Double-row bearings - anyone know where to get them?

If the longer (slower) shipping isn't too outrageous (cost?), I'd be happy (and appreciative) to buy from 2 to 10 sets of 2 disks each (4 to 20 MRBS disks total)? Does that sound reasonable to you? If it is asking too much (for the higher quantity) just let me know. I am very flexible on the number of disks. For me they'd be just extra parts I'd like to have around. I'm not a knife maker or in a huge rush...but do think it's very cool of you to offer to take on this little project! My thanks in advance hankjiang1. To email me directly - mister maui @ earthlink.net (remove the spaces of course)
 
Pittknife said:
but honestly the extra rows do not make a difference. It's all about the smoothness of your counterbore, smoothness on your blade flat, lock geometry & pressure and finally your detent. Ceramic detent ball will make your knife much smoother than multi row bearings because that is what is dragging across the blade face.
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I agree.

I'm trying to figure out the benefits (if any?) to having another row of bearings? The only thing I can see it doing is adding more contacted surface area (i.e. friction) and if anything, slowing the blade down.

I suppose it might add the VERY slightest amount of rigidity against any lateral blade play, but honestly, it would likely be negligible, and if your knife is machined properly, is unnecessary.

Seems more like a marketing gimmick than anything, though I'd love to hear an advantage I'm not thinking of or understanding.

Right now I just see a more expensive, less efficient bearing that takes longer to ship?
 
Scrim said:
If the longer (slower) shipping isn't too outrageous (cost?), I'd be happy (and appreciative) to buy from 2 to 10 sets of 2 disks each (4 to 20 MRBS disks total)? Does that sound reasonable to you? If it is asking too much (for the higher quantity) just let me know. I am very flexible on the number of disks. For me they'd be just extra parts I'd like to have around. I'm not a knife maker or in a huge rush...but do think it's very cool of you to offer to take on this little project! My thanks in advance hankjiang1. To email me directly - mister maui @ earthlink.net (remove the spaces of course)
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I think its better to buy a couple first.

I can order a few bearings and ship to you with the slow carrier, once you receive you can then decide whether to buy more.
 
Sounds good. I have about a dozen knives with these exact same sets of MRBS disks in them, so I know that they are good replacement parts to have (for me). Let me know the details whenever you are ready to.
 
knife to a gunfight said:
I agree.

I'm trying to figure out the benefits (if any?) to having another row of bearings? The only thing I can see it doing is adding more contacted surface area (i.e. friction) and if anything, slowing the blade down.

I suppose it might add the VERY slightest amount of rigidity against any lateral blade play, but honestly, it would likely be negligible, and if your knife is machined properly, is unnecessary.

Seems more like a marketing gimmick than anything, though I'd love to hear an advantage I'm not thinking of or understanding.

Right now I just see a more expensive, less efficient bearing that takes longer to ship?
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They're just better at spreading out heavy loads and reducing the chance of damage with a high amount of sideways force to a blade. In the case of these you have 16 contact points instead of eight, and the outer row is simply farther from the pivot which reduces the force it would take with given torque on the blade. in theory you could say there is more friction, but in my experience this is negligible. And anyways, once you get to a certain amount of freeness with bearings it's the detent ball that causes most of the friction when opening/closing a knife anyways.
 
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Scrim said:
Sounds good. I have about a dozen knives with these exact same sets of MRBS disks in them, so I know that they are good replacement parts to have (for me). Let me know the details whenever you are ready to.
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I expect to have the bearings in my hands by Feb 16th, I'll email you by then. Does your email include mister ?
 
Sounds great! And yes, it does (my email)--> mister maui @ earthlink . net (just remove all the spaces). :)
 
From an engineering point of view, what purpose does the inner row serve? They would add drag but have little effect on load bearing? It isn't a straight thrust application where adding elements adds capacity, the real load is torque (when the blade has a side load) where one side of the bearing is loaded and the other side is unloaded and anything in-between would also be largely unloaded and not doing anything. Am I missing something? In this application, wouldn't the inner row be superfluous?
 
hankjiang1 - Just to mention it again, please let me know what the costs will be, especially shipping. What I don't want is to have to pay something like $30 US to ship 2 or 4 ($5 worth of) tiny bearing disks. If the shipping cost is high, I'd want to get more disks in the shipment to make it worth the shipping costs. (plus some profit for you!) Thanks again!:)
 
Scrim said:
hankjiang1 - Just to mention it again, please let me know what the costs will be, especially shipping. What I don't want is to have to pay something like $30 US to ship 2 or 4 ($5 worth of) tiny bearing disks. If the shipping cost is high, I'd want to get more disks in the shipment to make it worth the shipping costs. (plus some profit for you!) Thanks again!:)
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Don't worry, it should be only a few bucks in total, I'll cover it. Just a fellow knife junkie helping out another.
 
