Are ball bearing pivots just a marketing gimmick?

[Sharp & Fiery]

R robgmn
“Going from folder to folder with bushings is a compromise”

Did you mean “washers” not bushings?

 

[marrenmiller]

This is philosophy, and not me trying to bash or berate ball bearings in any way. I've considered buying a knife with bearings just because they exist and I think it's interesting. I have a carbon fibre handlebar on my bike for the same reason. No weight savings, no strength increase that I'll ever exploit, BUT IT'S COOL.

Here's where I see a flaw in your argument against me: "Typical design intent is not to design something as strong as possible but rather the best for the intended use".
A knife is a tool used for cutting. You always want the knife as strong as possible for your own safety. How does having ball bearings between the blade and handle make the knife better at cutting? How does it insure the strongest/safest tool?Opening and closing the knife should 1/10 of a second of "use". The real purpose (cutting) should be far longer, and that's where you would normally focus your design efforts for a utilitarian product.

Now, maybe you have a job where you open, slice, close, open, slice, close all day long. THAT might be a good place for the benefit of bearings making that 1/10 of a second as enjoyable as possible (insert your own juvenile humor here ). Or, maybe you use the knife like a fidget spinner, or have a butterfly knife. Both good places for silky smooth action.

On a utility knife? Nope. It's antithetical to the whole philosophy of making the best & strongest tool possible.
Going from full tang to partial tang on a fixed blade is a compromise.
Going from fixed to folder is a compromise.
Going from folder to folder with bushings is a compromise.
Going from bushings to bearings is a compromise.
It's just the way it is from a mechanical/engineering standpoint.

Does it really make a difference? For all practical purposes, I'm sure it doesn't. I know for a fact that none of my knives except perhaps one are ever pushed close to their capability and are thus over-designed for my purposes. I'm sure a knife with bearings would be the same. I'll bet most people are the same (witness how many people sell their EDC that looks like it just came out of the box).

But, I'm not talking about what usually happens. I'm talking about the technical reality. Two different worlds.

A folding knife is a tool used for cutting, not for prying edge wise against your bearing suspension pivot system. Knives are not made to be as strong as possible (and in fact that's a pursuit that's antithetical to blade geometry), but it's a fact that one of a folding knife's primary functions is to fold open and closed. Properly implemented ball bearings do that easier, if only slightly, than bushings/washers. Meanwhile, they are only potentially an issue in use cases that are distinctly not in the scope of knife use.

I am an actual licensed professional mechanical engineer, and in my circle of friends we have a joke about people that always want to make something stronger and stronger: "What about 3 bolts? Well, what about 4? How about 5? 6?" At a certain point, you no longer need more strength or durability. The "technical reality" is that engineers design things to be as strong as they need to be, because any more so is unnecessary cost, added weight and/or complexity, and at times at odds with with intended use of the item.

If your philosophy really is that a folding knife should be as strong as possible, then I hope you also don't own any frame or liner locks before you start pinpointing ball bearings as an unnecessarily weak link in folding knife design. Ball bearing failure generally won't result in a knife closing on your hand.

Edit: not to discount personal opinion or anything, but just the fact that there are a ton of people here who don't like cold steel's triad lock knives would indicate that strength isn't everything people consider in functional cutting tools. With that being said, I also love those kinds of knives.

 

[marrenmiller]

R robgmn
“Going from folder to folder with bushings is a compromise”

Did you mean “washers” not bushings?

Washers are a form of bushing

 

[Sharp & Fiery]

So a Crk Sebenza has three bushings then...
I learn something new everyday.

Washers are a form of bushing

 

[marrenmiller]

So a Crk Sebenza has three bushings then...
I learn something new everyday.

Actually, I think I misspoke. A bushing is a form of bearing for radial loads (like the bushing pivot). A washer should properly be called a thrust bearing. I've just heard the term "bushing" being (evidently incorrectly) used so often to describe washers.

 

[Sharp & Fiery]

Actually, I think I misspoke. A bushing is a form of bearing for radial loads (like the bushing pivot). A washer should properly be called a thrust bearing. I've just heard the term "bushing" being (evidently incorrectly) used so often to describe washers.

This I agree with!
Im so tired today, i couldnt even pull “thrust bearings” out of my brain. Glad one of us could. Lol.

