With a roll of 35mm film, the ridges touched the film just about where the perforations are- causing no problems at all. Our need to improvise for other film types is what causes the contact issue. It was a cheap, "hobbiest" piece of gear, like the "daylight developer" system, a bakelite tank that allowed you to place the unopened film cassette in a small opening, feed the film through to a tank and then do all of your chemistry without exposing the film to light. It works fine on old Kodak cassettes loaded with thick Kodak film, like PanX or Verichrome. Try it on a roll of Ilford, or Foma, Efke or even modern Kodak and you will be swearing in seconds.
Originally Posted by David Lyga