Question about detent..

Redwood25

Redwood25

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I'm curious about knife detent. I'm not a mechanical guy, really, but can see the moving parts in a knife. I understand about how the ball detent system works, in theory. What I'm curious about is how it can be that two separate, yet identical knives can have such a different level of detent. I've just noticed over time, and having 2 or 3 of the same model knives (both inexpensive, and pretty darned expensive), that often one is much more difficult to open. I'm hoping someone with more knowledge than I have can chime in a bit as to what causes this.

Thanks
 
In the case of a ball detent how far the ball is sticking out makes a huge difference. I suppose how deep and wide the corresponding hole was drilled does also. Also how the detention track has worn. And also if the ball itself has become flattened or not.

I adjusted the detent on my 0566 and just a little adjustment of the ball made a lot of difference in sloppy to tight detent.
 
Mass manufacturing doesn't allow exact same for anything

The detent ball can be layed into the lockbar at different depths. The lockbar tension can vary as they are not tuned exactly the same on each knife etc. Tolerance vary from knife to knife and manufacturer to manufacture. But that's the simple version.
 
Yep, could be one of, or a combination of multiple factors:
  1. How strong is the lockbar tension?
  2. How far does the detent ball protrude from the lockbar?
  3. How deep is the hole in the blade tang for the detent ball drilled?
  4. Are there any sharp edges on the rim the detent ball hole? (can sometimes make a detent super hard at first, but then it breaks in quite a bit later as repeated use smooths out the perimeter of the detent hole)
In my experience super hard detents seem to most often arise for me as a combination of 1 and 3. Lockbar tension is too strong for how deep the detent ball sinks into the hole. But on production knives it can be about any combination of all of the above.
 
Yup, I believe it...but how can I adjust the tension of my ZT 0456 so that it flips a bit easier? Adjust the pivot?
I am NOT aware of a pivot tool...if one exists, I'd buy it quickly...new or used..
 
The variation does make it feel magical when you have one that's perfect, though. My favorite Olamic Swish has an amazing balance of "stiff enough to flip hard" and "not so stiff that I can't middle-finger flick it with ease", for example.

You can often alter the level of detent force by carefully bending slightly more or less tension into the lockbar if you're motivated enough to take it apart and give it a try. It's not rocket appliances, to quote Ricky.
 
Sonnydaze said:
Yup, I believe it...but how can I adjust the tension of my ZT 0456 so that it flips a bit easier? Adjust the pivot?
I am NOT aware of a pivot tool...if one exists, I'd buy it quickly...new or used..
Click to expand...

The 0456 doesn't need a pivot tool, just torx drivers and you should be able to take it apart just fine.

Probably the only way to lessen the detent strength would be to take it apart and decrease the lockbar tension a bit. Gotta be careful when bending the lockbar, but the truth is I've done it on just tons of my knives and have yet to ruin one by doing so. If you bend it too far and there isn't enough lockbar pressure I've never encountered a problem bending them back.

But yeah. There are no guarantees and always be careful when messing with knives, etc, etc... ;)
 
You can lessen the tension without taking the knife apart. Putting tension back would require taking the blade out of the pivot.

If one likes a knife where the blade just shoots super fast then having some significant resistance before the blade starts to move is desirable.
Examples would be my three Ti Lite work knives. All three are surprisingly similar even though one is a six and the two fours are from different production lines because one is a CTS-XHP and the other is AUS-8. All three just fire very satisfactorily.

Unbending the bar just a hair and maybe smoothing the edge of the hole the ball seats into would make them easy to start to open but would likely lessen the lightning fast deployment.

Smoothing the edge of the hole is going to require taking the blade out.
 
Wowbagger said:
Smoothing the edge of the hole is going to require taking the blade out.
Click to expand...
Some photos

http://i.imgur.com/vZauYWw.jpg

http://i63.tinypic.com/14kcg21.jpg

http://i67.tinypic.com/hre9ms.jpg
Source for what they used: https://www.spyderco.com/forumII/viewtopic.php?t=81486
One used a diamond bit and the other some dremel tools.

A detent ramp can be a bit more difficult to get the right curvature... Could help on the drop if you don't like major catching on the drop.
https://www.bladeforums.com/attachments/img_3935-jpg.827919/

https://lh3.googleusercontent.com/-...AAAAAAAmJk/Cf9XV-OqymU/s640-Ic42/IMG_1524.JPG
 
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