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).
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).
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!
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:
$33 (Amazon.com product link shortened)
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.
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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