On Fri, 8 Mar 2013, Chuck Guzis wrote:
  It was my original statement that referred to
"spiral"  when I meant helix.
 On the other hand if you take the definition:
 "A three-dimensional curve that turns around an axis at a varying
 distance while moving parallel to the axis." with the variation of the
 distance being infinitely small, you have a helix.  In other words, a
 helix is simply a degenerate case of a three-dimensional spiral.
 But I did mean "helix". 
Nothing wrong with that.  But that's why we needed clarification
and disambiguation for visualization.  That was why I asked whether
it was like the stepper of an SA400 or like a Micropolis 5.25.
Making one scale out of a transparent material opens up lots of
possibilities.
Or, the scale could be mechanically linked to a potentiometer,
followed by either A/D or analog computation.
Whoever comes up with the stupidest idea should patent it,
since that's here the money will probably be.
--
Grumpy Ol' Fred                     cisin at 
xenosoft.com