Lock up % vs. Detent strength

I never said that bending the lock bar will not help with detent.

Detent, when done PROPERLY from the factory or the custom maker should already have:

A: the right size ball/hole.
B: the right amount of tension.

This achieves whatever the desired detent is.

Answer me this. How much should you bend the lock bar when you take apart a ZT? There is no right answer, you will have to experiment.
I would imagine the bar is Ti, not the easiest of materials to mess around with bending. (I have been there)

It's a new knife. Just send it back and let KAI's exceptional service do whatever they do to give you a good detent.
 
Given the varying detent strengths on most liner/framelocks I am pretty confident that the lockbars are bent by hand in the factory. So not every model XXXX is going to have the same lock bar pressure NIB. So there really is no "right amount of bend" in the lock bar. I have tuned many liner/framelocks, if you are at least semi competent in mechanical dealings the knife will not spontaneously combust.
 
JR88FAN said:
I never said that bending the lock bar will not help with detent.

Detent, when done PROPERLY from the factory or the custom maker should already have:

A: the right size ball/hole.
B: the right amount of tension.

This achieves whatever the desired detent is.

Answer me this. How much should you bend the lock bar when you take apart a ZT? There is no right answer, you will have to experiment.
I would imagine the bar is Ti, not the easiest of materials to mess around with bending. (I have been there)

It's a new knife. Just send it back and let KAI's exceptional service do whatever they do to give you a good detent.
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You bend in small increments. That is what you do whan setting a detent. You say there is no set answer and you are right as it is done by feel not math. When adjusting a lock i usually measure the existing distance, estimate the existing pressure and make less than a mm increment until i am pleased with the action. Which again is exactly what most if not all factories would do and will do if he sends it back.

Test it yourself. Take any knife you have and disassemble it and measure the gap between the lockbar face and the scale its bent out from. Then send that knife in for a weak detent. If the company will even consider your request. When you get it back measure that distance again and take note of the resisance as the blade moves. All locks are set by hand. If you dont set it strong enough in the first place to fully engage do you bend it a bit more or would you do regrind a new blade with a longer lockface? Im gonna go with door number one bob.
 
kniferbro said:
Given the varying detent strengths on most liner/framelocks I am pretty confident that the lockbars are bent by hand in the factory. So not every model XXXX is going to have the same lock bar pressure NIB. So there really is no "right amount of bend" in the lock bar. I have tuned many liner/framelocks, if you are at least semi competent in mechanical dealings the knife will not spontaneously combust.
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Thank you.
 
For the last damn time!!!!

I don't disagree with you Purple, it's just not the way a detent SHOULD be set, it can be tweaked that way though for sure.
Kit Carson published some great work on how he puts together a folder, and he does not set detent by bending lock bars, I can assure that neither does ZT. The tolerances are all set in machining.

This was a mistake at the factory with the ball/hole in relation to the lock bar.

That is all I am saying. The BEST way to fix it is the right way, but yes, you can just try to mess with the lock bar....

Yes, I have a fragile heart....just don't call me 'Mom'.....
 
Listen we will have to agree to disagree. I work on knives all the time. And one saying always holds true in this world which is there is always more than one way to skin a cat. Kit carson writings are not the only writings and while he contributed a lot to this hobby there are many who did things differently than he did.

Is is the last time i will say this before i just move on and people cam decide for themselves. A strong detent is a combination of numerous things. Even when the detent hole is exactly the right size, and the ball is set into the lockbar at the proper depth and the handle is aligned so that the ball will seat properly, NONE of it will matter if the lockbar is not properly set. and if you dont set it properly the first time you dont start swapping parts or making a new knif or expanding holes. You make a minor adjustment to your setting. Your "right" way would only be correct if the hole or ball was grossly out of spec which most time this is not the case. And you cant assure me that zt doesnt adjust lockbars to correct detentw because they have discussed them doing just that when everyone was complaining about the detents in there 0560 a few years back. Please dont ask me to dig it up as you can find the info if you look. I havr been pimping knives for years man and i have more than a passing interest in how these things are done. The right way is whatever gets the desired results with the least risk to the product and enlarging detent holes or replacing detent balls is a last resort.

Dont forget you were the one who came into this theead saying my advice was the improper way to do things. You say you are not disagreeing but in fact whan you say its not the right way you are saying its wrong by default. And so far you havent explained how YOU would go about fixing it besides sending it in. All im asking is that if you know better than countless makers and people working repairs i ask that you show your work and provide more than "because i said so". And "i read how kit carson sets detents." You may have read how he initially sets them up but what did you read about correcting them?
 
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You set the lock bar first, then you make your detent ball/hole to fit. The ball/hole dimensions will dictate detent as they work with the lock bar tension.

