I'm still stuck on the platen movement. Or rather I got stuck, tried several times to get unstuck and, failing that, have put the project on hold. This is completely due to my lack of electronics skills (and lack of time to aquire some), not because the project itself is extremely hard or complex. On the contrary, my hunch is that someone with skills in electronics would solve this easily.
Up to date overview: I have a PC-controlled Arduino board that controls small servo arms that turn pages in a book (see last video above for the latest setup). That already works fine. I've had it turn 50+ pages in a row without error. I now only need to control a stronger motor to move the platen up/down. Arduino can't power such a stronger motor by itself. External power is needed.
So I need: (1) a stronger motor (stepper motor), (2) a special circuit (h-bridge) acting as a middle man, (3) an external power supply, (4) arduino code to control that motor. I have two stepper motors. One lacks a data sheet so I've set that aside. The other is a 5 wire unipolar motor with detailed data sheets available. I have two salvaged external power supplies (18V and 30V). I have schematics for building a new h-bridge for the 5 wire motor. I have found code tutorials for controlling it all through arduino. But: I don't know what power supply will suit (as in not destroy) my other parts. I would need very specific advice on this point, i.e. I'd need someone who knows these things to take the data sheet info, do the math and give me a certain verdict. Like answering yes or no to this: "would the the external power supply labelled 18V, 1.1A be suitable for my 5 wire stepper motor (given the the unipolar h-bridge circuit, given the wires used, given the arduino board)?"
Here is the arduino forum thread with data sheets and other details: http://www.arduino.cc/cgi-bin/yabb2/YaB ... 9937/30#34