Have been practicing with the bowl saver on some nice sweetgum. First,
there are a lot less shavings, since there is only the outside shaping
of the blank and the hollowing out of the smallest bowl. Second, it is
faster--even if you don't need the smaller bowls. Just throw the inside
bowl away and you are done. In three days it has probably paid for
itself providing I can sell the smaller bowls, and sweetgum bowls sell well.
500-600 rpm. I haven't gotten confident enough to go any faster. It
still surprises me if I go too far and the inner bowl just drops down
and bumbles around inside the larger bowl. I fully expect it to go into
near earth orbit. Pleasant surprise.