You would find out that a caliper is very handy to have for checking bearing
sizes.

Many (most) ball bearings are all metric, but some applications use a
combination of metric and inch dimensions, with inch used as the I.D.

Generic (or used domestic brand) calipers are available for about $20, even
for generic digital. Most digital calipers switch between metric and inch
for instant conversions, and also can be reset to zero at any point along
the beam.

Dial calipers are generally either metric, or inch, although there are some
that indicate both on a single tool.

Shafts and housing openings are machined to sizes which are appropriate for
the desired type of fit for ball bearings, otherwise bearing sizes are
selected to fit existing parts.

WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Michael Koblic" wrote in message
...

"Grumpy" wrote in message
. au...

A 6202Z bearing is a common metric deep groove ball bearing with a metal
shield on one side. ( the Z indicates a shield on one side and a ZZ after
the number indicates shields on both sides . An R indicates a polymer
seal and RR indicates sealed both sides)
It has an I.D.of 15 millimetres,an O.D. of 32 millimetres and a thickness
of 9 millimetres. It should be readily available at any reasonably good
industrial supplier

I see. I went and found a Chinese catalogue with a search facility so I
can find the numbers and dimensions in future.
Now this may be a naive question but it puzzles me: A 5/8" shaft is 0.875
mm or 0.034" thicker than 15 mm. This seems quite a lot. Do all shafts
have to be turned down to fit the bearings? The difference seems quite a
lot to reconcile by using just heat and cold for a press fit.