"Bob Engelhardt" wrote in message
...
Michael Koblic wrote:
"Bob Engelhardt" wrote in message
I made one from a 20 lb propane tank & treadmill motor:
http://www.metalworking.com/dropbox/vibepolisher.jpg
... I was not clear about the concept: The motor spins an arm which moves
the bowl in a circular eccentric fashion? I somehow expected the movement
to be up and down.
Correct. Since the bowl is not actually rotating, the effect is a
back-and-forth motion. This back-and-forth against the curved sides
causes the "media" to have a rolling action: it actually flows up the
sides & middle and down in between. It was quite surprising the 1st time
that I saw it.
Presumably the adjustment would be achieved by regulating the length of
the arm and thus the amplitude of the vibration. The frequency of the
vibration is then given by the motor rpm (I guess yours is adjustable
being a treadmill motor). I see the recommended frequency is no less than
1600 Hz so an ordinary induction motor would do.
Correct again. I read somewhere (Eastwood , I think), that their
vibrators ran at 3000 rpm, so that I what I used. The frequency makes a
huge difference. Not knowing what-the-hell was going to happen the first
time I ran mine, I started out very slowly & worked up. At some point -
the resonant frequency, I suppose - the action was VERY violent!
Increasing it further, it quieted down & at 3000, it was very smooth (but
NOISY).
I have done a ton of research on this but eventually one has to get one's
feet wet. I was reluctant to spend money only to find out that the whole
thing is completely useless for my purposes. I am actively looking for
someone who has one to tumble a couple of my parts and see if it does the
job.
Heh - I have used mine pretty much not-at-all. Another one of those
projects whose point was to build it, not have it G. It does polish
silverware nicely - corn cob media , with a touch of rouge.
Only some companies give you full details of their units. Some would not
tell me their frequency even when I asked directly. GoodVibes run at 3000. I
am told the higher the better.
Then there is the other approach:
http://www.youtube.com/watch?v=PvGYf...eature=related
http://www.youtube.com/watch?v=xq1hX...eature=related
http://www.youtube.com/watch?v=ESl-_...eature=related
Of course rotary tumbling would be simpler...
--
Michael Koblic,
Campbell River, BC