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

[DD_BobK]

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."

[Danny D]

Thanks for those stories of experience. They were helpful, especially as I have *never* bought from Ebay and have only bought kid's toys and books from Amazon which were out of stock (and style) so they weren't in the brick & mortar stores or web sites.

I do believe you *never* get what you pay for and I hate hearing that statement because it ignores reality. Clearly Sears is selling that same pump seal (marketed by the Sta-Rite/Pentair part number) for about $75 when it just as clearly sells for about $10 online and both are from US Seal, a brand name.

Similarly, you can easily buy a Pentair U9-228A seal plate housing o-ring at the deeply discounted sales price of $15.85

Or, you can buy that very same o-ring for $1 at the recommended O-rings USA web site:

Is the $15.85 discounted o-ring (regular price is $24.85) *really* better simply because you paid so very much more for it?

Likewise, the $19 bearing at the pool supply house, marketing as being from "AO Smith" (whom, I've called, and they told me they buy *all* their bearings from NSK), is the same bearing you can buy easily for half to 1/3 of that anywhere online.

So, you never get what you pay for. You simply get what others pay for, as you alone cannot influence such pricing decisions.

Yet, as your stories show, the $2 bearings are the ones that, while intriguing, are almost too cheap to be believed. I don't know how much it costs to build a bearing, but whatever it is must be close to that price range, so to get that price without quantity caused immediate FUD in my mind (hence why I asked here).

As DDBK said, the risk might be too great for critical applications. I'm going to stick with the NSK bearings (or other reliable brand) from a reliable supplier, which means I'll be paying about $5 to $10 per bearing.

[Danny D]

Hmmmmmmmm.... I'll google for "bearing supply house in San Jose Ca". Surprisingly (for me), there were quite a few!

etc.

[Danny D]

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).

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).

[Danny D]

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.

[DD_BobK]

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.....

[DD_BobK]

HUGE SNIP

that statement because it ignores reality.

[Danny D]

Your wise words ring well and true.

For example, after researching o-rings and seals, I was able to source every seal and o-ring in each pool pump for less than $12 per pump (exclusive of tax & shipping).

Better yet, it would only have been about $7 in toto, had I opted for standard Buna-N seals, instead of the Viton seals.

Sta-Rite Max-e-glas II Pool Pump

1. .95 Shaft seal, Viton, PN 37400-0028S, PS3868
2. 1. $9.95 Shaft seal, Viton, PN 37400-0028S, PS3868 2. $0.16 Seal plate housing o-ring, U9-228A; O-240 Buna-N 70 Duro 3. $0.03 Trap cover o-ring, U9-375; O-12 Buna-N 70 Duro 4. $0.08 Drain plug o-ring (x2) U9-359; O-39 Buna-N 70 Duro 5. $1.41 Diffuser o-ring, U9-374; Alladin O-83 Buna-N 70 Duro.16 Seal plate housing o-ring, U9-228A; O-240 Buna-N 70 Duro
3. 1. $9.95 Shaft seal, Viton, PN 37400-0028S, PS3868 2. $0.16 Seal plate housing o-ring, U9-228A; O-240 Buna-N 70 Duro 3. $0.03 Trap cover o-ring, U9-375; O-12 Buna-N 70 Duro 4. $0.08 Drain plug o-ring (x2) U9-359; O-39 Buna-N 70 Duro 5. $1.41 Diffuser o-ring, U9-374; Alladin O-83 Buna-N 70 Duro.03 Trap cover o-ring, U9-375; O-12 Buna-N 70 Duro
4. 1. $9.95 Shaft seal, Viton, PN 37400-0028S, PS3868 2. $0.16 Seal plate housing o-ring, U9-228A; O-240 Buna-N 70 Duro 3. $0.03 Trap cover o-ring, U9-375; O-12 Buna-N 70 Duro 4. $0.08 Drain plug o-ring (x2) U9-359; O-39 Buna-N 70 Duro 5. $1.41 Diffuser o-ring, U9-374; Alladin O-83 Buna-N 70 Duro.08 Drain plug o-ring (x2) U9-359; O-39 Buna-N 70 Duro
5. .41 Diffuser o-ring, U9-374; Alladin O-83 Buna-N 70 Duro

Notice that the total cost of all the o-rings was about $2, sourced by trade size (with most of that cost being the one o-ring that was a non-standard trade size, as there is no "Alladin O-83" that I can find in any of the standard-inch-sized o-ring tables: a.

b. c.

Even so, and to the point of *you never get what you pay for*, (unless you know and think about what you're doing), just one of those o-rings could easily be sold to an unsuspecting consumer at a pool store for just about what I paid for the entire set!

The point is that anyone who says "you get what you pay for" is generally thinking *only* about price; and that is a mistake.

The real trick is in understanding what you're buying, and then understanding the market that is selling what you're buying.

Thanks to all you guys, I have a much better handle on the o-ring and pump-seal market than I did just a few days ago!

[Danny D]

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!

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

$33 $35 $40

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.

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.

[DD_BobK]

BIG SNIP

as long as the price for materials is well below those numbers aboveThe decision is all about quality & fitness for use, against the classic cost tradeoffs.

[ronjohnsonusa]

In my views you should refer the reviews for the customers or you can contact them and confirm.