(i hope i'm not hi-jacking the thread)
i'm experimenting with a homebrew ultrasonic gizmo right now. it's basically just a small electric motor with an offset and weighted pulley (to make it vibrate) and i've got it fastened to the side of a round tupperware container. i'm powering it with a variable output power supply, so at different settings i can get some pretty good "wave action", lol. i've got a handful of pennies on the go, and have been shaking them for a total of about 2 hours and i've already changed the water several times. it gets murky, so i guess that's from the dirt coming off the coins.
i initially tried using aquarium gravel and even though it moves around a bit within the container, it's too large and doesn't seem to do a whole of cleaning, only in spots where it's touching the coins.
then i tried mixing some beach sand in with it and the aquarium gravel kept coming to the top of the sand. (who says rocks won't "float", haha!) i've got most of the gravel out and now i'm just using mainly the sand.
it's not getting the coins
shiny, but it IS taking the dirt off.
lol, for the amount of time i've had them shaking, i could have easily had them scrubbed several times over, but this is less work, haha!
then again, the time frame is really not much different than it would be if i were using a tumbler.........
again, sorry if this was a hi-jack to the thread.