Hi all,

When I was about 8 or 9 years old I really, really wanted a stone
polisher. I think they were rather expensive and also (probably wisely)
my parents thought that I would be bored having to wait months for
results, so I didn't get one for my birthday. Anyway, I woke up in the
night and it occurred to me that a stone polisher (or rock tumbler as
some people call them) would make a great home shop project.

I figure I can make a drum (probably cube-shaped) from welded 1/4"
plate. The drive is going to be more of a challenge (I don't have a
great deal of cash to spend on this). I reckon I probably need about a
30 rpm drum speed and 50 W of power for a small polisher. But the drive
needs to be sturdy and energy efficient if I'm going to leave it running
in the shed all year. A mulit-stage belt drive will be fiddly and
probably not very energy efficient. It seems to me that the best
solution would be an oil-filled worm and wheel gearbox, but I'm not sure
where to scrounge one from. Can anyone think of pieces of industrial
equipment which use a suitable gearbox, which I could look out for in
piles of junk etc? Has anyone built one of these before? Any ideas would
be welcome.

Best wishes,

Chris