The proper way to correct the problem is to re-do the entire lock side, but the quick way is to bend the lock bar.

That's the last of me in this thread.
 
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Zt knows what they are doing and how to properly adjust/fix their products...I would sent it back or if possible take it where you bought it and swap it out...

If you send it in, I bet you will have it back in less then 10 days
 
JR88FAN said:
You set the lock bar first, then you make your detent ball/hole to fit. The ball/hole dimensions will dictate detent as they work with the lock bar tension.

That's the last of me in this thread.
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Is it possible the detent hole is to big?
 
vinnier6 said:
Is it possible the detent hole is to big?
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If the detent hole is too big nine times out of ten there will be forward and reverse play in the closed position because the hole would be larger than the diameter of the ball being used. Here is a thread where thomas and jim from zt explain detents and the 3 main factors effecting them when I asked about them before I did these kinds of adjustments. Most of my pimping was cosmetic until a year or two ago.

http://www.bladeforums.com/forums/s...0-detent-Can-a-weaker-one-be-made-more-strong

JR88FAN said:
You set the lock bar first, then you make your detent ball/hole to fit. The ball/hole dimensions will dictate detent as they work with the lock bar tension.

The proper way to correct the problem is to re-do the entire lock side, but the quick way is to bend the lock bar.

That's the last of me in this thread.
Click to expand...

Maybe Kit "installed" detents that way. But thats not how it is always done Many makers these days know how they like to install detents based on the design. They have a prefered ball size, prefered depth and prefered method of peening the ball into the lockbar if not simply pressure fit. And usually you would install the detent ball before bending the lockbar but after cutting the lockbar cutout because its easier to drill into a lockbar when it is sitting flat and not kicking upward. After installing the detent ball you do a test fit assembly with your ground but un heat treated blade. You bend the lockbar using lockface engagement and resistance during blade rotation as a starting point. This many times WONT be your final adjustment. You then proceed to move the blade back and forth opening and closing it. This creates a minor impression in the softer steel and shows you your detent track. This will allow you to know precisely where you should drill that detent hole. Then you drill the hole before treating as drilling into heat treated steel destroys tooling and is much harder to do. During this whole process you are able to check your depth, and position of detent and how far the ball seats into the blade. If all these things are within spec and you still arent getting a good enough positive detention you adjust the lockbar. This process is for a hand made custom knife.

If you are doing production knives usually you are trusting the CNC program to cut and drill each part within spec. And just like Jim states in that other thread detents will vary due to minor variances in tolerances. But there isnt a production company on earth that is taking a full titanium lock side and tossing it in the trash and giving you a brand new lock side simply because a customer thinks the detent is weak. They arent ripping out their standard size balls and putting in bigger ones. And there isnt a guy sitting on a bench with a drill or hand reamer enlarging holes in heat treated M390 or Elmax blades. They adjust the lockbar because it is one of the quickest, easiest and most effective way of delivering the desired results. And again, it IS THE WAY they correct all weak or too strong detents if there is no sign that the knife was improperly made.
 
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PURPLEDC said:
I think you should contact the majority of modern production facilities and them know they have been correcting weak detents all wrong for years. Kai, begg knives all have simply tweaked the lockbar on knives I have sent in for such issues. I know for a fact strider as well as many others do this too. Poor seating due to lint isn't the issue on a new knife out of the box. All lock bars are set by hand and all they do for poor retention is adjust the tension. Even with a perfectly executed detent it won't hold if the bar is set too weak. Do you really think instead of applying a tiny bit more pressure that they rip parts out to compensate? They don't remove or replace the ball, or enlarge the hole. That causes too many problems. What you are suggesting is that they turn the planet to screw in a light bulb.
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Sorry I got you upset.

If the lockbar tension is strong enough to hold the knife open, the reason it won't hold it closed is misallignment or mismatched size of ball/hole, not the force of the lock bar. In the old days before Walker invented the ball detent, the knife was held closed by pivot tension, or a slipjoint type spring.

Either way, if it is brand new, it should not have been sent out with a bad detent and should be returned as defective to the dealer.

I was told by a knife company ( can't remember which one) that lint is the most common reason for a ball detent to stop working good, particularly if the knife has been over lubricated.
 
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brownshoe said:
Sorry I got you upset.

If the lockbar tension is strong enough to hold the knife open, the reason it won't hold it closed is misallignment or mismatched size of ball/hole, not the force of the lock bar. In the old days before Walker invented the ball detent, the knife was held closed by pivot tension, or a slipjoint type spring.

