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About a year or more back I bought a 645 film back form Cherryrig which didn't work properly, I can't remember if the film counter didn't work or if it didn't wind the film on.
Anyway, I started taking it apart but couldn't get one screw out so I put it back on the shelf. Yesterday I decided to drill the screw out and steal one from my 220 film back that I don't use. Turns out the reason I couldn't get the screw out was because it has a left hand thread instead of a right hand thread. Luckily I found this before I drilled the screw out.
So the problem is there are two circular plates under the film counter which sit on top of each other, one is fixed to the film counter and the other is meant to be free to rotate a little. Each has a set of groves cut into it's edge which overlap and there is a separate lever which sits in the grove preventing the film counter from rotating. When the shutter fires the lever retracts from the groves and the free plate is meant to rotate so that the groves don't over lap, it does this under the tension of a very tiny spring. As the film is wound on the film counter and the fixed plate rotate around until it catches up with the free plate and the groves line up. At this point the lever engages with the grooves and locks the film off ready for the next shot. The problem is that the free plate is sticking and so sometimes when the shutter fire the grooves stay lined up and the lever goes into the same position. This means the film doesn't advance and so you end up shooting over the same bit of film.
I've separated the plates and there was a bit of oxidisation on one of them which could have been causing the friction. Alternatively the spring might have lost some of its tension over time.
Do you think these plates should be lubricated or should they be dry? If they should be oiled what sort of oil would you recommend?
Alternatively, is there anywhere I can get Bronica spares from?
These things really are a work of art you know, proper engineering excellence (relatively speaking, it's a camera not a space shuttle
)
Anyway, I started taking it apart but couldn't get one screw out so I put it back on the shelf. Yesterday I decided to drill the screw out and steal one from my 220 film back that I don't use. Turns out the reason I couldn't get the screw out was because it has a left hand thread instead of a right hand thread. Luckily I found this before I drilled the screw out.
So the problem is there are two circular plates under the film counter which sit on top of each other, one is fixed to the film counter and the other is meant to be free to rotate a little. Each has a set of groves cut into it's edge which overlap and there is a separate lever which sits in the grove preventing the film counter from rotating. When the shutter fires the lever retracts from the groves and the free plate is meant to rotate so that the groves don't over lap, it does this under the tension of a very tiny spring. As the film is wound on the film counter and the fixed plate rotate around until it catches up with the free plate and the groves line up. At this point the lever engages with the grooves and locks the film off ready for the next shot. The problem is that the free plate is sticking and so sometimes when the shutter fire the grooves stay lined up and the lever goes into the same position. This means the film doesn't advance and so you end up shooting over the same bit of film.
I've separated the plates and there was a bit of oxidisation on one of them which could have been causing the friction. Alternatively the spring might have lost some of its tension over time.
Do you think these plates should be lubricated or should they be dry? If they should be oiled what sort of oil would you recommend?
Alternatively, is there anywhere I can get Bronica spares from?
These things really are a work of art you know, proper engineering excellence (relatively speaking, it's a camera not a space shuttle
)