Ball Bearing Pivots - smooth as silk or full of grit?

I

iht@intekom.co.za

Joined
Jun 19, 2004
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I note Darrel Ralph has started using a ball bearing system for his framelock knives as he does for his balisongs. As far as I can understand the ball bearings take the place of washers, and surround the pivot lying in a groove but not sealed. Sounds great for showing off your flipping skills with a balisong but in the real world of EDC how do they perform
1) my understanding with framelocks is that most of the resistance to blade opening comes not from the pivot, but from the ball detent on the framelock rubbing on the blade as it opens - and there lies the problem for smooth opening, not the pivot. So do ball bearings really make a smoother opening knife
2) We all try to avoid muck and especially grit getting into our knives - but it does happen, and having open ball bearings sounds like open house for any piece of muck to get in and stay in.
I hope someone can put my mind at rest because I think Darrel's knives look fantastic, and have no doubt are executed with superlative attention to detail, and I would really like to hear from users of such knives as to their experience.
 
Well, I don't have any experience with long-term use of a bearing assisted knife, but I've never seen anyone unhappy with the IKBS system Korth uses (which is also ball bearing based). RJ Martin uses Thrust washers, and to be sure they make for a smoother opening. Most of the resistence IS from the detent, but after you overcome the detent a bearing-type system WILL smooth out the opening because it has less drag than regular washers. As far as muck getting into it, all you need is to soak the knife, or coat it in something like WD40 and blow out the dirt. Easy pleasy. Its really no more difficult to clean than washers, and Darrell is no slouch when it comes to engineering his products. He wouldn't bring it out if it didn't work.

For another maker using this type of thing, Mike Draper is going to start making flippers that have polished jewels in the pivot (called the J-Mac system). Should be SWEET!!!
 
Also, if it got really full of junk, it wouldn't be too hard to take it apart, clean it with degreaser and repack it.
 
Since I would love to have a RJ Martin Devastator (trying to save up for one), I've read up on them as much as possible and it appears they have a sealed bearing/thrust washer system. If I'm wrong then please correct me.
 
Cutter17, the Devastator uses Thrust washers that are placed in precise machined pockets in the frame. You can think of the Thrust washers as being round plastic (teflon?) washers that have barrel-shaped rollers placed around the pivot. When you roll them around between your fingers it feels like liquid. The rollers move on spindles in the washer, and make contact with the frame and the blade. Altogether, they're a VERY good (and expensive @ $2 a piece) way of smoothing out the action. NO WRIST ACTION NECESSARY!!!

Make sure to have RJ explain how to open a flipper correctly when you get yours. I had trouble getting the Devastator to open fully every time until he explained the proper technique.

By the by if you'd like to have a VERY good knife that is a bit smaller than the Devastator- and still has the thrust washers and flipper- then I'd suggest trying his new Havoc. Its a VERY slick little knife that'll debut at Blade this year!
 
I think it all relates to preventive maintenance no matter what type of bearings/washers are used. I have never had a problem with any of my flippes knives using ball bearings, needles bearings, etc. because I keep them clean of lint, grit, etc. When I feel a knife is not operating as smooth as it normally does then know it is time to clean it. I have had more problems with regular washers over the more intricated versions.
I love my R J Martin Devastator, and there is a trick to opening it to make it work flawlessly which cmoes in practice, and is one of my favorites but of all of the ones I own or have owned the Larry Chew needle bearing system is the best I have seen but with the new developements coming out by makers they are getting even better.
And what is said here about lockbar pressure, and the detent is a major factor is the smoothness of operation.

Larry
 
Just to set the record straight, the bearing system that DDR is using in his balis and flippers is the IKBS (Ikoma-Korth Bearing System). This is the same system that Korth and Ikoma developed and use in all their knives. This was licensed to DDR for use in his knives.

I have carried Korth and Ikoma IKBS fitted balis and folders for at least 3 years and have never heard a complaint, and have not had any problems with the knives of theirs I have used either. Since it is an open system, pretty much any gunk that finds it's way into the bearings finds it's way out just as easily.

Charles Marlowe is also licensed to use the IKBS and currently uses it in his balis.
 
iht@intekom.co.za said:
1) my understanding with framelocks is that most of the resistance to blade opening comes not from the pivot, but from the ball detent on the framelock rubbing on the blade as it opens - and there lies the problem for smooth opening, not the pivot. So do ball bearings really make a smoother opening knife
That's by design and it isn't a problem, it's a solution. A framelock without a strong detent ball is a gravity knife which can be opened by statutory "wrist movement," and is illegal just about everywhere in America.

Darrel Ralph's Gun Hammer and RJ Martin's Devastator are amazingly fast manual-opening flippers. They get their speed from all the leverage they build up against their tuned detent devices and pass through the low, low-friction pivot/frame interfaces. They are smooth opening knives, indeed, and faster than I think anyone can describe with words.

Look for an upcoming article in TACTICAL KNIVES magazine about these very same knives and their opening systems.
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Rather than start a new thread, I am wondering if any production knifes have started using bearings in their pivot.

More specifically any knifes that do not use frame or liner locks.
 
Hypermole said:
Rather than start a new thread, I am wondering if any production knifes have started using bearings in their pivot.

More specifically any knifes that do not use frame or liner locks.
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Is this really the only thread you could find that talks about bearing pivots?

There are a bunch of bearing pivot production knives out there not but they are all liner/frame locks.

