Stand the pillow blocks on end and you can get em pretty darn close
together. Wedge em apart for spacing.
And no the brass bushings won't take the 24+ hour runs a tumbler would need
for long.
"Christopher Tidy" wrote in message
...
Hi all,

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.

Best wishes,

Chris