Anybody but me hate detents on pocket knives?

I just picked up several knives and all but one have detents. The force required to open them is quite hard and the subsequent ease of the blade arc makes opening less controllable, even dangerous. The knives are from Gerber and CRKT. The blasted ball bearing and hole technique makes it hard to remedy. I've tried hammering toothpicks and other things into the hole. Today I'm going to try epoxy. I shouldn't have to do this to make a brand new knife work well. UGH! /ubbthreads/images/graemlins/crazy.gif

What do you guys think?

-LT

what is a detent? is that where when closed it holds the blade in the case with a spring and ball and hole on the blade method? if so you can make it a bit easier by taking out the blade and chamfering the hole on the blade with a dremal and pointed tip polishing stone . I did mine like that and she is smoother on opening ..

Jeff,

Yes you've pretty much got the detent def. down. What kind of bit do you use for your dremal? I don't think any of mine will handle hardened steel.

-LT

Umh, w/o the detent, that blade is gonna open up on you. You need to get something nicer than a Gerber (who are now down the toilet after Fiskars brought them and is also copying Carson's M16)
Which CRKT do you have? My detents are insanely smooth

Yeah I agree you will need the detent also .. but if you use a small pointed stone on the dremel it will ease the abrupt hole that the ball fits into and make it easier to open..instead of a hole like this * | | * it will be more like this * \ / * but still serve it's purpose to keeping the blade in the closed position.. I just used a bit like this one .. standard silicon polishing bit with point .. Your right it ate the bit up pretty bad using it on the hardend steel but did the job..

ever had a knife open up in your pocket a little....then as you are trying to take it out have it open all the way and cut your leg VERY close to the important member?

I have.

I like detents /ubbthreads/images/graemlins/smile.gif

Detents are supposed to keep the blade closed in your pocket , think long and hard about tampering with them ! Reaching into your pocket and grabbing a handfull of blade hurts . Not being a smartass , look at trying some better quality/smoother actions .

Thanks guys. I appreciate the concern but I've been using pocket knives for years without the dreaded detent. They are a fairly recent phenomenon. Fortunately I've never had problems with blades opening when pulling them out to be used. The detents are simply a PC move to try and limit the liability of knife manufacturers.

GarageBoy,
Actually I picked up a few CRKTs: Ti M16, Starlight, and a Snap lock.

Jefff,
Picked up a diamond point and a tungsten carbide cutter the other day; both say they work on hardened steel. I may still try the JB Weld though.

-LT

Spyderco makes a variety of good knives that are held closed by spring tension instead of a detent. They open easily and smoothly. The Delica is a very popular model.

Lurker,

Actually I've got an ancient Delica (plastic clip) and it is one of the detentless knives to which I refer above. It's been a great knife but I like to swap around so I've got more than one EDC. It's just unfortunate that a lot of the new knives I think look nice have the detent from hell.

-LT

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Lunal_Tic said:
Thanks guys. I appreciate the concern but I've been using pocket knives for years without the dreaded detent. They are a fairly recent phenomenon. Fortunately I've never had problems with blades opening when pulling them out to be used. The detents are simply a PC move to try and limit the liability of knife manufacturers.


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LT, I'd definitely disagree with your interpretation here. When most of the world used slip joints or lockbacks, both of which are held closed via spring pressure, not detent was needed. But with the rise of liner locks, which provide no closing pressure whatsoever, some other way is needed of biasing the knife towards staying close. IMO, the detents aren't a PC move, they are a necessary feature, and only an irresponsible manufacturer would release a liner or framelock without one.

My biggest complaint about the detents is that they often seem like an afterthought. It many cases, the detents barely grab the blade at all, and there's almost no closing bias. That's my biggest complaint -- so many people have been cut by a knife opening in their pocket due to a faulty detent. Much more rarely, in my experience, is a detent that drops into its hole so abruptly that it becomes a pain to open. Given the choice of a bad detent, I'd rather take the kind that over-biases towards closure, instead of under-biases.

A proper detent should provide enough closing bias that it actually sucks the blade closed, once the blade tip gets within about 1/8" of closing. The liner's spring should "push" the ball down the detent track to cause this. The ball & detent should hold the blade in firmly, but not so firmly that you have to apply so much opening pressure that the thing flies open.

Joe

May not be a help, but the Sebenza has the nicest detent I've every worked with - very gentle, very very smooth, but enough to keep it safe. It's a tiny ceramic ball, and on my BG-42 blade, it's outstanding.

I think detents came along with thumb studs and the bronze phosphor washers. The actions are now so smooth and silky, and the studs so likely to catch, that the detents became attractive.

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Deanster said:
I think detents came along with thumb studs and the bronze phosphor washers. The actions are now so smooth and silky, and the studs so likely to catch, that the detents became attractive.

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To continue quibbling on this /ubbthreads/images/graemlins/smile.gif ... if your theory were correct, all knives with thumb studs/disks and slippery washers would have detents. However, knives with axis locks and lockbacks don't have detents. Why? Because axis locks and lockbacks already provide closing bias from the spring -- and, in fact, spring-based closing bias invariably works better than detents. Only liner locks and frame locks have detents, and they have detents whether or not they have thumb studs or slipper washers.

