Film-Tech Forum ARCHIVE: Changing Sprockets On a JJ

This is topic Changing Sprockets On a JJ in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Don Furr (Member # 1469) on 02-25-2013, 05:42 PM:

The 35mm top and bottom sprockets on my JJ are worn and need to be replaced. Since I don't run 70mm film on this projector I would like to replace the combo-sprockets with straight 35mm VKF sprockets. (the intermittent is already a straight 35mm)
Has anyone had experience in doing this conversion. I realize that some type of bushing must be required to keep the sprocket shafts from pushing in.
Any suggestions would be appreciated.

Posted by Louis Bornwasser (Member # 3063) on 02-25-2013, 07:30 PM:

Yes. They actually made a part to do that: 17.5mm spacer. I suppose flat washers will do if the hole is a slip fit and the stack is 17.5mm. Good form to keep the OD of the washers smaller than the new sprocket so the pad roller doesn't bump them. Remember there is a little bit of slop on the gear screw and the sprocket screw to allow fine tuning. Louis