Hank, This is extremely cool and generous. I will owe you one! Please let me know how I will able to reciprocate. I sent you a direct email but wanted to also thank you here on bladeforums. I'll look forward to this whenever you can get to it. No rush. VERY much appreciated. It is a truly kind gesture. Let's stay in touch by email. But again, my sincere thanks in advance!
 
Nathan the Machinist said:
From an engineering point of view, what purpose does the inner row serve? They would add drag but have little effect on load bearing? It isn't a straight thrust application where adding elements adds capacity, the real load is torque (when the blade has a side load) where one side of the bearing is loaded and the other side is unloaded and anything in-between would also be largely unloaded and not doing anything. Am I missing something? In this application, wouldn't the inner row be superfluous?
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I get your point. Theoretically the outer row should be doing all the work, but this is based on the assumption of no deforming on the handle side where it contacts the bearing.

With that assumption, the contact face between handle and bearing will be dots of the bearing balls, so the area of contact face will be zero, which makes pressure infinite big.

So in real case either side or both sides will deform, since the bearing balls are ceramic I believe it's the handle that deforms, being cut little grooves to present face contact. With an extra row to share the force it should make the groove shallower, but also an extra groove.

So which one is better? I don't know since I'm not capable of performing a through modeling&calculation. I think it's better to do some real experiments and screw the theories. We are knife makers.
 
hankjiang1 said:
I get your point. Theoretically the outer row should be doing all the work, but this is based on the assumption of no deforming on the handle side where it contacts the bearing.

With that assumption, the contact face between handle and bearing will be dots of the bearing balls, so the area of contact face will be zero, which makes pressure infinite big.

So in real case either side or both sides will deform, since the bearing balls are ceramic I believe it's the handle that deforms, being cut little grooves to present face contact. With an extra row to share the force it should make the groove shallower, but also an extra groove.

So which one is better? I don't know since I'm not capable of performing a through modeling&calculation. I think it's better to do some real experiments and screw the theories. We are knife makers.
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True, the outer ring is taking most of the force. The inner ring is there because there is space for it and no reason not to have it. It doesn't take as much load but it still takes some.
I am saying this from my engineering and physics knowledge, but if you want real world tests Shirogorov did some and found with their single row ball bearings that side loads didn't affect performance at all until about 110lbs, and with roller bearings until 220lbs. I would rather have roller bearings for this strength advantage but the only ones I have found are too big, so double row roller bearings are the next step down.
 
Scrim said:
Hank, This is extremely cool and generous. I will owe you one! Please let me know how I will able to reciprocate. I sent you a direct email but wanted to also thank you here on bladeforums. I'll look forward to this whenever you can get to it. No rush. VERY much appreciated. It is a truly kind gesture. Let's stay in touch by email. But again, my sincere thanks in advance!
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Nice to know that I hooked someone up with what I was looking for. I don't need anything right now but when I do at least I know who to talk to.
 
Thank you for your kind words Scrim and Atakdog, I learned a lot from this forum, this is the least I can do to repay you guys.

I'll post the specific measurements for your reference when I have it.
 
hankjiang1 said:
Thank you for your kind words Scrim and Atakdog, I learned a lot from this forum, this is the least I can do to repay you guys.

I'll post the specific measurements for your reference when I have it.
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Gong xi fa cai hank!

Really cool how you helped out fellow knife nuts here on bf.
 
benzology said:
Gong xi fa cai hank!

Really cool how you helped out fellow knife nuts here on bf.
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Thanks benzology, that's a sweet greeting.

I just received the bearings, the dimensions are as following,

Ball diameter - 1.588mm (1/16')
Ball material - ceramic
Cage OD - 13.47mm
Cage ID - approximately 6.1mm
Cage thickness - 1.03mm
Cage material - plastic
Inner row diameter - approximately 9mm
Outer row diameter - approximately 11.5mm

I would like to post a picture but don't know how. Anyway I'm shipping it today, hope it will be useful to Scrim.
 
Hank, This is very nice of you. Please think of a way I can return the favor!! I will post here and contact you once they arrive. I will also take photos of one (or maybe more) of my clones that (I will disassemble AND I suspect) use these MRBS bearing disks and verify that the ones you sent are in fact the same (or a different diameter) than the ones used in these popular MRBS clones and Kevin John "original designs" that I own...only because I think it will be interesting for members on this thread to see. I will then post photos of my findings, in this thread. I thank you again, in advance, so very much for this kind gesture, Hank.:thumbup:

In the mean time, here is a photo of my disassembled CKF Suhkoi...which I suspect is using the same MRBS disk...
 
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