On Oct 27, 10:07 pm, Ignoramus2057
wrote:
On 2007-10-28, woodworker88 wrote:

On Oct 27, 12:40 pm, Ignoramus2057
wrote:

I had a long discussion with a particularly stubborn friend of mine
about this very topic.

ABEC 7 is the grade used for machine spindle bearings, and is
obscenely expensive (when the tolerances are held to +/- 0.0001",
you'd kinda expect it to be). Nearly all ABEC 7 bearings I've ever
encountered were tapered roller bearings.

The one I have, is a ball bearing. (a pair actually).
That makes sense. Most high-precision bearings are paired, such as
for the top and bottom of a machine tool spindle.

The skateboard manufacturers just use it as a cool name, most skate
bearings are ABEC 3 at best. Most non-engineers aren't aware of the
real system.

Makes sense.

Fafnir actually makes both real bearings (I think they're a subsidiary
of Timken now) as well as skate bearings. I have some Fafnir
machinery bearings, they're good stuff. Usually the shields on the
skate bearings are colored a bright color, the ones I have are either
green or red. The equipment bearings have black shields or are
unshielded.

Right, seals are colored (they're rubber) Shields are metal, and
aren't colored. I always get them confused...

I doubt that Fafnir would mislabel even skate bearings. I think that I
will buy those fake "ABEC 7" skate bearings, and will try to measure
their balls' concentricity.

i