Zorki 3M full CLA, part 2

A short series on fully servicing a Zorki 3M.
In this episode I'm covering shutter curtain bounce and the possible fixes.
#apxvintagecameras #camerarepair #shutterrepair #camerarestoration

[@atf2940]

Very well explained! As to the break: Since you will change the ribbons anyway, can't you shift the drum counterclockwise by one tooth so that the brake nose touches the spring properly?

[@AlinCiortea]

Well, that's what I was trying to point out... Since the motion limit is given by the lower roller that's screwed to the shaft, the end position of the shaft can't be shifted. I'll try to show this in the next video.

[@atf2940]

@@AlinCiortea Perhaps I mixed things up, since I had just replaced the ribbons on a model 1 before I watched the video. With that model you can change the resting position of the drum shaft by adjusting the relativ position in the restricting gear -- but, of course, there is no brake to be affected by this. Now I recall that the 3M with its square cut out is slightly different. -- I may have good (?) news for you, though. I just opened the 3M I have kept and found the very same situation: in the resting position, there is paper-thin gap between the nose and the braking blade. Fault or design? Perhaps the blade only takes up a minute overshoot at the moment the curtain actually closes. (A slow motion recording may show this.) In any case, I can see no sign of shutter bounce on my negatives. [Correction: Fault, but it may not matter much -- see Alin's next video.]

[@atf2940]

And I also just opened my 3C from 1956: same thing. (To be more precise, although -- other than with the 3M -- the nose slips well under the blade, it doesn't touch it in the resting position.) So, most likely this is by design. There may be a reason: If the nose touched the blade when the second curtain is about to close the window, how would you guarantee that the curtain really does complete its travel? There is a thin line between preventing bounce and allowing the curtain to close completely. Some very minute adjustment would be required. (In the Leica III the adjustment is made with an eccentric screw.) Practical solution for the Zorkis: keep the tension on the closing curtain as low as feasible. (IMHO that's good practice anyway.)

[@AlinCiortea]

@@atf2940 I'll try to touch up these things in my next video because they're things that bugged me many times, even if they probably have little relevance in real world use of the camera.