When shopping online for bearings, how do you decide on QUALITY?

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On Fri, 07 Jun 2013 22:49:12 -0700, DD_BobK wrote:

I'm leaning toward a mix of that from you & that from dpb, which is to buy the cheapest reliable brand-name bearings.
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wrote:

After over 45 years of buying parts for all kinds of machinery I have developed a tactic that works well for me. Never buy the cheapest or the most expensive unless you have fewer than 3 options.
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On Fri, 07 Jun 2013 22:49:12 -0700, DD_BobK wrote:

My comment "I just buy the cheapest ones... cuz price the only thing that matters."
.... was facetious.
When I buy bearings...
I apply "Cost of quality vs cost of non-conformance."
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On Sat, 08 Jun 2013 20:59:08 -0700, DD_BobK wrote:

You will recall, the question is how to decide on QUALITY bearings.
So far, the ABEC/ISO rating of either ABEC1/P0 or ABEC3/P6 seems to be a good aiming point for *tolerance*; but that says nothing about materials.
In addition, there appears to be a radial play standard, which specifies the internal clearances (e.g., the metric standard for deep-groove bearings C3 or NPB Code inch standard P25). http://www.astbearings.com/ball-bearings-radial-play.html
The problem, of course, is obtaining this information. Luckily some supply houses specify both the tolerance & radial play:

The steel to aim for should be at least SAE 52100 chromed steel, which is a through hardening, fine grain, Martensitic steel, although a variety of stainless steels is an option (as are ceramics, but not typically for a pool pump motor bearing).
Note that most stainless steel bearings will still rust, and, that SKF says they have a lower load capacity; so, I'm not going to aim for stainless steel materials.
It seems buna-N rubber seals are a fine material for pool pump applications, although Viton is available.
And, it might be important in some applications to have a H1 NSF Certified food grade grease, but not in mine (SKF uses the suffix VT378 for such bearings).
http://www.skf.com/group/products/bearings-units-housings/ball-bearings/deep-groove-ball-bearings/stainless-steel-deep-groove-ball-bearings/index.html http://www.abbottball.com/materials/stainless-steel-balls-302.php
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One useful definition of "Quality" is "fitness for use".
Now that you've read a bit about bearing design & bearing materials....you're a bearing expert too?
omg.....
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On Sun, 09 Jun 2013 22:08:51 -0700, DD_BobK wrote:

Indeed. You are a wise soul.
For example, it turns out that the 25-inch diameter "cord" ring around the Sta-Rite System 3 Model S8M150 filter tank is an odd "Alladin" size of "Alladin O-486".
Upon first inspection, this looks like a standard o-ring trade size; but there is no o-486 in the standard inch-size charts! http://www.oringwarehouse.com/
A typical buyer would shell out $27 to $40 for the Sta-Rite / Pentair part number 24850-0009, which is what the market will bear: $27 http://www.theoringstore.com/index.php?main_page=product_info&cPath36&products_id 551 $33 (Amazon.com product link shortened) $35 http://www.poolsupplyworld.com/Pentair-24850-0009-O-Ring-S8S70/24850-0009.htm $40 http://www.yourpoolhq.com/sta-rite-24850-0009-system-3-tank-o-ring.html
However, for me, bulk cord glued together is "fit for this use", as long as the price for materials is well below those numbers above.h
It may not work, but, it seems to me that for a buna-N material, your basic 100 viscosity cyanoacrylate adhesive should serve well as an O-ring Glue (applied sparingly due to the sheer strength of this particular style of glue).
So, my initial plans are to make my own 25-inch diameter o-rings from bulk cord stock, if I can get the stock for about $1 to $2 a foot. http://www.theoringstore.com/index.php?main_page=index&cPath 7
If I can't get the stock at that price, I'll buy the Buna-N 70 durometer o-rings for about $30. The decision is all about quality & fitness for use, against the classic cost tradeoffs.
Just like you advised.
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BIG SNIP

as long as the price for materials is well below those numbers above<<<<

use, against the classic cost tradeoffs. <<<<
Hmmm... signs of learning, might there be hope?
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SNIP

for - you get what the market will bear - and the market is filled with idiots as well as savants)<<<
More wisdom from DADD ...or perhaps his father?
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On 6/7/13 11:33 AM, Danny D wrote:

Have you wandered down to the local auto parts store?
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On Sat, 08 Jun 2013 22:24:13 -0500, Dean Hoffman wrote:

That may be a great idea!
Now that I know to aim for a 52100 chromed steel bearing with a Buna-N contact seal with no shields and with an ABEC3/P6 tolerance rating meeting P25/C3 radial play standards ... I can go *anywhere* to buy the right bearing.
So, now that I know how to decide on QUALITY, I *can* shop at a local auto-parts store.
I had not *thought* about auto parts stores prior though; so I will call a few up tomorrow when they open to see if/how they sell bearings.
I would think they'd only carry those rated for automotive applications - so - the ratings & materials will be what matters.
Thanks for the suggestion.
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In my views you should refer the reviews for the customers or you can contact them and confirm.
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