"mac davis" wrote in message
...
On Mon, 23 Mar 2009 21:38:57 -0700, "Bill Noble"
wrote:

nice to have a zero or 100 low rpm..


mac



zero isn't all that useful, just turn the power off, but 5 or 10 RPM is
useful - I use that speed a lot to dry lacquer. But, with a direct drive
system,that means the motor needs to turn at that speed, and that poses
some
challenges.

There are a couple of advantages to a belt drive - one is that the motor
can
turn faster than the spindle, so you can get torque multiplication, and
another is that you get vibration isolation from the motor - not much of
an
issue with a decent motor for wood turning

Yeah, that was sort of what he said, Bill...
The low speed of 100 rpm is fine, but you always want more than you get,
right?
Also, the more I read about HOW the motor works in this thing, the more
I'm
impressed.. No windings? Weird!


mac


I just read what was posted on the Nova site about this motor - I don't see
anything amazing, it looks like, and is described like a standard stepper
motor, and not a very fancy one at that - these kinds of motors are very
common - though perhaps not on a wood lathe. The 100 RPM limit is probably
due to the design of the motor - it looks like the armature has 8 poles, so
it is probably an artifice to avoid "cogging" - the motor is actually
turning in steps of maybe 1/8 or 1/16 th of a turn - below 100 RPM those
steps may become noticable enough to bother the turner or to cause some
effect on the turned result - for example, at 60 RPM you would be having 8
steps per second - that would be quite visible.

There is a significant amount of "gee wiz" type snake oil in that motor
description - that doesn't make it bad, but does mean that you don't fall in
love with the words. If the lathe works for you, then great.

Reading the description, I think I would not like it - I would want a knob
to set speed, I would want the very slow minimum speed, and I would want a
lower tech motor so I could replace it or the controller if there were a
problem. But then, that is me and many folks are different....