Roller skate bearings.

[David JuppParticipant @davidjupp51506]

"ABEC 11" is a branding. The ABEC scale stops a 9.

I'd have thought the clearance (often shown with C and a digit) of the bearing might be as least as important as the tolerance rating, though there will be some inter-relation, difficult to get super tight clearances if the tolerance limit for the parts is wide.

[noel shelleyParticipant @noelshelley55608]

Your right David, for electric motors C3 is often the fit. Noel.

[Robin GrahamParticipant @robingraham42208]

Thanks for replies,which reinforce my gut feeling that the benefit of these super-expensive bearings is largely, or perhaps wholly, psychological.

As far as I can gather the ABEC specs relate to the tolerances on the inner and outer diameters of the bearings. My daughter pressed her bearings into the plastic wheels by hand then mounted them on to the nominally 8mm axles. She is a slightly built woman, so I doubt that she would have been able to achieve the force necessary to get a tight interference fit to the axle – which is essential to prevent 'creep', when there is movement between the inner race and the axle which can lead to abrasion. And what is the tolerance on the axle diameter I wonder!

MichaelG thought the claim on the Slick Willies website:

[quote]

When you get dirt into your Ceramic Reds, the ceramic balls will help to re-polish the steel races flat again, providing a self-healing benefit because ceramic balls are so much harder than steel.

[/quote]

was 'questionable'. I think that is a characteristically polite way of saying 'wrong' whilst admitting the possibility of error.

I had a look at the SKF website and they go into all this in mind boggling detail – it's pretty complicated. More than I can cope with at the moment, but enough to convince me that the claims made by the skate people are – well – questionable.

It's just marketing nonsense isn't it?

Robin.

 

Edited By Robin Graham on 14/02/2021 02:35:26

Edited By Robin Graham on 14/02/2021 02:36:17

[Bill PudneyParticipant @billpudney37759]

I know it's different applications, but………….. When I used to be responsible for machine tool specification and acquisition, I was given the following advice. Ceramic spindle bearings are fine in an environment where there will be no machine "crashes", this would apply to a production environment where all tooling, hard and soft, all processes etc are proven. However in a "jobbing" environment where the frequency of new tasks with unproven tooling will be far higher, then ceramic bearings are not advised. Simply because they have a very low tolerance for shock. In a jobbing environment steel bearings are advised.

This recommendation was to avoid the wrecking of machine tool spindles, which at the time, 15 or so years ago varied in cost between AU$10,000 for a Bridgeport VMC to over AU$40,000 for a Makino horizontal mill.

Now I'm not sure of the likelihood of shock loadings on skates, but I would imagine that they are fairly high. I'm also not sure of the relative cost of steel bearings vs ceramic bearings, and the cost of changing knackered bearings for good ones. However they are probably things which should be considered.

No doubt someone will shoot me down in flames with …"I've had ceramic bearings on my skates, skate board, in lines for the last 20 years, skated around the World, up mountains across rivers, across the Sahara, never had a problem" To which my response would be " Well done"

cheers

Bill

[GeorgineerParticipant @georgineer]

Posted by SillyOldDuffer on 13/02/2021 10:27:19:

Much of this is psychology… A product's purpose may making someone happy, not providing the most economic answer. If a hi-fi aficionado believes gold-plated speaker wire makes Jazz sound better, why not feed our children by making him what he wants? And if applying a massive mark-up to our dodgy cable 'proves' it's superb, who are we to disagree? Everyone is happy – his musical experience is enhanced because he believes it sounds better, and we've earned a crust.

Absolutely. Two friends of mine set up a hi-fi company in the seventies using direct-drive speakers which I understand was ground-breaking stuff at the time. Listening to direct-cut discs (who remembers them?) through their equipment was a revelation. They marketed it at cost plus a sensible mark-up and sales were very poor. They then added some bullshine to the marketing and raised their price above the conventional competition and sales took off. It had as much to do with the customer's bragging rights as the quality of the sound.

George B.

[jaCK HobsonParticipant @jackhobson50760]

The big boy bearing manufacturers like FAG and SKF make top quality and probably can't be bettered. I suspect anything above their prices is to cover extra marketing.

But the £200 are super accurate ceramic balls – not easy to make I suspect, and so you are getting something for your money. You might not need that something. I wonder who actually makes them, and for what purpose?

I just got set of 8 ABEC-9 from amazon because it was cheaper than buying 2 of the cheapest from BearingBoys (after delivery costs, 'casue I got Prime)

And there is a big difference in quality, longevity between cheapest and good SKF/FAG. I use skateboard wheels on my belt grinder and cheap lasts tens of hours; expensive… I haven't worn them out yet (probably mostly due to the quality of the seals).

 

I bet the 8mm version of these will make the £200 ones look cheap.

https://www.bearingboys.co.uk/SKF-High-Temperature/62012ZVA228-SKF-High-Temperature-Ball-Bearing-12mm-x-32mm-x-10mm-92754-p

 

Or even 8 of these is going to set you back 

£427.20

https://simplybearings.co.uk/shop/p17720/SKF-6082RSLTN9HC5C3WTF1-Ceramic-Hybrid-Ball-Bearing-with-SiN4-Balls-and-Two-Low-Friction-Seals-8x22x7mm/product_info.html?backstep=1

 

Edited By jaCK Hobson on 14/02/2021 16:59:23

Edited By jaCK Hobson on 14/02/2021 17:00:32

Edited By jaCK Hobson on 14/02/2021 17:07:11

Edited By jaCK Hobson on 14/02/2021 17:20:28

[John O’ReillyParticipant @johnoreilly65187]

Being a past roller blade enthusiast heres my two cents. The ABEC rating when it comes down to it effects the free rolling speed on those wheels. I had ABEC 3 bearings in my blades and when I changed them out to ABEC 7 I nearly fell on my ass they were so free rolling. The tighter precision effects the speed you are able to attain. Makes it a little more unstable then the slower more steady ABEC3 bearings.

Johnny O

[bernard towersParticipant @bernardtowers37738]

Surely ceramic ball races were originally introduced for gas turbines as the hey coped with the dirty atmosphere that the engine breathed. Ceramic balls crush the foreign bodies where steel balls skid.

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