Ball bearing pivot knives, a new opinion from me.

I believe that I posted some concerns on ball bearing pivots in the thread the op mentioned as well, and like the op I also bought a ball bearing pivot knife to use, test and find my own answers. I picked the ZT 0909 for my test mule.
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So what are my completely unscientific observations after several months of using it for hard, dirty ranch work?

Ball bearings seem to be just fine for me on a work knife.

They do get gunk in them easier. It's also quicker and easier to get that gunk back out, so to me that's a wash, pun intended. :D I do still believe that something like PB washers would likely be stronger in some loads, all other things being equal, than ball bearings due to spreading the load out over a much greater surface area. It also appears to me that this added strength is completely academic since the ball bearings have handled everything I've asked of them so far with absolutely no problems whatsoever.

My not so expert opinion on the issue? If you like the knife and it's from a quality manufacturer, don't worry about the pivot. Buy the knife and use it. The pivot will be just fine.

I will say that I do have a preferred pivot system for some of the sorts of extreme situations mentioned earlier in the thread. Things like no access to running water or any way to clean the pivot for a significant amount of time, wilderness survival, wood processing, an impending apocalypse, etc, where ball bearing pivots may theoretically not be up to the task. If those types of scenarios are really a concern for you when making your knife choices, I'd personally recommend sticking with the following pivot style.
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o_O
 
Wowbagger said:
That 'll do it !
Slow to pivot but QUIET and smooth !
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I think Hexenjager is pulling your leg sir

I d'loaded the image. Set it to ultra resolution. Converted the image to a 3D Blender file, and inspected the extrapolation very carefully with my brand new USB microscope.

There is no pivot in that knife.
Just sayin'
I am ready for zombies, and log/boulder piles.
 
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555 212-5555 Ask for Tilly...
 
palonej said:
Mine was the same Hex! Couldn't even find the damn pocket clip!
Terrible lock stick & they forgot to put the clip on???
I sent it back and bought a Ganzo! With no damn BB!!
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If only I'd known. I would have graciously offered to properly dispose of that obviously defective and unsafe knife and sent you the Ganzo of your choice along with a Vic Jetsetter to help you ease the pain of getting a lemon. :(
 
Quite gracious of you brother!!
A very selfless gesture!
:thumbsup:

hexenjager said:
If only I'd known. I would have graciously offered to properly dispose of that obviously defective and unsafe knife and sent you the Ganzo of your choice along with a Vic Jetsetter to help you ease the pain of getting a lemon. :(
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Did you really suggest some knives are meant to be fiddled with whilst the user sits at a desk? Knives are tools, not toys. Can it be enjoyable to fondle certain knives? Yep. Was the knife built for that reason? Nope. What a silly statement.
 
brandoak said:
who cares if Ken Onion or any real knife makers have been quoted saying that bearing knives (especially riding on titanium) are inferior......
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I don't care.
I base my opinions on how things are on my own experiences, when that is feasible.
Since I have knives with bearings, knives with washers, and a couple without either, I am quite easily able to make up my own mind on the subject.
Actually using these knives has shown that there is no problem.
Even using them for abusive tasks that the internet says should have thrown metal shards into my eyes has proven to be no problem. :thumbsup:

So, since there is no problem, I will conclude that there is no problem, based on the continued absence of problems.

It ain't rocket science, fellas, it's just using knives.
 
stabman said:
I don't care.
I base my opinions on how things are on my own experiences, when that is feasible.
Since I have knives with bearings, knives with washers, and a couple without either, I am quite easily able to make up my own mind on the subject.
Actually using these knives has shown that there is no problem.
Even using them for abusive tasks that the internet says should have thrown metal shards into my eyes has proven to be no problem. :thumbsup:

So, since there is no problem, I will conclude that there is no problem, based on the continued absence of problems.

It ain't rocket science, fellas, it's just using knives.
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Careful Stabby!
Around these parts of town we throw logic out the window and quote Wikipedia articles to prove knife-science.
 
Murdamook said:
Did you really suggest some knives are meant to be fiddled with whilst the user sits at a desk?
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Yes. Pulling staples, and cutting apples. maybe taking some gum off a shoe.

Murdamook said:
Was the knife built for that reason? Nope.
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Agreed. It was built to make a rather large profit from a targeted market.
These are niche knives, would you agree to that?

These are strictly my opinions. I have no disdain for these knives. I just do not see them as the sturdy work horses that some feel (in their opinion) they are.

Working on boats/ships/marinas/shipyards for more than 40 years has taught me that certain tools can save your life in certain situations.
Becoming tangled up in 3" docking line is no joke. reinforced hydraulic lines, a jammed watertight door, 2/0 battery cables melting to ground, there are many more examples of working situations where a ball bearing pocket folder is laughable at BEST, and deadly at worst.
A washer pivot lock back has the advantage, and with the money saved you can take your family on vacation (in some cases) or at least out for dinner.

For the office or the average farm use, perhaps a cop, maybe a job at the Home Depot shipping center... All for a bearing knife.
It's just not a sturdy work tool. IMHO
 
Zombie411 said:
Yes. Pulling staples, and cutting apples. maybe taking some gum off a shoe.



Agreed. It was built to make a rather large profit from a targeted market.
These are niche knives, would you agree to that?

These are strictly my opinions. I have no disdain for these knives. I just do not see them as the sturdy work horses that some feel (in their opinion) they are.

Working on boats/ships/marinas/shipyards for more than 40 years has taught me that certain tools can save your life in certain situations.
Becoming tangled up in 3" docking line is no joke. reinforced hydraulic lines, a jammed watertight door, 2/0 battery cables melting to ground, there are many more examples of working situations where a ball bearing pocket folder is laughable at BEST, and deadly at worst.
A washer pivot lock back has the advantage, and with the money saved you can take your family on vacation (in some cases) or at least out for dinner.

For the office or the average farm use, perhaps a cop, maybe a job at the Home Depot shipping center... All for a bearing knife.
It's just not a sturdy work tool. IMHO
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That's cute:p
 
I have read a few of articles regarding work-hardening of Ti alloy. It seems that machining does result in work hardening, which increases the surface hardness by 20~30% from the bulk hardness.

Assuming that this much hardening occurs at the pivot during repetitive usage, it still won’t match the hardness of even steel bearing balls.
(I started from this paper: http://www.sciencedirect.com/science/article/pii/S0924013604010313)
 
There is an enormous difference between machining, and bearings rolling on a surface.
In fact I do not really believe bearings will have any hardening effect on titanium. If there is an effect the bearings would have to be tremendously tight, and at that point the Ti would yield, and grove before hardening.
That alone would relieve the pressure, and there would be (again) no hardening.

I could (most likely) be completely wrong but it makes no sense.


Very cool video BTGuy.
I was surprised at how much steel he was loosing to oxidation. Very cool...
 
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Since the Ti scales do deform due to the ball grooving, cold hardening could occur. My point was that the effect may not go beyond what machining does and therefore negligible by itself (HRc increase from 40 to 50 would not be enough to match with the hardness of balls).

Spreading the force in the grooves may be more significant and work together with cold hardening to reduce extensive wear.

Anyway, I found some reports of "Brunelling" on Ti scales of ZT knives. So I guess it could happen in some ball bearing pivots.
 
I think some of our forum members are the original fidget spinner users, think knives such as the original Gerber Paul knife. I enjoyed fidgeting with it for many years.

Here is a great video for those who like physics, engineering, and other geeky pursuits that address fidgeting spinning and how to get the most out of it. I hope you enjoy it.

 
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