I was told by a knife company ( can't remember which one) that lint is the most common reason for a ball detent to stop working good, particularly if the knife has been over lubricated.
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You didnt upset me. I just disagree with you and jr88fan. I think you guys are missing one huge factor in all of this which is the type of knife being discussed which is a flipper riding on bearings. In this case the detent plays a larger roll than just keeping a knife blade in the closed position. In a bearing flipper it is widely accepted that a detent in most cases be strong enough that no wrist movement be needed to open the knife. It is designed to allow energy to be stored and once that detent is overcome there will be enough of that stored energy to fully deploy the blade. A weaker detent may be perfectly acceptable for the purposes of a traditional folder with a thumbstud. But my answer was taking into account the very knife the op was speaking of. And with that being the case the lockbar keeping the blade open without lock rock is only one of the desired traits. And even with perfect alignment and seating if there is not sufficient pressure the knife wont open as intended. And just as i said before many times if sent back they will tweak the bar and only explore other options if tweaking the lock does not yield the desired results. Now if the look at the knife and see the ball isnt even contacting the hole in the blade? Sure they may try to adjust for that. But usually this is not he case.
 
Blade and Flame said:
If the detent ball is sitting shallowly in the detent hole of the blade, detent strength can be increased by making a larger hole. It's an easy tweak to do with a ball nose end mill and drill, but of course it probably voids your warranty.
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I actually did this with a 0550. Not for the novice so to speak and the hole was only oversized about .003-.004". The bit almost fit prior to drilling. It's a delicate balance doing this. The hole must not be oversized enough for there to be closed play or enough so that the lockbar contacts the blade. Fortunately for me, it worked exactly how I wanted it to.
 
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This is great convo.

Only thing I know is I hear some about the detents on the 560/561 being all over the place. I got lucky and got a couple that are perfect and work equally well by flipper or stud.

Were I you, Major Harry, I would not attempt to drill the blade unless you are a machinist with proper tools and know exactly what you are doing. It will void the warranty. Attempt what PurpleDC is saying first....see if adding slightly more push to the lockbar will fix the problem. You can take your time and get the feel of the bar and probably be able to perform a slight tweak of the bend with a little patience. I would try it and I'm no mechanic.

If not or you don't wish to attempt that either, send the knife back for factory adjustment. If it is that weak you'll be glad once it's properly fixed.
 
From the newb's bench:

I 'adjusted' the lock bar's tension slowly and carefully with the following results:

1. First attempt at bending the lock bar yielded no measurable movement, but I reassembled the knife anyway. No change in detent strength.

2. Next adjustment changed the lock bar position by ~.5mm**. No change in detent strength.

3. Next adjustment changed the lock bar position by ~1mm (total change of ~1.5 to 2mm). Detent was better. However, the lock up went from ~35% to >60% and was almost impossible to disengage.

Since this knife was an Amazon purchase, they can deal with it.

**My digital calipers were stolen during my last move in the USAF, therefore these measurements are Scientific WAGs (a toothpick and a clear plastic ruler were used).

Thanks for the info/help, I have learned a bunch reading this thread.
 
MajorHarryFace said:
From the newb's bench:

I 'adjusted' the lock bar's tension slowly and carefully with the following results:

1. First attempt at bending the lock bar yielded no measurable movement, but I reassembled the knife anyway. No change in detent strength.

2. Next adjustment changed the lock bar position by ~.5mm**. No change in detent strength.

3. Next adjustment changed the lock bar position by ~1mm (total change of ~1.5 to 2mm). Detent was better. However, the lock up went from ~35% to >60% and was almost impossible to disengage.

Since this knife was an Amazon purchase, they can deal with it.

**My digital calipers were stolen during my last move in the USAF, therefore these measurements are Scientific WAGs (a toothpick and a clear plastic ruler were used).

Thanks for the info/help, I have learned a bunch reading this thread.
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Sorry it didnt work out for you. I suspect there is something else wrong with your knife. You shouldnt get nearly double the lockbar engagement simply by tweaking the lockbar that small amount. The lockface on my 0560 was a curved lockface which would make that much lockup impossible. If your knife had a flat lock face there are still a number of factors that could have contributed to the later engagement. In your case sending it back was probably a wise choice.
 
I actually went the other direction with my 0801 which was stiff as a board. I removed the overtravel stop and bent it out just a tad (not really sure how to measure a tad) and it worked beautifully. Now i will carry this one...almost as smooth as my 0562 and still locks up tight. Thx for the suggestion.
 
My new (exchanged) 0561 just arrived. This one has the steel lock bar insert. The detent is "how detent is supposed to be"! Lock up is just below 50% (no lock rock), blade centering is perfect, zero blade play (open & closed), and it is noticeably sharper too.
 
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