What other type of lock do you want bearings in?
 
iht@intekom.co.za said:
my understanding with framelocks is that most of the resistance to blade opening comes not from the pivot, but from the ball detent on the framelock rubbing on the blade as it opens
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Correct, this is why I don't understand all those folks polishing the washers on their Sebenzas. If the pivot is already smooth as can be, and mine was (even when it was new), polishing washers ain't gonna do much. Just let in break in.

A ball bearing is a very sterile mechanism. As soon as any dust or grit gets in there, you're going to have poor action and excessive uneven wear. In my opinion if you've got a good phosphor bronze or nylatron washer pivot, there is no need for ball bearings. They can be plenty smooth if done properly and are alot more resistant to contamination, especially if you used a teflon grease rather than a thin oil. I would take extra care keeping bearing pivot knives clean. Unless the knife is a flipper I don't care for bearings. I never "flick" my knives out unless it's a flipper or an Axis lock. But even then I've had some that were pretty smooth, center perfectly, and have zero play. Still there is no denying that the best flippers have bearing systems.

I have my sights set on a Grimsmo Norseman next. I hear those are the phenomenally good.
 
bicycles used open ball bearing systems in the hub of their wheels for a long time. These bearings generally see more dirt and grime than the average knife pivot, not to mention the loads on these bearings are exceptionally higher, as well as much higher rotational speeds... and they do just fine. I just serviced the original hubs on my road bike from 1995, and I'm not sure if the bearings were ever serviced before this, besides adjusting play. The cup and cone were both in good shape, the grease was dirty as hell and the bearing were all replaced, but a little degreasing then regreasing and it spun like a brand new wheel...

theoretically you can get way more junk caught up in there I guess, but it's not something I'd worry about.
 
Moxy said:
Correct, this is why I don't understand all those folks polishing the washers on their Sebenzas. If the pivot is already smooth as can be, and mine was (even when it was new), polishing washers ain't gonna do much. Just let in break in.

A ball bearing is a very sterile mechanism. As soon as any dust or grit gets in there, you're going to have poor action and excessive uneven wear. In my opinion if you've got a good phosphor bronze or nylatron washer pivot, there is no need for ball bearings. They can be plenty smooth if done properly and are alot more resistant to contamination, especially if you used a teflon grease rather than a thin oil. I would take extra care keeping bearing pivot knives clean. Unless the knife is a flipper I don't care for bearings. I never "flick" my knives out unless it's a flipper or an Axis lock. But even then I've had some that were pretty smooth, center perfectly, and have zero play. Still there is no denying that the best flippers have bearing systems.

I have my sights set on a Grimsmo Norseman next. I hear those are the phenomenally good.
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goodeyesniper said:
bicycles used open ball bearing systems in the hub of their wheels for a long time. These bearings generally see more dirt and grime than the average knife pivot, not to mention the loads on these bearings are exceptionally higher, as well as much higher rotational speeds... and they do just fine. I just serviced the original hubs on my road bike from 1995, and I'm not sure if the bearings were ever serviced before this, besides adjusting play. The cup and cone were both in good shape, the grease was dirty as hell and the bearing were all replaced, but a little degreasing then regreasing and it spun like a brand new wheel...

theoretically you can get way more junk caught up in there I guess, but it's not something I'd worry about.
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I suggest checking the post dates on the stuff you are commenting on. This is a 7 year old thread...
 
Scurvy092 said:
I suggest checking the post dates on the stuff you are commenting on. This is a 7 year old thread...
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I was hoping that something new has been produced since this thread was started. I guess next time I'll just start a new one.

Does the Kershaw Tilt have a ball bearing pivot?
 
I have a Woods bladeworks framelock with rollerbearings. it is smoother than all hell eve after 9 months of carry and no major cleaning of any form of disassembly.
 
Hypermole said:
I was hoping that something new has been produced since this thread was started. I guess next time I'll just start a new one.

Does the Kershaw Tilt have a ball bearing pivot?
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Yes, but it is a framelock...

There are a whole bunch of production knives with bearing pivots but they are all liner/frame locks

ZT has the 0560, 0600, 0777, 0801, 0888, 0454

Spyderco has the Southard and the Domino

CRKT has a bunch of IKBS knives. Ripple, Eros, etc etc etc
 
Seems you can't ever please everyone, people complain that they see the same posts every week and others complain when someone revives an old thread for new info.

As to the bearings it really depends on the design, your environment, and you. Someone mentioned bicycle hub open bearings but I've yet to see a quality bicycle hub or bottom bracket that used open, caged, or sealed ball bearings that didn't have seals/shields built into the design in some form to keep most of the crud out, at least the big gritty stuff. As a kid who learned the hard way not to ride his bike over the hubs and bottom bracket in silty river floodwater, if you get silt/sand/grit in bearings it will chew them up, period. The only way to avoid it is clean them regularly or seal them up one way or another so contamination doesn't get in there in the first place.

I can't comment on DR's design as I'm not intimately familiar with it. The only knife I have experience with that has bearings in the ZT 0561, it has no sealing, the balls are just caged in plastic and put in place of the washers with deeper cutouts in the blade/handle. I live in the desert and those days I'm in the field my knife is used a lot. If I do a week of field work that 0561 is begging to be cleaned, it's rough and gritty. For comparison most of my other washer pivot knives if I use a non-dirt attracting dry'ish lube it will do that duty for a couple months before needing a full tear down. Now if you work in an office, or even outside where there isn't a lot of fine dust or your knife spends most of it's time in your pocket while there, it's not a big deal. If you like tearing down your knife more frequently to clean/lube it then it's not a big deal either. For me if I go in the field that knife doesn't go anymore, because I don't like doing a full knife tear down every week.
 
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