Ceramic bearings

[Maprik]

Some people have contacted me about replacement ceramic bearings and while the idea of super hard bearings at first sounds appealing I don't think it's a good idea. I would rather have steel bearings wear out and replace those. The alternative is to have your ceramic bearings wear a groove into your handles if you don't have race washers that you can replace or wearing a groove into your blade. Either way, you're gonna get blade play that can't be easily fixed. As Peter Rassenti's repair guy I can say that he doesnt use any washers, the bearings run against the blade and the titanium of the integral handle. The bearings are easily replaced if they ever get worn out (not a repair I've had to do yet). Just $.02.

 

[Night Rider]

Very good point I hadn't thought of Maprik. Is there a site that one could order PB washers or bearings from? I've had no luck at the big box hardware stores in the past when looking for replacements.

 

[Maprik]

Ticonnector.com is one source I've used. USAknifemaker.com too.

Very good point I hadn't thought of Maprik. Is there a site that one could order PB washers or bearings from? I've had no luck at the big box hardware stores in the past when looking for replacements.

 

[Stumpy72]

Thanks for this insight. I was thinking about converting one of my flippers over to ceramic bearings, but that possible game plan just ceased to exist.

 

[91bravo]

I have a ceramic bearing in one of my Manix 2s and a silicon carbide one in another. No grooves worn into the tang of the blade, going on 2+ years of use now. Slick as butta!

 

[Maprik]

I have a ceramic bearing in one of my Manix 2s and a silicon carbide one in another. No grooves worn into the tang of the blade, going on 2+ years of use now. Slick as butta!

That's good. Heavy user? Liners holding up well too? Any wear?

 

[91bravo]

No wear that I can see. I flick them mindlessly sometimes and yes I use them weekly. I rotate all my knives so they all see some form of use. The SiC bearing feels like it runs on greased lightning! It could just be the variances between each knife, but my Manix with the SiC bearing feels slicker than the ceramic or steel ones.

 

[Maprik]

Well I guess my observation is based more on the theoretical than the observed when it comes to bearings. It may take years to notice any noticeable wear depending on usage. However, I've seen titanium wear amazingly quickly on lock faces subjected to daily use. Where there is friction there is wear. So my point is that I would rather have replaceable parts take the wear than non-replaceable parts.

 

[91bravo]

Maybe the coil spring on the Manix 2 doesn't apply a lot of pressure as say, tightening the pivot screw on a bearing system. The spring tension is constant on the Manix 2. I guess you can overtighten a pivot screw, and I could see how this would wear races into your liners or the actual blade itself.

 

[sharp_edge]

Some people have contacted me about replacement ceramic bearings and while the idea of super hard bearings at first sounds appealing I don't think it's a good idea. I would rather have steel bearings wear out and replace those. The alternative is to have your ceramic bearings wear a groove into your handles if you don't have race washers that you can replace or wearing a groove into your blade. Either way, you're gonna get blade play that can't be easily fixed. As Peter Rassenti's repair guy I can say that he doesnt use any washers, the bearings run against the blade and the titanium of the integral handle. The bearings are easily replaced if they ever get worn out (not a repair I've had to do yet). Just $.02.

I agree. I think ti framelock on bearings without a washer in between is a flawed design. I am gradually seeing the sign of off centering of the blade to the ti lock side on multiple knives that are just 2 or 3 years old (granted they have been flipped quite frequently). Swapping the bearings wont help. I think the deeper and deeper groove on the ti lock side is the reason.

 

[91bravo]

If you look hard, you can see the silicon carbide BB in between the handles. Notice what appears to be a race on the tang of the blade, but it goes away when I wipe it clean with a q-tip, so I don't think there's any kind of wear to that area. If there is, then it's very minimal and I don't foresee it being a problem.

It's a different dynamic of physics going on here as well. Coil spring wedges that silicon carbide BB between the tang of the blade and the backspacer of the knife. Totally different than over tightening a pivot with ceramic washer system in it.

 

[91bravo]

I agree. I think ti framelock on bearings without a washer in between is a flawed design. I am gradually seeing the sign of off centering of the blade to the ti lock side on multiple knives that are just 2 or 3 years old (granted they have been flipped quite frequently). Swapping the bearings wont help. I think the deeper and deeper groove on the ti lock side is the reason.

