Bearings and Washers

Shorttime said:
Now we need somebody to take apart a 0606.

Anybody.....?

Um.

"Designed by RJ Martin and built by Matt Martin, the 0606CF‘s pivot cartridge features loose ball bearings in a hardened-steel bearing race for an incredibly smooth opening—and virtually no pivot wear during the knife’s lifetime."

From ZT's Tumblr feed. A hard steel race, which is a good thing. But not needle bearings, which would would be even better.
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However i saw Nick Shabazz's review of it and it seems like the usual KVT, by the look of the blue plastic washers?

Sent from the BatComputer
 
Glenn056,

I buy a lot of used knives, probably TSA confiscations 99% of which are production stuff like Emerson, Kershaw, Gerber, ZT, Protech. They all are varied in the type of pivot washers they use.

I always take them apart but before I do, I snug the pivot so that there is zero side to side play and I lube the pivot with some simple sewing machine oil. It usually smoothes it out completely no matter what the pivot material is.

Then I proceed to take them apart just to see what's in there, let me tell you, I find some of the dirtiest nastiest crud molded around the pivot and under the washers on most of them. It seems that the bronze phosphor washers are the ones that get the most damage. With that said, they still seem to function fairly well once lubed! It surprises me every time Lol.

The only time the gritty-ness won't go away is when there is rust.....but dirt, sand, pocket lint are never a problem with lube added. If the pivot is fairly tight, it is very difficult for sand, crud, lint to get beneath the washers. *If sand would get under ANY of the washers, it would probably scratch up the washers pretty bad not sure how much damage it could do to bearings.

From the smallest of the pivot washers to the broadest flattest ones. I have not seen much if any difference in the function of a knife no matter the washers when it it properly cleaned and lubed.

Protech and CRK use very broad diameter washers. Phosphor bronze for the CRK and nylon for the Protech TR3 integrity. To me, they both feel and have felt very smooth for the longest time. They get dirty and gritty, I clean them and they go back to feeling like new. I have never felt any flex from the nylon washers off of the Protech Integrity and none from the CRK's. I actually think (in my humble opinion) that the TR3 feels a bit smoother.

Bearings are a different story, there is so much open space for dirt, lint and sand to get in there. If I were going to a sandy place for an extended period, my first choice would NOT be a bearing knife. I don't think it impairs the function too much but I can't stand that grinding noise. The one thing I will say about bearing pivot knives, if they are machined right, they are 99.9999% of the time very well centered and still flip open nicely no matter the tightness of the pivot. Try over tightening a washer knife by just a teeny bit and see how well / fluid it opens :)

My favorite pivots in order are

1: Bearings (they just run smoother)

2: Nylon (i find them the smoother than Bronze Phos)

3: Bronze Phosphor (I think they are more susceptible to scratching and only work best when polished. But they seem delicate and can scratch easily)

As far as the prybar type of knife, in order to damage the bearings, you would have to make one or a few of the bearings "out of round" or have it fail / crush completely. But like I said earlier, you can snug the pivot up pretty tight on a bearing knife and that in turn give the bearings a tremendous amount of support. I have never heard of any bearings used in a pivot fail under stress. I would be curious to know if anyone has ever come across this.

Really liking the sealed needle bearing option... I hope someone gets on it!
 
I would think rather than the bearing being damaged, the scale it's riding on would dimple and potentially allow blade play when being used hard. The balls themselves seem unlikely to be the spot damaged.
 
benzy2 said:
I would think rather than the bearing being damaged, the scale it's riding on would dimple and potentially allow blade play when being used hard. The balls themselves seem unlikely to be the spot damaged.
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^This. I have no idea why one of my favorite titanium flippers got some dimples on the ball bearing track. The knife is never used (though it has been flipped open many times). I am not 100% but I suspect the gritty action of the knife may have something to do with the dimples.:(
 
sharp_edge said:
^This. I have no idea why one of my favorite titanium flippers got some dimples on the ball bearing track. The knife is never used (though it has been flipped open many times). I am not 100% but I suspect the gritty action of the knife may have something to do with the dimples.:(
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Damn, and i just got a brand new zt0562cf yesterday and have been flipping it several times to break it, as now the action feels kinda gritty as well... Hope it's just dust...

