On Sat, 08 Jun 2013 20:59:08 -0700, DD_BobK wrote:

My comment "I just buy the cheapest ones... cuz price the only thing
that matters." .... was facetious.

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-bear...dial-play.html

The problem, of course, is obtaining this information.
Luckily some supply houses specify both the tolerance & radial play:
http://www5.picturepush.com/photo/a/...g/13272553.png

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/be...ngs/index.html
http://www.abbottball.com/materials/...-balls-302.php