"Bob La Londe" wrote in message
...

"Ignoramus821" wrote in message
...

All regular ball bearings are very cheap nowadays and even cheap
ones
are well enough made for miscellaneous use. Enormous progress in
making them cheaply and industrially. No need to hoard bearings,
just
buy them as you need them cheaply.

i


In Yuma, Az there is one major bearing reseller that I am aware of
and the few times I have priced anything from them they seemed to
think this was still the 1970s where I had the choice of buying from
them or doing without. Other than that there are the usual hardware
store bin bearings which are typically only small sheet metal ball
bearings suitable for movement with light loads. There are a couple
other sources, but they all say, "we can get it for you." Now I am
not talking about a particular spec bearing to repair an old
machine. For those I always get a high quality spec bearing to
match the old one, and often I have to check multiple sources to
find somebody who has it or has a good quality crossover. They are
almost never cheap.

In this case its more along the lines of deciding I want to build
something. Usually in the evening or on the weekend when I have shut
down production in the shop. Sure I can't have everything, but I
can have a lot. Skate bearings are pretty amazing. 4 of them can
handle a thousand pounds rolling load for a while, and a few hundred
indefinitely with a quality grease. When you think about it that's
insanely good for such a tiny little bearing. Put some preload on
them and you can even make a light duty spindle out of them (I have)
that's perfect for cross drilling or cross tapping on the lathe. I
don't know how long they will last as my first one shows no signs of
wear yet. I was just looking for a couple larger bearings I could
spend a couple hundred bucks on and have a bunch of them in the
project bearings drawer on my back assembly bench for those weekend
inspiration projects.

For me usually the shaft diameter determines the inch or metric
bearing. Hardware store and second-hand pulleys are typically inch and
may be difficult to rebore accurately, so they need inch shafts and
bearings. When I make everything from scratch I can use metric sizes.
Ultimately the motor torque or the axle load defines the minimum shaft
diameter, see my thread on Lovejoy couplers.

The temporary setups I've seen in engineering labs were often built
from 80/20 extrusions and pillow blocks. The local bearing supply
house told me 3/4" and 1" are the most common shaft sizes they sell
for prototyping.