 

[kefefs]

No, it's not a gimmick. When done well they can make for an incredible action. I've owned $30 ball bearing folders with better actions than $150 ones with PB washers.

This is my $35 CH Toucans on bearings. It has one of the best actions I've ever felt and drops shut like a champ.

 

[uraninite]

Gimmick to me. Hard(er) for users to maintain, extra moving parts on a device that should follow KISS (to some extent) and add to the cost without adding to the functionality. On the other hand, they add to the fun of the knife. Autos could be called a gimmick too, for the same reasons, but I think most of us here can´t help but grin when we pop open a fast snappy auto. Same goes for flipping open a super smooth ball bearing flipper. At some point a knife starts to transcend its tool roots and becomes art.

 

[sharp_edge]

Bearings are an evolution forward from washers, but kinda forward and to the side. Bearings are superior in some ways and inferior in others. They reduce the necessary tolerances on the pivot and in most knives allow the pivot to be fully tightened to the point of no play but have extremely free action because the bearings roll not drag like a washer. They are technically easier to clean, requiring less lubrication and being able to be ran dry and still give decent action, or working fine with oil or grease, where washers usually respond best to grease and oil will work its way out. They are more prone to damage from overtightening and are more vulnerable to debris clogging them up. If ran dry, bearings are capable of rusting, although it is mitigated with ceramic.

Overall I think bearings are an improvement over washers, but they aren't the end all be all of pivot friction reduction technology. There's stuff like Protech and Hogue uses that has a completely washer free design, which is another side evolution. The tech is ever moving forward and innovation will likely eventually render bearings obsolete.

The real improvement we need to talk about because there is no argument to be had on it, and all manufacturers need to get on board with, is ceramic defend balls. Steel balls eventually wear out, ceramic has a nearly indefinite lifespan. The lock will likely wear out before the detent ball. I've had multiple knives have a steel ball that ran flat, and once they do the detent turns to garbage, and only some manufacturers will warrant a worn out detent ball. The cost difference is absolutely negligible, which the ceramic balls are substantially more expensive you're looking at a few cents a piece tops. Spyderco is finally starting to switch to ceramic on some of their CQI knives, and virtually all Chinese knives come with ceramic detents. Get on it!

I have a ZT 0562 currently being serviced at KAI warranty department. It was a smooth folder back to some time ago. Then the action gradually deteriorated, to the point that it can no longer reliably be flipped open fully. The detent ball has become obviously flat, though I am not sure if it is the reason. Another thing is a deeper bearing track has been formed on the ti side of the pivot. I dont know if the track is so deep that the plastic cage begins to contact the ti scale. Granted this is one of the oldest flippers for me and also perhaps the most flipped (thousands times), and I have no idea how many times its previous owner(s) flipped it.

I am interested in learning how KAI fixes the issue or if they will successfully fix it.

 

[robgmn]

A folding knife is a tool used for cutting, not for prying edge wise against your bearing suspension pivot system. Knives are not made to be as strong as possible (and in fact that's a pursuit that's antithetical to blade geometry), but it's a fact that one of a folding knife's primary functions is to fold open and closed. Properly implemented ball bearings do that easier, if only slightly, than bushings/washers. Meanwhile, they are only potentially an issue in use cases that are distinctly not in the scope of knife use.

I am an actual licensed professional mechanical engineer, and in my circle of friends we have a joke about people that always want to make something stronger and stronger: "What about 3 bolts? Well, what about 4? How about 5? 6?" At a certain point, you no longer need more strength or durability. The "technical reality" is that engineers design things to be as strong as they need to be, because any more so is unnecessary cost, added weight and/or complexity, and at times at odds with with intended use of the item.

If your philosophy really is that a folding knife should be as strong as possible, then I hope you also don't own any frame or liner locks before you start pinpointing ball bearings as an unnecessarily weak link in folding knife design. Ball bearing failure generally won't result in a knife closing on your hand.

Edit: not to discount personal opinion or anything, but just the fact that there are a ton of people here who don't like cold steel's triad lock knives would indicate that strength isn't everything people consider in functional cutting tools. With that being said, I also love those kinds of knives.

You missed my pint almost entirely. And that's OK. I at least hope you DID catch that I know even "weakened" tools are rarely used to a point that approaches their mechanical limits.