In short, there's no correlation between thumb studs and washers on the one hand, and detents on the other. The correlation is with closing bias. If the design has a "native" closing bias (slip joint, lockback, axis lock, arc lock, etc.), then there will not be a detent. If the design has no native closing bias (liner lock, compression lock, framelock), then there will always be a detent.

Joe

Actually, I'll respectfully quibble with your quibble. /ubbthreads/images/graemlins/grinser2.gif

In my observation, Axis locks and lockbacks often DO have detents - created by shaping the outer edge of the pivot area to create differential tension against the locking bar.

My Benchmade RST's are a great example - there's a fairly deep divot in the base of the blade where the Axis locking bar rests when closed, with a curved hump at the end of the divot.

To open, you need to apply enough pressure for the hump to push the locking bar back through about 75% of it's total travel, where it rides until the blade fully opens and locks- if that's not a detent, I don't know what is.

Older Spyderco, Gerber LST, and others show what happens when this is left circular - equal and smooth tension throughout the arc, until locking. By 'camming' the pivot, the behavior of the blade is altered.

The 'native closing bias' is nothing of the sort - you can make any of those systems have no such thing, simply by leaving the pivot circular, as was the norm for many years.

Slip joint and some of the more 'exotic' locking systems are a bit different story, but liner lock, frame lock, lockback, and axis lock all have a choice to use a detent or not, either through the ball-and-pit method, or by 'camming' the pivot.

While I'm the first to admit it's not conclusive, it sure seems to me that this feature has become vastly more common in the last decade or so, at least in parallel with, if not necessarily because of, the rise in thumb-stud and smooth-action features.

Ah, gotcha! In the knife universe, the only time I hear the word "detent" used is as part of a ball-and-detent system. Liner locks and their ilk have those. I don't think anyone uses the word "detent" to describe the geometric features on the tang that cause more camming action and closing bias, but if you include those, then you could be right, or at least have part of the explanation. On the other hand, for as many years as I remember, it's always been considered bad design to have a lockback that doesn't provide closing bias, although you may be right that the standard has increased (I'm motivated enough to check my old lockbacks!).

Joe

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Jefff,
Picked up a diamond point and a tungsten carbide cutter the other day; both say they work on hardened steel. I may still try the JB Weld though.



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If you do decide to try using the dremal .. keep in mind it wont take much to improve the action on the detent hole.. just smooth them out a bit so that it is not a pain to open .. too much of a chamfer or angle will let the blade have play in the closed position .. it will be a touch it and check type of operation with the dremal .. hope you get what ya want out of it ..

Hi Joe,

No trouble with you disagreeing, you're entitled. I think however that you'd be hard pressed to accidentally open a tip-down folder when drawing, tip-up. . .maybe, depending on protrusions but most folders seem to be tip-down these days. Of course I'm one of the oddballs that like tip-up designs. /ubbthreads/images/graemlins/grin.gif

Perhaps if the ball was bigger and the hole was chamfered it would work better. All I know is the most recent batch of knives I've gotten are detent hell and I will have to do something about it to make them serviceable.

-LT

With tip down stuff it isnt a big issue when clipped , however it can be a nasty surprise if you go clipless . I ended up with a pocketfull of blood that way .

The ball & detent serves two functions on a well-designed liner-lock. Other than providing tension on the closed blade (where the ball goes into the detent), it serves as a bearing surface on which the blade tang slides open, keeping the liner from touching the blade across a large and ever-changing area. Without the ball, the blade would not open properly or smoothly. Look at the tang, and you'll see a circular path on which the ball rolls. That ball is what keeps the liner from hitting your blade.

The smoother the ball and the smoother the tang, the less obtrusive the action. And in most instances, rough opening is due to a poorly finished or poorly designed ramp on the tang, where it first contacts the liner. On Benchmade linerlocks, or any well-done quality Walker-type liner, there's a very smooth opening action. The amount of transverse pressure the liner exerts on the blade varies by knife.

Try lubricating the ball and tang with Militec, and heating with a hair dryer until you can't touch the steel. Remove the excess, and do it again.

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Lunal_Tic said:
Hi Joe,

No trouble with you disagreeing, you're entitled. I think however that you'd be hard pressed to accidentally open a tip-down folder when drawing, tip-up. . .maybe,

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Ya, I agree. I don't think the main concern is on the draw, though, it's that if the knife jostles around, it can open up by itself. With tip down, when you sit or bend over, the tip of the opened blade could bite you. There's so many stories of liner and frame locks -- with detents -- opening up and biting people, that I don't feel this is a completely rare occurrence. I know it hasn't happened to you, but it only takes once.

I do agree with you that the ball shouldn't fall into the detent so abruptly that the thing is hard to open, and then the blade flies open once it's cleared. That's just bad execution. Aside from my zillion other complaints about liner locks, the frequent bad execution on the ball and detent is yet another.

Joe