changed. Now you can get excellent manual actions on the cheap. I have a bunch of sub-$50 manual knives that open from a crisp detent with a satisfying snap. I have manual flippers and thumb-stud knives from Bestech, Kizer, and Civivi that put my old SpeedSafe knives to shame.
 
AO's always gave me the willies. Some subtle anxiety.
First one I bought, way back, was a Kershaw Whirlwind. Pretty neat, I (tentatively) thought.
Only $38 bucks brand new, a good size, USA made by a good company (Kershaw > Kai).
But still, the way it leapt open - could cause a nasty damn cut if it opened like that in
my pants pocket - not to mention that carry location is so close to those 'family jewels'.

😨

I decided it was pretty cool, but no way was I gonna carry it.

It was a pretty long time ago, but I then bought a Blur in S30V,
a SOG something or other, a couple of Benchmades, a Leek -
it was getting crazy, all these nice knives that I wouldn't carry.
Then it was the Hissatsyu - nice blade design but too fat and
heavy for my taste.
And then it happened, I bought a Buck Tempest off eBay,
the premium version in 154CM. When it arrived, I was both
amused and pleased to see the safety on the spine. Its location
and the way it operated was just too freaking clever.

Anyway, to finish this which is too long already, I guess
now I have maybe 25 or so AO's, all pretty much unused.
I don't intend to buy any more of them. And, in the end,
my favorite is = I don't have a favorite! I'd always have
my BM940, Millie in S110V, or PM2 in S39V.
Even the new Slim110 in S35v Every time!
 
unwisefool said:
Don't know if you realized but you restarted a thread that has been dormant for 6 years...
Click to expand...
LOL

And I just liked a post that's over 6 years old...

My leek and blur has been around for years now, no problem. I keep a few spare speedsafe parts around that I bummed off of kershaw for free. Their form online is easy to use and fast/painless AND free, I suggest using it. So far, not one speed safe died on me, and I've had...at least 20 assisted kershaws over the years of varying condition.
 
Don't the coil spring assists tend to lose the little tabs; that set the spring in place?
(Not that it makes the spring any less broken: of course!)
 
I've owned and still own a lot of assisted knives (mostly Kershaws/ZTs and some CRKTs).

None of the torsion bars in any of these knives ever broke and I can't imagine how one would. They are not under tension until the blade is deployed and are completely at rest when the blade is fully opened or closed.

However, I have encountered a few loose and "rattling" torsion bars, which I "fixed" w/a dab of vaseline to hold it in place.
 
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