I've done this with my ZT0560 a few years back and I didn't even use ceramic caged bearings, just the factory blue ones. After a few years, there were some deep grooves in the handles, that also affected my blade centering.

 

[Mo2]

Ceramic doesn't rust like steel. So many use it due to this. Many use them cause it's popular. But always use hardened steel washers with ceramic. Ceramic pivot bearings don't change action at all. Generally a ceramic detent is idea for action though. If I have the choice I'd go all ceramic assuming they have hardened steel washers. Heck I prefer hardened steel washers on all bearing knives steel bearings or ceramic

 

[RBid]

I’m open to correction, so please correct me if I’m misunderstanding this...

iirc, ti frames are typically around high 40s hrc, blade steels are commonly 58-61 (maybe a point or two higher given a custom maker with a specific goal), and ceramic bearings are typically north of 75hrc. I’ve never heard a steel bearing number, but given flattening concerns, it would follow that they must come in a tick under the blade’s hardness, but harder than ti.

iirc, it’s also the case that ti and steel wear differently. Meaning, they exhibit different ways of wearing, even at similar relative hrcs. I believe I heard it said that ti will simply continue to wear at a pretty consistent rate, whereas steel will wear to a polish and then the rate of wear notably drops off.

If I am recalling that correctly, then steel washers between ti and bearings of any type would always be good, because the washers would take lifetimes to wear to the point of failure (assuming reasonable thickness), as opposed to a ti frame being destined to require care, regardless of bearing material.

It would also hold that, given those steel washers, ceramic bearings would be better than steel bearings in the long run. The idea would be that, once they worked a track into the washers, the rate of wear would come to a virtual standstill, and the bearings themselves would never exhibit wear.

This is a house of cards, based on whether I’m recalling things correctly. If I’m off base, please correct me.

 

[Maprik]

Very interesting observations and I agree that from a design standpoint, taking all of these factors into account, using ceramic bearings with hardened steel washers would be ideal. Allowing the bearings to wear a track into the washer, however, could cause blade play or misalignment. With the high tolerances so many knives have these days even a change in micrometers can throw a blade off center.

You've also made a strong case for why you can't just switch out your steel bearings for ceramic when you have a knife that does not use washers in its design. Ceramic bearings against Ti are going to wear out a groove eventually. So I should revise my op and not write off ceramic completely but advise that you consider your knife design before modifying.

 

[RBid]

Very interesting observations and I agree that from a design standpoint, taking all of these factors into account, using ceramic bearings with hardened steel washers would be ideal. You've also made a strong case for why you can't just switch out your steel bearings for ceramic when you have a knife that does not use washers in its design. Ceramic washers against Ti are going to wear out a groove eventually. So I should revise my op and not write off ceramic completely but advise that you consider your knife design before modifying.

If I’m remembering all of that right, your conclusion would be sound. I’d be curious if the even larger gap in hrc from ti to ceramic accelerated the rate of wear, or if steel bearings were already enough harder than the ti that it’s all the same. No idea how that plays out.

Hmmmm... @DeadboxHero help set me straight?

 

[Mo2]

Allowing the bearings to wear a track into the washer

This is the break in process for bearing knives. Once worn in they are pretty much set. Steel just takes longer to wear in a race. While ceramic is harder and wears tge races in faster. Nothing is getting misaligned.

This is well known to makers. At least the good ones. There's a point where they can't wear further due to its design and tolerances.

The problem with bear ti is that when prying with bearing knives etc the bearings of either materials digs gouges into the ti. This doesn't happen when operating a knife for cutting and slicing... Ie it's intended purpose

 

[marthinus]

The problem with bear ti is that when prying with bearing knives etc the bearings of either materials digs gouges into the ti. This doesn't happen when operating a knife for cutting and slicing... Ie it's intended purpose

Here were some tests done. Single ball bearings required 50kg or 110 lbs of sideways loading for deformation to take place in the Ti.

Meanwhile in Russia…

Hi everyone!

Last week I had an awesome opportunity to visit Shirogorov Brothers Workshop, during the talks about knives, production and knife industry development we came up with an idea to test bearings system used in Shirogorov knives in order to determine clear the advantages of specific bearing systems. I’m glad that I can share the results with the community now.
We selected Flipper 95 as a most popular model and the following bearing system were tested:

- Single-row ball bearing system - SRBBS (Serial Division F95), 17 balls on each side between blade and Ti scales.

