We are likely moving away from these. To make them work you also need torque motor controllers (TMP-1 is the part number), one for each motor. This allows you to electronically control the tension and direction of rotation for each motor. The tension needs to vary somewhat as the load shifts from one motor to the other, particularly when one reel is full and the other nearly empty. But you also need to know how much to adjust the load. It’s possible to simply test this and set up some parameters in the software to do adjustments (for example, we could test the tension mechanically with a tension testing device for each film gauge, and for various amounts of film on each reel. Since we’d know programmatically how much film is on a given reel, we could ramp the tension depending on how much is there). This would need to be done for each gauge and would require a fair bit of programming logic. You also need a sensor to detect whether the film has unwound, so that you can stop the motors.
We recently switched our capstan from a NEMA23 closed loop stepper to one of these: https://www.teknic.com/model-info/CPM-MCPV-2311S-ELN/ – it’s a servo motor with an integrated controller, designed for very precise positioning applications. It’s incredibly powerful, precise and quiet. We had it running at 3000 RPM on a desk and you could barely tell it was running.
Their non-positioning motors (the SDSK series, https://www.teknic.com/products/clearpath-brushless-dc-servo-motors/clearpath-sd-stepper-replacement/ ) is what we’re probably going to use for the feed and takeup instead of the torque motors. The reasoning behind this is that you can glean some information from the controller on these motors to calculate the torque being placed on the film. It’s something we haven’t done yet, but looking at the manual and talking with their support, it’s possible. So we decided to do this rather than build in a load cell to calculate tension, something we would need to do with torque motors. They also plug directly into PLCs, which we’re using for control on our setup. It was pretty painless to get the capstan motor running. Lastly, they can be programmed so that if the tension is lost they stop within milliseconds. Look at some of their videos, it’s really impressive. this means no need for a set of sensors to detect whether the film is still threaded and tight.
The Teknic motors wind up being less expensive as well. The pair of Oriental Motors linked to above cost me about $600. the Teknic SDSK motors we’re looking at are about $300 each, but don’t require the torque motor controllers, which add another $250 total for the pair, or the tension sensors, which are about $30 each.
I would also add that the torque motors you linked to above are substantial - we chose those because of our estimated load on the scanner from scanning 70mm film. For 35mm, you’d need something that does about half the load. Also, the gearbox on this is 9:1 - that may or may not be applicable on the kinograph, so I probably wouldn’t go with this exact motor for the kinograph.