I think you're limiting your search for bearings too much. MSC has 1/2"
pillow block bearings ranging from 1.126" to 5" overall length. The smaller
ones have a stamped steal pillow instead of a cast one. They also have a
bearing block with a 2-bolt flange that could be bolted to a riser plate on
each side instead of using the pillow blocks.

http://www1.mscdirect.com/CGI/NNSRAR...1&PMAV ID=219

Or if you happen to have quick and inexpensive access to the type you were
originally talking about you could weld a vertical bar with 2 holes in it to
your base plate and mount the pillows on it with the bolts going all the way
through both pillows. I'm not sure how much closer that would put them but
it should help quite a bit.

Best Regards,
Keith Marshall


"I'm not grown up enough to be so old!"


"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