127mm Zeiss Ikon rangefinder cam for Polaroid pack cameras

This thing replaces the rangefinder cam in a Zeiss Ikon rangefinder made for Polaroid pack cameras which come with the 114mm lens so that the rangefinder will work with a 127mm lens. When replacing the lens with a 127mm lens (from a model 110A for instance), the rangefinder does not indicate accurate focus through the range of focus. This cam corrects that. This will not work with the 2 window folding or fixed rangefinder, which has a different cam that's riveted in place.

It was modified from the cams that came with the Panomicron Rhodium. That cam had too much play on the mounting bolt, causing inaccuracies with the rangefinder, and the cam surface was modified slightly for more accurate focusing. The surface which controls the framing was also modified to help with framing at closer distances, as the original was flat.

Print with minimum height (.12mm works OK). I used PETG so if the camera gets hot, it won't melt. Remove the rangefinder cover and unscrew the 3 screws on the bottom. You don't have to remove the rangefinder from the camera to do this. Release the spring against the screw hole and carefully remove the circlip (it's easy to lose if it goes flying), then remove the cam. Install the spring in the cam and install it with the circlip and stretching the spring to the screw hole. I purposely made it so it's a tight fit on the shaft. You may need to file/drill it out slightly to make it fit, but it should fit firmly. Even a very small amount of sloppy movement from a loose fitting shaft will cause the rangefinder to be inaccurate (.05mm is significant).