Hi, I’d like to share my experience, which began with this post:
I made progress on the design and finished a scanner model that allowed me to digitize about 25 35mm film canisters. I was going to write a post with the details later, but I didn’t get around to it… so I’m taking advantage of this thread to give a quick overview of what I did and the solution I found for counting the perforations.
I tried lasers and various types of sensors to detect perforations, as well as OpenCV, but nothing really convinced me. At one point during development, I doubled the roller’s teeth and used a “limit switch” to count the steps/perforations. It worked well for a while, but mechanical wear took its toll, and failures became constant. So I reconnected a speed sensor between the duplicated teeth… and it turned out to work very well!
I’m not sure if I made myself clear, so here’s a playlist of all the steps I took; video 11 shows the latest version. The roller with the sensor is the one on the right (as you look out the window) with the duplicated red teeth. If this helps anyone, I can provide a close-up of it or give more details.
With this sensor, I can also measure the time between perforations and, using that data, automatically adjust the motor speed so it self-regulates as the roll advances.
I’d like to thank everyone participating in this forum once again.
My next step is to try to build a more stable prototype and share the results.
I’m also sharing the website for the archive restoration project that inspired the construction of this scanner, where you can also view the scanned material.
Playlist
https://www.youtube.com/playlist?list=PLttC-5UygTjY19Bxm9bDm3GcEeGjVzq1z
Web:
www.mascarocine.org/elfutboldeayer
Sensor:
Saludos desde Argentina
Carmelo.