- Single-row roller bearing system – SRRBS (Custom Division F95), 17 rollers on each side between blade and Ti scales, without hardened steel washers in Ti plates.

- Double-row roller bearing system - DRRBS (Sergey Shirogorov Custom F95), 27 rollers on each side between blade and Ti scales, with hardened steel washers in Ti plates.

The testing was rather simple and pragmatical – we applied a vertical load* directly to the pivot point of the knife resting on two wooden bars so that the pivot had no support. Load was applied progressively to the certain magnitude, then knife was checked for damages sustained, residual deformations to the parts, changes in the mechanics of the locking and flip.
*all the figures are given both in kilos and lbs.

1. Single-row ball bearing system - SRBBS
- 30 kg / 66 lbs – no changes to the mechanics, no deformations;
- 50 kg / 110 lbs - no changes to the mechanics, blade is centered, no blade play, no visual defects. After the knife was taken apart tiny deformation on the titanium plate made by steel ball of the bearings observed (see on the pic. in black);
- 70 kg / 154 lbs – notable changes in the mechanics when deploying the blade slowly without applying the flip, still no blade play, stronger deformations on the titanium plate observed (see on the pic. in red).

2. Single-row roller bearing system – SRRBS
- 75 kg / 165 lbs – no changes to the mechanics, blade is centered, no blade play, no visual defects. After the knife was taken apart slightly noticeable deformation on the titanium plate made by steel rollers of the bearings observed (see on the pic. in black);
- 100 kg / 220 lbs – no blade play, blade is still perfectly centered, barely audible changes in the mechanics and more noticeable deformations on the titanium plate observed (see on the pic. in red).

3. Double-row roller bearing system - DRRBS
- 60 kg / 132 lbs - no changes to the mechanics, blade is centered, no blade play, no visual defects.
- 100 kg / 220 lbs – no changes to the mechanics, blade is still perfectly centered, no blade play, no residual deformations, no alien sounds in the mechanics work.

For better appreciation of the pressure knives withstood, we shot several pictures of the knife bending under the load for Sergey Shirogorov custom Flipper 95 (S90V, 3,5 mm thick spine, DRRBS):

0 kg / lbs

50 kg / 110 lbs

80 kg / 176 lbs

100 kg / 220 lbs

Here is also a video spot (in Russian only unfortunately, just hope that you can get the general idea of the test from it). And sorry for bad focusing, it was the first time we shot video with this camera.

[video=youtube;UyLudvm3sKY]

All the best and a sharp edge,
Dmitry

 

[007Airman]

I’m open to correction, so please correct me if I’m misunderstanding this...

iirc, ti frames are typically around high 40s hrc, blade steels are commonly 58-61 (maybe a point or two higher given a custom maker with a specific goal), and ceramic bearings are typically north of 75hrc. I’ve never heard a steel bearing number, but given flattening concerns, it would follow that they must come in a tick under the blade’s hardness, but harder than ti.

iirc, it’s also the case that ti and steel wear differently. Meaning, they exhibit different ways of wearing, even at similar relative hrcs. I believe I heard it said that ti will simply continue to wear at a pretty consistent rate, whereas steel will wear to a polish and then the rate of wear notably drops off.

If I am recalling that correctly, then steel washers between ti and bearings of any type would always be good, because the washers would take lifetimes to wear to the point of failure (assuming reasonable thickness), as opposed to a ti frame being destined to require care, regardless of bearing material.

It would also hold that, given those steel washers, ceramic bearings would be better than steel bearings in the long run. The idea would be that, once they worked a track into the washers, the rate of wear would come to a virtual standstill, and the bearings themselves would never exhibit wear.

This is a house of cards, based on whether I’m recalling things correctly. If I’m off base, please correct me.

Lot of good info and also a good reason not to use ceramic in the lockface.

 

[Mo2]

Here were some tests done. Single ball bearings required 50kg or 110 lbs of sideways loading for deformation to take place in the Ti.

Yes I've seen the thread many times. I've also seen it elsewhere online with other people's knives. It's not too common but does happen. Usually when people over tighten the pivot screw