|I guess the best way to explain what I'm trying to do is to explain the
|application. This is for a HO scale engine shed for model trains. The shed
|has 6 pairs of doors and I want to use a single stepper motor (one I have
|from an old floppy drive) to open and close all six.

For hobby applications, you may be best off using seperate
cheap motors for each door.  If you look at some VCR's, etc.
you'll be amazed at how far they go to economize on motors:
my old Samsung VCR (which worked very nicely until it started
having problems with the tape sensor) used one motor to spin
the drum head, and used one motor to:

  load/eject the tape cartridge
  pull out/retract the tape (wrapping it around the drum)
  propel the tape for fast forward/rewind
  move all the other wierd little doodads

The trick they use is to have the motor turn in one direction
to select a function and turn in the other direction to actually
do it.  Neat stuff.

>From your description of what you're trying to do, that degree
of unification might be excessive but making the thing work with
the stepper plus one solenoid might be quite workable.  There are
two approaches I'd suggest:

[1] Have the motor shaft run past all the doors, and have six
    "partial" gears on it, each with teeth on 1/6 of its surface
    (staggered).  Have the solenoid shift the shaft slightly (al-
    ong its axis) to cause those gears to disengage from the
    doors.  To select and open a door, then, engage the solenoid,
    rotate the shaft so the gear segment is lined up for the right
    door, then release the solenoid and turn the motor in the des-
    ired direction.

[2] Although this approach might be a bit much for 6 doors (it'd
    work better with, say, four) it'd have some advantages: rig up
    cams so that as the stepper rotates, the doors open and close
    in every possible combination.  Make the door linkages a bit
    springy, however, and have the solenoid lock all the doors in
    their current position.  To set the doors to "1, 3, 4 open;
    2, 5, 6 closed" you would engage the solenoid, rotate the motor
    to that position, and then release the solenoid.  Maybe a bit
    tricky to build, but you'd be able to operate all six doors at
    once.