I like to start between centers, making use of a pin chuck or pin jaws.
Others claim they need the "artistic freedom" to reselect their axis after
preliminary turning, and so use their spur center. A Google search shows a
number of these to be the same who tell horror stories about blanks
departing the lathe at speed. I have cut and split a few hundred cords of
wood, so I can tell with reasonable certainty what is available in the log.
When I make the preliminary cuts I reveal more, and can examine still more
as I begin to rough on the bandsaw. Aside from modifying the original
concept of the piece to avoid a bark pocket that went too deep, that
suffices, and I've _never_ lost a piece held with pin and tailstock. Also,
I have never made _the_ piece, and probably never will. Each is yet
another, and if it's not perfect in my mind, the next will be better.
You can get pin jaws for your Nova, and they give you a few other creative
options as well.
I don't know about variable speed, having only four on Ol' Blue, but if it
bounces, I also believe slowing can help. Other options include removing
some wood with a gouge, scrub plane or forstner bit to equalize the weight.
It does, of course limit you, as wood so removed cannot be returned. If you
have a real pin chuck
http://personalpages.tds.net/~upgeorge/index.html you
can mount a plywood disk with holes to bolt counterweights into ahead of
your piece. Be sure to use fiberlock nuts or add some CA to keep them from
unwinding. I suppose the Cole jaws and long bolts available for your Nova
would work as well.
Last advice is to say don't cut the edge of the bowl, cut the bottom up. If
you have the nose of the gouge alternating between wood and air, you're much
safer if the gouge is supported firmly and close to the piece on the
toolrest, versus some mixed strong arm/hip rest method.
"RP Edington" wrote in message
om...
Hello,
I have a large walnut bowl blank (actually two). They are around 18"
in diameter and I suspect weigh about 45-50 lbs apiece. I have a PM
3520 and an 8" Oneway faceplate, and a SuperNova with the power jaws
(3"). I am a little nervous about turning something this large, but I
want to! I usually put the face plate on the top of the bowl and cut
the outside and the fixing for the chuck and then turn it around and
cut out the inner portion of the bowl. I will use the tail stock as
much as possible.
Any other considerations I am not thinking about? I have a new Sorby
bowl gouge and a wolverine jig. I want this to be pretty, so any help
you can offer I'd appreciate.
When I get these I also have two large Aromatic Cedar (17") and four
17" Maple blanks waiting. All these are green.