Roller pivots on production knives

[raymond454]

Are there any production knife companies the utilize ball bearings such as the IKBS system on their knives? Would you pay more for a ZT or Benchmade if they offered some models that used rollers?

 

[Lapedog]

Are there any production knife companies the utilize ball bearings such as the IKBS system on their knives? Would you pay more for a ZT or Benchmade if they offered some models that used rollers?

Lots of production knives use the IKBS. Boker Kwaiken, and HTM Bullwhip for example.

Btw IKBS isn’t a roller bearing system. Roller bearings aren’t ball bearings.

The only production knife I can think of that uses roller bearings is the Real Steel Megalodon, the newer version. Some older Shirogorovs did too.

These are roller bearings.

 

[b00n]

Mhh, I didn't know the Megalodon had them, I might need one just for novelty sake now.

 

[Lapedog]

Mhh, I didn't know the Megalodon had them, I might need one just for novelty sake now.

The newest version has them on the full ti framelock. I am not sure about the liner lock or the “megalodon eclipse” which is the framelock with composite front scale.

I got a megalodon in a trade and my friend liked it so much he had to have it. It is an outstanding knife. Buy with confidence.

 

[b00n]

The newest version has them on the full ti framelock. I am not sure about the liner lock or the “megalodon eclipse” which is the framelock with composite front scale.

I got a megalodon in a trade and my friend liked it so much he had to have it. It is an outstanding knife. Buy with confidence.

The 2018 Meg Eclipse CF is listed with needle bearings, so same system.

 

[Wowbagger]

That is so cool; in an industrial built like a tank sort of way.
Even with super thin lube I imagine it doesn't win any gravity drop contests but I'm glad they made them and they are out there.

Especially when dirty; oh my gosh!
Do these have seals or are they just open ?

Another question : does anyone make a cup and cone bearinged knife or is every thing just a thrust bearing arrangement ?

 

[AF]

So how do rollers compare to ball bearings? I assume they're more expensive. What makes them better (or worse)?

 

[b00n]

So how do rollers compare to ball bearings? I assume they're more expensive. What makes them better (or worse)?

More surface/contact area so more stable and thinner profile/height. In turn they don't like force applied in the wrong direction (IE side to side force) and they aren't good for high RPM applications in an industrial setting, although I think in the knife application it'd be negligible.

 

[AF]

More surface/contact area so more stable and thinner profile/height. In turn they don't like force applied in the wrong direction (IE side to side force) and they aren't good for high RPM applications in an industrial setting, although I think in the knife application it'd be negligible.

Thanks. I guess the greater contact area means more friction compared to ball bearings?

 

[b00n]

Thanks. I guess the greater contact area means more friction compared to ball bearings?

Yeah, more friction and in turn create more heat. We have electric drills at work that run at ~35k RPM (and Pneumatic ones that run at 15 - 20k) it makes a difference there, but in a knife flipping out not so much.

 

[Lapedog]

That is so cool; in an industrial built like a tank sort of way.
Even with super thin lube I imagine it doesn't win any gravity drop contests but I'm glad they made them and they are out there.

Especially when dirty; oh my gosh!
Do these have seals or are they just open ?

Another question : does anyone make a cup and cone bearinged knife or is every thing just a thrust bearing arrangement ?

Honestly I have some theoretical gripes about roller pin bearings. I think they are better in this type of application.

When they are laying flat in circle like on those knife pivots part of the bearing has to be dragging. The outside of the circle farthest from the pivot has to move faster to cover the same degrees of rotation as the inside of the circle closest to the pivot.

Of course this is all theoretical as infact the roller pin bearings seem to work quite well.

Infact I wonder about even ball bearings because if the side of the ball touching the blade is rolling one direction in order to get maximum freeness the opposite side of the bb touching the inside of the scale would have to be rolling in the opposite direction.

As in when I roll a ball away from me the top of the ball is moving away from me but the bottom of the ball is moving towards me. With bbs in knife pivots it seems like one side of the bb will have to be dragging against one of the surfaces, tang or inside of scale.

 

[Lapedog]

Yeah, more friction and in turn create more heat. We have electric drills at work that run at ~35k RPM (and Pneumatic ones that run at 15 - 20k) it makes a difference there, but in a knife flipping out not so much.

But the less contact area the greater force is being applied to the area of contact. If I have a pivot with 6 bearings per side the force of the liners pressing against the bearings is divided by six assuming equal distribution. If I have 12 bearings per side then that force is divided by 12.

 

[sharp_edge]

Yeah, more friction and in turn create more heat. We have electric drills at work that run at ~35k RPM (and Pneumatic ones that run at 15 - 20k) it makes a difference there, but in a knife flipping out not so much.

I think I understand your explanation. Does it mean, everything the same, a knife with ball bearings should be smoother than with roller bearings?

 

[Justin Partridge]

The newest version has them on the full ti framelock. I am not sure about the liner lock or the “megalodon eclipse” which is the framelock with composite front scale.

I got a megalodon in a trade and my friend liked it so much he had to have it. It is an outstanding knife. Buy with confidence.

Just FYI, not all real steel megeladons have the needle bearings. I have a 2017 full titanium one and it has ball bearings. It is still very smooth but I was kind of disappointed.

 

[Wowbagger]

Yeah, more friction and in turn create more heat. We have electric drills at work that run at ~35k RPM (and Pneumatic ones that run at 15 - 20k

Is that reversed? Usually air is faster. At least as far as grinders. What do I know; in my world 3K is fast for a drill bit.

 

[b00n]

Is that reversed? Usually air is faster. At least as far as grinders. What do I know; in my world 3K is fast for a drill bit.

No, not reversed, the air ones can go faster, but we don't run them as fast. At full power I think the pneumatic ones can handle ~40k if I am not mistaken. (I'll check tomorrow, I don't like putting out vague info.) I can post some pictures of the "drill bit" too, basically just two small spinning blades.

 

[b00n]

I think I understand your explanation. Does it mean, everything the same, a knife with ball bearings should be smoother than with roller bearings?

It should be smoother on ball bearings, or at least faster deployment, the roller/needle bearings would mainly provide lateral/side to side support. shinyedges , being a machinist/CNC programmer might have a bit more detailed insight.

 

[Glenn Goodlett]

As in when I roll a ball away from me the top of the ball is moving away from me but the bottom of the ball is moving towards me. With bbs in knife pivots it seems like one side of the bb will have to be dragging against one of the surfaces, tang or inside of scale.

Say again. This does not make sense to me.

I understand the idea of roller bearings looseing some efficiency when lined up radially. Ideally, they could use tapered rollers with tapered races.

 

[DocJD]

So how do rollers compare to ball bearings? I assume they're more expensive. What makes them better (or worse)?

Some cheap and junky knives have rollers :

 

[shinyedges]

It should be smoother on ball bearings, or at least faster deployment, the roller/needle bearings would mainly provide lateral/side to side support. shinyedges , being a machinist/CNC programmer might have a bit more detailed insight.

While I'm not a mechanical engineer, I agree the advantage to rollers is lateral support. The drag created by the distance the roller is from the pivot would be imperceptible, or so I would imagine.