But, I'll ask you to clarify "it's a fact that one of a folding knife's primary functions is to fold open and closed".
Making a knife fold is a compromise of mechanical integrity. It adds convenience at the sake of strength. It's a "function" per se, but how is it "primary"? It adds nothing to the cutting ability of the knife. Cutting being the only "true" function of a knife.

Again, I'm talking the "big picture" discussion of the main thread topic.
I DO understand that reality is different (read back to my mention of carbon-fibre handlebars on my bike).

 

[CPP]

If a knife is updated with bearings after having working perfectly fine without I'd say it's likely a gimmick. In general, however, bearings are definitely a progression. The purpose of any opening mechanism is obviously to open the knife reliably and safely so if bearings make that mechanism more effective and efficient then it's definitely an improvement–especially on knives with flippers. To digress a bit, having bearings on knives without flippers doesn't seem to add much to the opening mechanism. Based on my reasoning I prefer flippers to have bearings and non-flippers to have bushings. I have a knife that shall remain nameless that has an updated detent system and washers and opens using a thumb disk but it works too well: it's as though my thumb can't keep up with the blade as it's opening resulting in cuts on my thumb. So were that knife to have bearings I might not have a thumb.

 

[marrenmiller]

You missed my pint almost entirely. And that's OK. I at least hope you DID catch that I know even "weakened" tools are rarely used to a point that approaches their mechanical limits.

But, I'll ask you to clarify "it's a fact that one of a folding knife's primary functions is to fold open and closed".
Making a knife fold is a compromise of mechanical integrity. It adds convenience at the sake of strength. It's a "function" per se, but how is it "primary"? It adds nothing to the cutting ability of the knife. Cutting being the only "true" function of a knife.

Again, I'm talking the "big picture" discussion of the main thread topic.
I DO understand that reality is different (read back to my mention of carbon-fibre handlebars on my bike).

At the risk of sounding rude, are you even trying to make a point? I am perplexed at to what you are trying to convey here, despite you writing that it's just "philosophy". You're stating that you believe you understand how design actually works, but you seemingly contradict that statement by not grasping the concept that something isn't a gimmick if it provides value to people.

The main thread topic is if ball bearing pivots are a marketing gimmick. People have presented definitive reasons why they believe ball bearing pivots offer small but in some cases meaningful improvements for the folding knife world, and your response seems to be: "Folding open and closed isn't something knives need to do, and ball bearing pivots are bad because it's too much of a compromise along the entirely subjective sliding scale I've laid out." I mean, how does anyone even reason with that kind of logic? Clearly people have different use cases for folding knives than I, but I wouldn't go around calling the knives I don't like gimmicky because I don't personally have a use for them.

 

[Basp2005]

I don't want anything to do with loose bearings. If a knife has that "feature" I'm not buying it. Captured bearings are fine, and fun. But a dedicated "hard use" knife should have phosphor bronze washers. Easier to clean and maintain with less chance of gunk getting in. Ymmv.

 

[soc_monki]

Gimmick to me. Hard(er) for users to maintain, extra moving parts on a device that should follow KISS (to some extent) and add to the cost without adding to the functionality. On the other hand, they add to the fun of the knife. Autos could be called a gimmick too, for the same reasons, but I think most of us here can´t help but grin when we pop open a fast snappy auto. Same goes for flipping open a super smooth ball bearing flipper. At some point a knife starts to transcend its tool roots and becomes art.

Harder to maintain? Caged bearings are no harder to maintain than pb washers. The knives are assembled the same, so it's basically the same level of difficulty. Now loose bearings... I don't think I'll buy a knife with loose bearings but if I did it would add just a little complexity. But I'd prefer caged.

I don't think they are a gimmick, I just think they are a different option. I like my bearings (0562, 0470, Amalgam...) but I like my washers too (manix, PM2, Para 3...). There are a ton of choices so if someone doesn't like bearings then there are other knives to buy. I like both, and will put both through the same tasks. They all have a lifetime warranty so if something happens and the knife fails I'll use that warranty. However I don't try to chop down trees with my knives so I doubt I'll have a failure!

I'll continue to buy both.

 

[robgmn]

At the risk of sounding rude, are you even trying to make a point? I am perplexed at to what you are trying to convey here, despite you writing that it's just "philosophy". You're stating that you believe you understand how design actually works, but you seemingly contradict that statement by not grasping the concept that something isn't a gimmick if it provides value to people.

