Hi Brian Lawson,

Thanks for your reply,

The reason I used two bearings instead of one, is because two bearing
engineers from two different companies recommend two bearings instead
of one. This is because using two bearings spaced apart, reduces the
edge loading, as opposed to using one long bearing. This is true
whether you use bushings or needle rollers.

This thing is just oscillated manually by hand, 1 or 2 seconds at a
time, once or twice per minute, over the course of a couple of hours
per day. The sweep angle is only about 10 degrees, i.e., 10 degrees in
one direction and then back to the start point equals on cycle. Timken
used a computer program to estimate the bearing life with the bearings
spaced further apart as shown in the housing #2 drawing at the website
link. At that time, I had a different housing and I was able to use a
little larger OD bearing that worked on a 1/2" OD shaft, but timken's
Eng. department estimated a life that was far beyond what I needed. The
life was so much more than what I needed, that I figured the 3/8" and
7/16" bearings would work OK as well, even with the different spacing
of the 7/16" bearings. The static load rating of all the bearings is
plenty in any case.

I will be using "full complement" needle rollers, packed with a high
pressure grease.

I checked into bronze bushings, but most bearing engineers say bronze
bushings don't do well for slow moving high load oscillation or
pivoting applications. I need to keep the clearance between the shaft
OD and bushing / bearing ID to a minimum. With a bushing, this
clearance will only open up with time, with a needle roller, the
clearance will basically remain the same as it is at assembly (which is
smaller than it is with most regular steel or bronze bushings) .

I was going to use plastic bushings from www.igus.com, they show good
wear, and tolerate misalignment, but they have clearances that are a
little too large. Therefore, I chose the needle rollers.

As far as what keeps the housing from walking off the shaft, please
look at the post I made right before yours, where I explain the use of
loc-tite on a screw that threads into the end of the dowel, i.e., the
dowel is a pull dowel with a tapped end.

Thanks again for your feedback,
John