Sent from the BatComputer
 
i HATE Nylon washers. i love PB or Bearings. i love bearings more than PB only because some PB washer knives just suck at opening regardless and i dont get that issue with most ball bearing knives, but its hugely not an issue for most PB knives.

nylon washers i just want to freaking scream at the manufacture who decided to put those in to save a few pennies.

i like flippers alot, im a fidgeter, but do enjoy other opening mechanisms. im not a fan of slowly opening knives.
 
Shorttime said:
This:

oyDOS9m.jpg


Scaled down to knife-size, would be about as good as you can get. The bearings are conical, allowing them to be closer together, so there are more of them in the race than there would be with needle bearings or balls.

Machining cone-shaped bearings that are less than 1/8" in length would be quite a feat. They might have to be sintered, and I have no idea how heat treating would be done.
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I would add one modification: The race should be re-designed with an L-flange and rubber seal. That way it can be grease filled and lubed for life. With the seal, dirt and grit will not get in the bearing.

The comments about friction of the roller bearing are not really relevant. Roller bearings have much lower friction than teflon washers - due to rolling vs sliding.

Dan
 
I have had zero issues with bearings.
They have stood up well to what I do with my knives.

That being said, I prefer PB washers over anything. Simple, durable, and I am not really all that into flippers or the Maximum speed at which I can deploy a blade. (I actually prefer the "mechanical" feel of a flipper on washers vs the "Auto" feel of a flipper on bearings...)
 
Seeing a track forming in my 0562cf after minimal use, I'd prefer not to buy bearing knives that do not at least have a steel insert to protect the titanium side. That said, I love the way the 0560 goes back together with almost no centering adjustments needed. Not sure of the long term durability of bearing knives, but mine have mostly been relegated to safe queen status.
 
Shorttime said:
I think in terms of utility, so the way a knife pivot feels is not that important. But comparing the mechanical strength of washers and pivots? Fascinating.

The washers are a better bet for shock-loading. Ball bearings are able to withstand quite a lot of impact force, but they shatter when they fail. Washers will compress by a tiny fraction of an inch, then transmit the mechanical stress to the rest of the knife.

Bearings win the crush test. They will shatter eventually, but the washers deform first, squishing out the sides of the knife like Play-Doh.

Either of these scenarios implies ludicrous amounts of force, that would destroy either the blade or the lock mechanism first. I understand the framework of the discussion, but it's easy to lose focus and perspective when we're all so deeply absorbed by these technical details. So I'm reminding myself, as much as everybody else.

Thrust bearings are designed to handle much more axial torque than ball bearings. To the best of my knowledge, nobody has scaled them down to knife-pivot sizes, yet. I think a lot of the "ultimate strength" of a bearing relies on metallurgy, and the question of "needle versus ball" bearings in a knife pivot should be for another thread.
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Actually there a few makers that use thrust bearings. Ferrum Forge is one that comes to mind...
Russ
 
Basp2005 said:
Seeing a track forming in my 0562cf after minimal use, I'd prefer not to buy bearing knives that do not at least have a steel insert to protect the titanium side. That said, I love the way the 0560 goes back together with almost no centering adjustments needed. Not sure of the long term durability of bearing knives, but mine have mostly been relegated to safe queen status.
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I wonder if this has to do with the tightness of yhe pivot screw. Say, if I loosen it to the point where blade play is just about to appear but not yet, that will keep the pressure on the ti scale by the bearing balls to a minimal level, which can at least delay the formation of that bearing trace.
 
sharp_edge said:
I wonder if this has to do with the tightness of yhe pivot screw. Say, if I loosen it to the point where blade play is just about to appear but not yet, that will keep the pressure on the ti scale by the bearing balls to a minimal level, which can at least delay the formation of that bearing trace.
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Yeah, that's about the best I can do. Will see how it does over time.
 
However I heard that titanium can be work hardened? So the bearings would only cut into the titanium a tiny bit and that's it?

Sent from the BatComputer
 
No washers?
Hogue.
In fact I just picked up 2 of their X5 flippers and even they don't have washers.
And they flip just fine. The 4" does flip a bit easier/smoother than the 3.5" though.
 
Ferrum Forge's thrust bearings are pure glory. Awesome action, rock solid in use. Feels like a fixed blade.
 
GB940Rookie said:
Not a huge fan of bearings and flippers. Don't own any. It's what's kept me away from ZTs. If only the 0909 had washers and a thumb stud, I'd be all over it.

Not downgrading them. It's just not my thing.
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Imo the zt 0850 is one of the smoothest knives running on washers ive experienced
 
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