The main thread topic is if ball bearing pivots are a marketing gimmick. People have presented definitive reasons why they believe ball bearing pivots offer small but in some cases meaningful improvements for the folding knife world, and your response seems to be: "Folding open and closed isn't something knives need to do, and ball bearing pivots are bad because it's too much of a compromise along the entirely subjective sliding scale I've laid out." I mean, how does anyone even reason with that kind of logic? Clearly people have different use cases for folding knives than I, but I wouldn't go around calling the knives I don't like gimmicky because I don't personally have a use for them.

Reread my posts and you might get a better understanding.
"Marketing gimmick"? Probably not. More like "unnecessary add-on that doesn't truly enhance the job a knife should do", which is to CUT. Put a gold handle inlaid with diamonds on your dull kitchen knife. It's "enhanced". Have fun prepping dinner with it.


Physics, mechanics, engineering, are not "subjective". They are fact-based.
You can SAY I'm wrong in my statements. You may BELIEVE I'm wrong in my statements.
But, you cannot prove it, because my statements are based in fact and not opinion. Some people truly dislike that. I find it odd, but we're all unique and that ain;t gonna' change.

.I'm not a knifemaker, but I've made a knife. I stuck to the very basic principles of full-tang, robust shape, very hard wood handle. It's old-school, but you know what? Those old-school ways worked, and worked well for a reason. I'll bet you a lunch that the more complicated a knife becomes, the higher the failure rate for that model. Be interesting to know the stats on how many folding knives fail compared to one-piece knives at the same approximate quality level (don't compare a WalMart folder to a Reeve one piece or vice versa)...

 

[Tseg]

More like "unnecessary add-on that doesn't truly enhance the job a knife should do", which is to CUT.

If a knife was only meant to cut, folding knives would not exist. They only cut when open. But why do they exist? Oh, because they have the additional job of adding safe transport. Diamonds in knives? An expression of art? An expression of wealth? Implying a knife’s job is binary is projecting.

 

[robgmn]

If a knife was only meant to cut, folding knives would not exist. They only cut when open. But why do they exist? Oh, because they have the additional job of adding safe transport. Diamonds in knives? An expression of art? An expression of wealth? Implying a knife’s job is binary is projecting.

A knife exists to cut, not "provide safe transport" or fold. If it existed to provide safe transport or fold, there would be no need to sharpen the blade or even have a blade.
Safe transport? Sheath. They've existed far longer than folders.

But again, don't lose sight of what I said in my original post and try to paint me as anti-folding knife, anti-ball bearing, etc.
They're all fine, but don't try to make them into something they're not.

 

[ColoradoHoldout]

I have owned a lot of folders and most of them used some type of washer system for smooth opening action. I bought a Topps Mini Scandi folder and it's the first knife I've owned that has bearings. I've used it for very light use for about a year and now there is a lot of play in the blade even though the screws are as tight as they should be. Now I'm thinking I need to take it apart and replace the bearings to fix it.

In the past I have just taken knives apart and cleaned and oiled them fairly easily and the whole bearing thing seems like a huge pain to be honest. Are bearings just a marketing gimmick? To me it seems like more work and less durability for little noticeable benefit. Would love to hear other opinions.

I love ball bearing systems. Some of my favorite knives, the ones that have the most satisfying 'feel' to their action, had ball bearings, like the Swish or Reate Baby machine.

 

[ColoradoHoldout]

*Philsophizing*

From a mechanical standpoint, the strongest knife will be a one-piece.
If two piece-folder, you want to make it as much like a one-piece as possible, which means having the handle and blade locked together as tightly as possible.
Using a washer means the contact point between the parts is the surface area of that washer x2. Which is less surface contact than if there were no washer/bushing.
Using ball bearings means the contact point(s) between blade and handle are now 100x less than they would be with a washer/bushing, and 500x less than if there were no washer/bushing. I completely made those numbers up.

Since a folding knife is for cutting, and we want the "bond" between blade and handle to be as strong as possible, how does reducing the contact patch between blade and handle add a benefit?

Because the benefit doesn't come from strength or durability. The benefit of bearings is to improve the smoothness and action of the knife. There is definitely a difference in how the action feels, and some people, like myself really prefer the 'feel' of bearings.