Well that's a pretty sophisticated barn door tracker. I was thinking something more along these lines, which is towards the down and dirty side of the many variations you can find on the web...http://www.astropix.com/BGDA/SAMPLE2/SAMPLE2.HTM
It's the sort that will get you up into the 5 or so minute total exposures needed for relatively clean skies. The trick to astrophotography of this type is that you are best off taking a large number of sequential exposures, then "stacking" them in PS or one of many image averaging programs available. "Stacking" averages several different exposures. It has the advantage of removing a lot of the noise that creeps into long exposure digital photos. And you can just throw away exposures with unexpected airplane trails. It also means that you can advance the crank on the barn doors only between say 15 or 30 second exposures if you want, which might be good if your setup is kind of wobbly. But technically it would be best to slowly creep the crank it you can. Don't want to make it sound too easy, the success or failure of hand advanced barn doors has a lot to do with getting the distance from the hinge to the screw just right relative to the the screw pitch so the rate of rotation of the screw has some sane relationship to a clock's second hand.
FWIW, I just looked on my local Craigslist.com and found a small telescope with a motor driven equatorial mount for very cheap. That would probably be a good way to go as well, just somehow attach the camera to the mount and away you go. And for about $380 you can buy a brand new Celestron CG-4 equatorial mount with the optional motor drive. Had one a long time ago. It was a beautifully made unit that could run unattended for hours with tracking good enough for a normal focal length lens, once you got it tweaked in on the rate control.
If I could spare gobs of time I'd be out there shooting stars beginning when the gorgeous summer Milky Way gets high in the sky at reasonable hours starting about mid July. What a sight! In a truly dark sky location is just takes your breath away.
And the Japanese saws they sell at Lowes for about $15 are all you would need, although you can spend a lot more. Really any saw will do, but the Japanese saws make really clean cuts that don't need much finishing.