Sorry for the delay in updates. I have come very very close to making a final decision on take-up and supply motors. I am just waiting for one more shipment. More details below.
Right now I have a stepper motor system working with enough torque to power the entire system:
Power Supply: 48V @ 6.3A (enough for two motors)
Logic: Arduino Uno
I have not incorporated any feedback loops into the system for speed control yet. My only focus thus far was to find a motor with enough torque and to test it with a full reel on the take up side and then again with a full reel on the supply side. I'm adjusting speed manually with a potentiometer attached to the Arduino, which in turn changes the speed of the stepper.
I will post a video of the system working this week.
ON THE WAY
I found out that pancake servo motors might be exactly what we're looking for. They have a slim profile, do not require a driver (PWM signal for speed control), and are built for continuous, consistent linear motion. They are used for tape recorders and the like - so they're perfect, especially if we ever decide to incorporate our own sound reader.
I found one supplier in the UK (see PDF attached), and one in China. For the take-up/supply reels, we want something like a GPN12, and for the capstan we'd be able to get away with a GPN9.
GPN12 UK cost = $420/ea. So there's your bad news.
Right now, the stepper motor setup is around $145 each. But I want to do a comparison with both systems so we have an informed choice before we move to the next phase. Once I have the pancake servos installed, I'll send a video of both running and ask for your feedback.
GPN12 SCS.pdf (188.7 KB)