So, I finally got my disc sander all assembled and located back out in my shop.
When I first brought it home, I fired it up and immediately noticed that there was far more vibration than I was comfortable with. I knew I'd be returning to that issue eventually. And that's exactly what I've been working on most recently.
Here it is looking nice, but functioning pretty miserably!
I took the disc off the hub and tried rotating the mounting locations. That might have made a very slight difference, but no real improvement. When I placed a large wrench on the sander table it would walk right off the table in a matter of seconds. Not good!!
The motor shaft measured nice and true (about .0007"), so I figured the disc must have been way out of balance.
So, I set up a jig to static balance the disc.
It was pretty clear that the disc had an obvious heavy side, as it quickly rotated, then came to a stop and reversed direction. It went back and forth (MANY TIMES) and eventually settled with the heavy spot on the bottom. So, I marked the location, then scribed a an arc and started drilling. I was thinking it would take 7 or 8 holes. NOT EVEN CLOSE. I drilled the initial holes and the disc behaved just like it did initially. It quickly rotated, did its back and forth rolling, and finally settled in the same exact spot. So, I continued to add a couple of holes, test, and repeat. 25 holes later, the disc was FINALLY balanced . I could place it on the jig in any orientation and it would sit nice and still--no more rotating back and forth.
After it was balanced, I reinstalled the disc on the disc sander for the moment of truth. I've never balanced a disc before, so I was cautiously optimistic. I fired up the disc sander and at last, it ran VERY smoothly! No more wrenches walking off the table! I even balanced a 2.5mm Hex bit on the table and it hardly vibrated. That's mission accomplished in my book. And that's pretty much a wrap for the restoration. This is definitely a keeper, which is exactly what I plan to do with it.
