The one problem I found with Walgreen's toothbrushes is that they
just wiggle around too much. They actually make better for automobile
body work than for tooth enamel, imho.
GREAT hint about the sewing machine. Since circa 1950 machines can be
found in working condition at yard sales I can certainly try this
I found a Water-pik toothbrush with a ni-cad battery which was
discarded due to problems recharging. Has a nice gentle hum, I wonder
if it could also double for gem setting if a metal tip is put on it.
I think I could hook up a DC supply to it.