Next visit, I hauled everything back to Central Ohio, and the restoration began last fall. Everything was in pretty fair shape except for overspray on the finishes. That cleaned up well with denatured alcohol, plus some laquer thinner for a few stubborn spots. That Shopsmith finish is darned tough .. only one casting needed touch-up paint after my chemical assault.
The bandsaw had a frozen backup bearing, so I went ahead and replaced all four ... the complete set was on special for about $20. The Power Station front spindle bearing had one slight rough spot, so I replaced that as while I was at it. The old bearing came off easily with a gear puller (I wasn't worried about trashing the bearing), and the new one (about $7 online) pressed on nicely using a tube against the inner race and an arbor press.
When I fired everything up, though, I was disappointed at the amount of vibration. I had read Bill Mayo's recommendations on link belts, and decided to give those a try. I'd guess that the new link belts eliminated over half of the vibration, but I still felt it was excessive. The Power Station was clearly the culprit, as it would vibrate even with no SPT mounted. The amount of vibration was very speed-dependent, being much worse at certain resonant frequencies.
While I was cleaning up the Power Station, I had noticed that the spindle housing and the motor were mounted to one another only through the sheet-metal top of the stand -- and the sheet metal was flat throughout that section. Well, flat sheet metal is just not very stiff -- and it was making like a leaf spring between the the spindle housing and the motor. Whenever the belt speed hit a resonant frequency, the vibration got bad.
So I got ambitious and made a pair of stiffening brackets out of angle iron (2" wide with a 1/8" wall, if memory serves), and painted them with Shopsmith touch-up paint. The stiffeners span the sheet metal between the spindle housing and the motor, and are captured by their respective mounting bolts. (I did had to buy longer bolts for the spindle housing).
The stiffeners provide a much more rigid connection between the two major masses, and so greatly increase the resonant frequency -- apparently to something above the drive-belt excitation frequency, as they work like a charm. Power Station NVH (Noise, Vibration, and Harshness) is now on a par with my Model 520.
EDIT: One year later ... here's a link to a video of the stiffened power station in operation.
- Power_Station_stiffeners.jpg (160.78 KiB) Viewed 2843 times