Don't know what you are using, or what you're doing, but as you force
the metal to the form you have to support the backside to keep it
upright, and keep straitening the metal by bringing both the forming
tool and the back stick out to the edge, if you don't do this the metal
will fold and you will have to start over with a new piece of metal,
but don,t keep going back and forth to much or you thin the metal to
much at the foot.
also while moving the metal to the form, support the backside to keep
the metal from bulging ,make sure you have enough lubrication, and like
with all these things, practice and practice some more.
It's not that hard when you know what your doing, but it isn't easy
;--)))

Have fun and take care
Leo Van Der Loo

Prometheus wrote:
(Or anyone else who can offer some insight, of course!)

Just a quick question, if you've got time and some info for me-

I've been continuing to practice spinning, but several attempts have
ended up making a wavy edge on the outside ring of the metal (where it
has not been spun yet, and is still standing up) The mandrel shape
I've been using is a "standard" bowl shape similar to a half sphere.

Depending on the material, they either catch the tool and rip up the
piece, or lay down and fold over one another when I try to spin them
out. Once they're folded, I haven't been able to spin them out.

I'm guessing that this has to do with the way the metal stretches, but
judging from the video clips I've seen on this, it's obviously
something that doesn't have to happen.

Any clues on what I might be doing to cause this? Pressing too hard?
Not hard enough? Not enough working back towards the base? Maybe too
much or too little material?

I've got a few things to turn out, but it's still kind of dumb luck at
this point- no big "aha" moments yet... I did ask my wife to get me a
set of videos on the subject for Christmas, but that's still a month
away, and I fully intend to keep playing with it in the meantime!