Help with extreme detent.

AdamFuzzyballs

AdamFuzzyballs

Joined
Mar 16, 2015
Messages
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Hey y’all, I’ll post pics after work if needed but figured I’d go ahead and post to see what the brain trust works up. I ordered a Kizer Guru about two months ago- the model with thumb studs, NOT the flipper. Received it and under initial inspection it’s finished very well.

My issue is that sometimes the detent seems to “lock into place” when closed- to the point that it has torn skin off my thumb trying to open the blade with thumbstuds. Now, it is a small knife, so I thought maybe I was pressing the lock bar too hard, but even when I use two hands and grab it carefully not to put pressure, sometimes it is almost impossible to open.

The kicker is, when it doesn’t lock up, the detent is just about perfect. I can deploy it 50 times perfectly and then it’ll randomly become a vault. My only idea is that maybe the detent ball has a nick or other deformity that sometimes locks it up? Does it just need to be worn in, or is there some other explanation?

Thanks in advance for your help!
 
Filing in a detent ramp or flattening the ball itself, but if it works well most of the time I'd try other things first.

Have you disassembled it? I'd suspect a flaw in the detent hole (out of round, too big, burr, etc.) before a flaw in the ceramic ball. If you haven't, take it apart and see if there's anything unusual going on. Lube the detent track and the ball itself when you put it back together. With any luck, the problem will resolve itself.
 
OrangeBlueOrangeBlue said:
I'd suspect a flaw in the detent hole (out of round, too big, burr, etc.) before a flaw in the ceramic ball. If you haven't, take it apart and see if there's anything unusual going on. Lube the detent track and the ball itself when you put it back together. With any luck, the problem will resolve itself.
Click to expand...
This is most likely the problem. The ball is spinning when it works fine, when it doesn’t, you’re having a problem.
‘When you disassemble it, try to put some light oil over the ball, and try to spin it as much as you can.
 
POCEH KOCEB said:
This is most likely the problem. The ball is spinning when it works fine, when it doesn’t, you’re having a problem.
‘When you disassemble it, try to put some light oil over the ball, and try to spin it as much as you can.
Click to expand...
Detent balls that are pressed into a liner or lockbar don't spin.
 
POCEH KOCEB said:
This is most likely the problem. The ball is spinning when it works fine, when it doesn’t, you’re having a problem.
‘When you disassemble it, try to put some light oil over the ball, and try to spin it as much as you can.
Click to expand...

As WValtakis WValtakis said, the detent ball is pressed into place and doesn't move. But it is a very hard, very smooth, very round surface, so it doesn't add a lot of friction once it's out of the hole.

Detent strength is very dependent on the diameter of the detent ball hole, which dictates how much of the ball drops in - the more of the ball that's captured by the hole, the more force is required to get it out (stronger detent). Picture a basketball sitting on a champagne flute vs. a Solo cup vs. a industrial kettle; if the hole is too small, not enough of the ball drops in and the detent isn't strong, if the hole is too big, the ball will bottom out in the hole and will be really hard to get out. If your knife works well most of the time and randomly seizes, something is preventing the ball from exiting the hole, which I think is most likely a burr snagging the ball.
 
Most likely .... you are pushing too hard on the lock bar.

If that's not the issue, you can bend the lockbar out a little.
 
I personally wouldn’t purposefully weaken the lock bar. shinyedges shinyedges offered a good solution, if it doesn’t need to be worn in.
 
OrangeBlueOrangeBlue said:
As @WValtakis said, the detent ball is pressed into place and doesn't move
Click to expand...
Both of you are probably correct, I know in most cases they don’t move but they are balls tha rolls over the track.
I can think about Hinderer’s XM 18, where the ball is enclosed in the steel insert of the lock bar and I believe it rolls.
 
POCEH KOCEB said:
Both of you are probably correct, I know in most cases they don’t move but they are balls tha rolls over the track.
I can think about Hinderer’s XM 18, where the ball is enclosed in the steel insert of the lock bar and I believe it rolls.
Click to expand...
Nope...also pressed into the insert. The only rolling detent that I know of is Hoback's adjustable rolling detent system.
 
XM 18 detent ball is positioned on a post, it’s not pressed to the insert but I’ll go w your statement, I’m sure you got more experience, thanks :cool::thumbsup:
 
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