Having been busy with other things, I haven't started to build my stone polisher yet, but I've had chance to ponder the design a little. Often I like to do this because I find after a week or two a smart idea will come into my head, which I would otherwise have missed.
Anyway, I have a small problem with bearings. I intended to use self-aligning ball races in pillow blocks, but it turns out that the pillow block for a 1/2" diameter shaft is 5" long! So I can't get the shafts closer than 5" apart unless I stagger the pillow blocks, which will look messy. I want about 4" between the shafts, and I might make this distance adjustable to allow different barrel sizes to be used on the same machine.
Pillow blocks don't seem to be available for shafts less than 1/2" diameter. I don't have access to a milling machine, so I can't make my own "double pillow block" to carry two ball races. One idea I've had is to use rod end bearings (as used in pneumatic cylinder linkages etc). These could be attached to a base plate with a single bolt, provide the self-aligning feature, and to cater for the rotation I could press a bronze bush into the eye. I've checked and I can get components of the right dimensions to make this work, but my local bearing supplier didn't want to recommend it because the idea was unconventional.
What do people think? Will rod end bearings with a bronze insert stand up to continuous use in a rock tumbler if I keep them clean and well lubricated? Any thoughts would be much appreciated.