[APML]: barndoor tracker question

[Jim Fedina <jfedina@sbsusa.com>]

To all who have used a barndoor tracker,

I am currently reading a printout from a webpage that describes building
a low-tech barndoor drive. Brian Rachford wrote the article (just in
case anyone has read it). When polar alignment comes into the picture, I
get a little confused. I know it's simple but it eludes me. You must
polar align these drives before using them. After polar alignment, how
does the drive get turned into another direction? In other words, I
polar align the drive with the north celestial pole. Then I want to take
a 10 minute exposure of Orion. the NCP is to the north while Orion is to
the south. How do you mantain polar alignment while turning the barndoor
drive? Is it that the barndoor drive stays pointing at the NCP and you
turn the camera only? I'm trying to think of how that theory would work
as I am writing this.
Any knowledge someone can share with me on this matter would be
appreciated.

Thanks,
Jim Fedina