Contax I ribbons

Sarcophilus Harrisii said:
That's an interesting point. I tend to agree with you. The first Contax II I changed the ribbons of was a 1936 model. The ribbons were very weak. They looked quite OK, but when you applied some tension to them, they disintegrated. The fibres no longer had any structural integrity. They were too old. The last one I did was a one owner Contax II I bought it. I have the ribbons, intact, from this one. I picked the stitching apart and extracted them from the curtains and the rollers. These are not falling apart. They feel quite strong and look in sound condition. Same colour, same weave, same blue thread used in the stitching that I have seen in other Contaxes with genuine ribbons. This example is also a 1936. How odd. If you didn't know better you might have been tempted not to replace them. I did, of course, with Aki Asahi material, for peace of mind. Two Contaxes, same year of manufacture, same material, ribbons in completely different condition. No conclusions I can come to about why they have aged so differently. I have no idea. Just reporting what I've observed.
Cheers,
Brett
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Interesting observation Brett. But maybe they are not original? Or just who know how each camera was used and storage all this years..
 
Deklari said:
Dralowid said:
2)From my bad experience, this problems comes from ribbons installation. When I loosing tension on the bottom roller. Do anyone know average of ribbons lifetime on this camera?
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Ah!!!

Are you saying that a sudden release of tension when your screwdriver slips while trying to reduce the tension causes the spring to deform?

Or are you saying that even if the tension is released very smoothly the spring still deforms?

Either sounds likely but the thought of maintaining some tension to keep the spring in shape while replacing the ribbons does not sound like too much fun...
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Deklari said:
Also heating will defiantly result the quality..
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If you can successfully re-shape the spring by softening it with heat, I would be inclined to try to find a small spring-making business who would be prepared to include it with a batch of their own springs to re-harden and temper it. Temperature and time are fairly critical for tempering springs. The material would also be a factor, but there is no way to be sure of that.

The end where it fixes to the axle would have to be made softer so it can be bent more easily through the hole.
 
I know I've read a few times that one guaranteed way to break the centre spring is to rotate the curtain the wrong way around the shaft, against the spring coils. I can't speak to the veracity of this point, because I've studiously avoided doing same.
 
It wouldn't probably be too difficult to install the three springs carefully taken off a good donor Kiev drum in a Contax I drum. All you have to do is to anchor the three springs as per Rick Oleson's clear sketches. You don't need to manually tension the springs while doing this. You just need to secure the springs where they ought to be anchored, and reassemble.
 
Dralowid said:
Deklari said:
Ah!!!

Are you saying that a sudden release of tension when your screwdriver slips while trying to reduce the tension causes the spring to deform?

Or are you saying that even if the tension is released very smoothly the spring still deforms?

Either sounds likely but the thought of maintaining some tension to keep the spring in shape while replacing the ribbons does not sound like too much fun...
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No it only only happen if fall down when the screw is loosened.
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Grytpype said:
If you can successfully re-shape the spring by softening it with heat, I would be inclined to try to find a small spring-making business who would be prepared to include it with a batch of their own springs to re-harden and temper it. Temperature and time are fairly critical for tempering springs. The material would also be a factor, but there is no way to be sure of that.

The end where it fixes to the axle would have to be made softer so it can be bent more easily through the hole.
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I worry if spring will more fragile after heating
 
Highway 61 said:
It wouldn't probably be too difficult to install the three springs carefully taken off a good donor Kiev drum in a Contax I drum. All you have to do is to anchor the three springs as per Rick Oleson's clear sketches. You don't need to manually tension the springs while doing this. You just need to secure the springs where they ought to be anchored, and reassemble.
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I have installed old (heated) spring, it take 3 hours! But not luck. After heating the spring become too soft. After increasing tension central spring loose top anchoring and make a mess again. Conclusion: 1) Don't lose your time to try repair old spring..:) 2). It is possible to install a new spring (from Kiev or Contax). You will need: good tools, magnify glasses, time and patience, many many patience! I will wait for new "donor" now.
 
Highway 61 said:
It wouldn't probably be too difficult to install the three springs carefully taken off a good donor Kiev drum in a Contax I drum. All you have to do is to anchor the three springs as per Rick Oleson's clear sketches. You don't need to manually tension the springs while doing this. You just need to secure the springs where they ought to be anchored, and reassemble.
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Rick's drawings simplify the springs. On the Contax I the outer springs have a small inner coil adjacent to the anchorage point and the spring goes through the hole twice between some of the turns. The same (ish) applies to the central spring making them all difficult to remove and replace without mangling. I don't know if the Kiev/Contax springs go through the anchorage point just once as per his drawings.
 
Pioneer said:
It all just seems a bit odd. I have breakdown drawings and assembly instructions for all kinds of different types of shutters, but only parts and pieces of this one. Are there patent drawings and descriptions, or were those destroyed in the War?
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I have talked to Zeiss. Carl Zeiss does not have any service manuals for Zeiss Ikon cameras. They actually never produced this camera (probably I should know this). Zeiss Ikon discontinued the production of camera equipment in the early 1970s. The company has ceased to exist. They forward me to Zeiss Ikon AG Stuttgar.
 
Dralowid said:
I don't know if the Kiev/Contax springs go through the anchorage point just once as per his drawings.
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Yes they do. So according to what you explain, there are differences between the Contax I and Contax II/III assemblies in that infamous drum roller, and not only for the main axle length.
 
For Highway 61.

IMG_2847 by dralowid, on Flickr

This is the spring for the right hand side roller (seen from the back). Apols for the pic, I haven't made the effort to dig up the macro stuff.

You can see the wire coming from the larger spring and then going round the shaft a few times and going through the hole twice. Talk about belt and braces! I'm sure it doesn't need to be this crazy but this is how it is...or was.

The central spring is worse because the inner spiral runs the length of the spring as per Deklari's diagram.

One would think it would be OK if it just went through once and was bent over simply????

Michael
 
Highway 61 said:
Yes they do. So according to what you explain, there are differences between the Contax I and Contax II/III assemblies in that infamous drum roller, and not only for the main axle length.
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I cant see different in drum roller. Only in main axle length and left vs right
IMG_3449.jpg
 
Isn't it possible on a Contax II/III assembly to move the right spring to the left and the left spring to the right and to leave the central spring where it is and to install the whole assembly into a Contax I? The central axle seems to fit into a Contax I without much alteration when it is turned left to right, but maybe the central spring has to be turned then too.

On the picture of Deklari it seems as if the central axle on a Contax I is the same as on a Contax II/III but simply turned around.

Erik.
 
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