Are there any disadvantages of ball bearing pivots?

[cptkomondor]

I can't think of any reason not to have them besides price and simplicity, especially since ceramic bearings don't deform and aren't going to break. Why don't folders use this?

 

[The Aflac Duck]

Bearings don't cost that much to implement into a design, there are cheap knives with bearings. Even kershaw has some budget KVT knives. A well designed washer system can be just as good as a well designed bearing system, so it really doesn't matter IMO.

Washers are pretty tried-and-true for folders, and have been for much longer than bearings have. Not to say that bearings are bad, I love them! However, they are new, and there are so many types of bearing systems out there now, it just seems like a lot of hype. Who knows if all these designs will last or not? Who knows how they will wear over 20 years of use?

 

[EChoil]

I have some bearing flippers but would hesitate to take them into a survival or extended outdoor situation until I see more studies, reviews or posts on how they do in the wild for extended periods....gunk, muck and junk.

At what point do they become affected as compared to a comparable washered knife...how do they operate after days of rain or river running has washed all the lube from the bearings...how do they operate after being buried in the sand for a week...what will disable them....how do the bearing baskets handle extreme side torquing and lateral stress, batoning etc....?

What happens when they get gunked up with grass, dirt and weeds doing light duty in my yard? Do I have to take em apart and clean them or can I just spray them out at the car wash?

 

[Final Option]

IMHO I believe folding knives with ball bearings were created and marketed to satisfy the quest to achieve glassy smooth opening. Some folks get so hung up with how a knife opens this has become a focal point, however long range performance in harsh environments may be questionable. That being said my fixed blade is always the primary load carrier and the folder whether washers or bearings is delegated to non fixed blade tasks. I have several folders in the washer and ball bearing configuration, however the ball bearing systems has many moving components to be compromised so in descending order of reliability in harsh environments would be fixed blade, washers, then ball bearings.
In the mean time enjoy either system and it's nice to have choices.

 

[toker]

The other disadvantage of the loose ball bearing style is ease of maintenance. It's much more difficult to disassemble/reassemble than a cage bearing style.

 

[PURPLEDC]

I see no real disadvantage to a bearing equipped knife as long as the components are manufactured properly. Which the same can be said of a knife with washers. And as long as the product is used and maintained in accordance with what the manufacturer intended there should be no shortcomings to be had. Some people feel bearing systems are a new fad. In production knives this may be true but in the custom world there are knives that predate IKBS folders utilizing bearings. RJ Martin has been using a captive thrust needle bearing system for many years. Its bearings in production knives that has more recently gained steam. But even bearings in productions is going on 7 or 8 years now.

 

[MatthewSB]

After using knives with Phosphor Bronze washers for 20 years, and experiencing some truly slick opening folders (old liner lock benchmades, current ZTs like the 0620CF, Sebenzas) I'm not sure I see the point of ball bearing pivots.

I consider ball bearing pivots the same as the Axis lock - a corner cutting, cost saving measure that allows for sloppier knives to feel slick and smooth while unnecessarily complicating a design.

I'll stick with PB washers and liner (or frame) locks, they are very smooth and reliable when built properly and are brilliantly simple.

 

[PURPLEDC]

After using knives with Phosphor Bronze washers for 20 years, and experiencing some truly slick opening folders (old liner lock benchmades, current ZTs like the 0620CF, Sebenzas) I'm not sure I see the point of ball bearing pivots.

I consider ball bearing pivots the same as the Axis lock - a corner cutting, cost saving measure that allows for sloppier knives to feel slick and smooth while unnecessarily complicating a design.

I'll stick with PB washers and liner (or frame) locks, they are very smooth and reliable when built properly and are brilliantly simple.

Honestly I think you may be looking at it a little wrong. People always focus on the smoothness of bearings compared to a washer knife. But I think people confuse smooth with speed. Washers can be just as smooth as bearings. But they are rarely as fast. I dont really agree that they allow for a sloppier design. In fact the reason I love bearing knives so much is because it forces the maker to use better tolerances by default. With a washer knife if you have proper spec washers and handle slabs that are true you can usually get a pretty centered blade especially because the design usually will have some give and if a blade isnt centered it has some semblance of adjustability and you are relying on your stock materials to be true in order to center properly.

On a bearing knife you need to be more precise in how you make the blade as well as the handles. Most bearing knives have a pocket milled out of the handle, blade or both in order to house the bearings. If these cups are cut improperly or off axis even by a slight amount you are going to have an off center blade or even worse binding at certain points of travel as the blade swings. Sometimes even both issues occur. The real advantage of a ball bearing pivot is to reduce friction at the pivot and if properly machined is completely self centering. Its this reduction in friction that increases the speed of the opening. Sometimes you can get a poorly machined bearing knife to center by backing off the pivot screw. Then the lockbar pushes the blade to center but this usually leaves you with a fair amount of lateral play. This is usually covered up by the lockbar when open but if you disengage the lock and wiggle the blade you see just how much slop there is. The smoothness is all in how much pressure you set the lockbar to and what size and type of detent ball you are using as well as the finish you choose for the blade. Another awesome feature about a bearing pivot is because of the reduced friction the end user can tighten the pivot sufficiently enough as to eliminate all play and be tightened down much tighter than a washer equipped knife and still have the parts move freely. Often eliminating the need for loctite at the pivot.