"Alex" wrote in message
om...
My question is about life expectancy on following linear slide setup:

Two parallel 5/16 rods and a slide that uses a pair of small plain
ball bearings(5mmx12mmx5mm) on the same
axel with the spacer between them instead of a each single grooved
roller.
The
ball bearings will roll on the both side of the rod since the spacer will
be
shorter than rod diameter.

It's a preloaded design with preload no more than 10-15lb.
Speed is 1 foot/sec.
It's manually driven device and "high mileage" is not expected.

I understand that radial BB are not made this kind of thrust load but
since
it's a relatively light load I think that it should work fine.

What do you think? Is it acceptable compromise?

Alex,
Consider that the bearing you are using has a speed rating of probably
50,000 RPM, and a load rating of about 100 lbs, and assuming it doesn't rust
away. The answer is that you'll never wear it out.

Gary H. Lucas