Contax I ribbons

Highway 61 said:
Congrats. Again - that was the way to go. Now finding a good Kiev bottom roller will be easy and cheap.

And now you can set yourself as a worldwide famous Contax I repairer ! ;)
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Thanks :D I have already order working Kiev from Russia ..I hope to received it by end of this month and finish shutter..
 
Fantastic, Deklari. Today I was not at home, I am really surprised by your achievements now I see them. You are very inventive. Great job. I hope the installation of the Kiev roller will be successful and that you'll have the patience to wait until the Kiev arrives.

Erik.
 
Erik van Straten said:
Fantastic, Deklari. Today I was not at home, I am really surprised by your achievements now I see them. You are very inventive. Great job. I hope the installation of the Kiev roller will be successful and that you'll have the patience to wait until the Kiev arrives.

Erik.
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Thank you Erik, Now only question if new roller and ribbons will work properly.. :)
 
Deklari, Great stuff and very helpful! You are leading the way.

Yesterday I ordered a Kiev roller and some new drill bits to do a tidy job.

One thing that I'm thinking about. I will need to re-do the ribbons and think it might be worth trying to glue them rather than sew. (like the camera with the blue ribbons).

I would probably use a cyanoacrylate gel (thick super glue).

Any opinions?
 
Dralowid said:
One thing that I'm thinking about. I will need to re-do the ribbons and think it might be worth trying to glue them rather than sew. (like the camera with the blue ribbons).

I would probably use a cyanoacrylate gel (thick super glue).

Any opinions?
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I used to know a repairer (now retired of the camera repair business) who went the glue route for Contax and Kiev ribbons replacement. According to him it worked very well and proved to be durable even with Aki Asahi silk ribbons.

But the glue of choice is the regular cyanoacrylate glue, liquid. The gel is too thick.

The glue has to be typically applied with a small pin, and the glued area has to be gently pressed with a pair of plyers so that the cyanoacrylate gets into the ribbons fabric fibers, so that the two sides of the ribbons get soldered, sort of.

In my opinion, when you repair your own camera, the sewing technique remains the good way to go even if you spend one hour per sewing point. The gluing technique makes sense for someone billing out his working time and having many other cameras to repair for his customers.
 
Another piece of high class Zeiss engineering, excellent helical revealed.

IMG_2860 by dralowid, on Flickr

A by product of Contax I repair will be a simple Contax to Nex adapter using the left over bits from the remains of a Contax II!
 
Dralowid said:
I would probably use a cyanoacrylate gel (thick super glue).

Any opinions?
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I'd prefer two components glue (Bison Kombi Power). It dries slowly, so you'll have maximum control. Enormously strong, much stronger than super glue. You must have patience for the drying, though.

Erik.
 
Yes Bison Kombi Power looks like a a straightforward epoxy, I use plenty of that for sticking my boats together. It is excellent.

Michael
 
Dralowid said:
Deklari, Great stuff and very helpful! You are leading the way.

Yesterday I ordered a Kiev roller and some new drill bits to do a tidy job.

One thing that I'm thinking about. I will need to re-do the ribbons and think it might be worth trying to glue them rather than sew. (like the camera with the blue ribbons).

I would probably use a cyanoacrylate gel (thick super glue).

Any opinions?
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Michael,
I've always stitched the ribbons on, even though I went to the trouble of getting some of the Super X adhesive Aki recommends on his website. I'll probably use it to glue ribbons onto fabric curtains for other sorts of cameras, instead. I wasn't too sure what the best choice of thread type was for the application. Eventually, I decided that absolute certainty in all things with 80-odd year old devices may be unrealistic, and that, if silk was strong and durable enough for the ribbons, it was a fair bet for the thread, too. I've been using pure silk thread bought from a local fabric store. Aki's ribbon is black, so white thread has been helpful as it stands out against the material when you're threading it through.

The ply of the thread I have used is quite thin, thinner than what was used originally, comparing it to the threads I've removed from original ribbons. It's something like what one might find on one's shirt buttons, perhaps? I can check the spool if needed. But because it's thinner and smaller I have been using two threads per end, side by side, to fasten ribbons. Partly because they will fit without fouling anything, having smaller knots that don't protrude as much. Also, because the thread is thinner, for safety and peace of mind.

So far, so good. When I tested my friend's Contax II before sending it back to him I was working on a decent blister on my right thumb, having exhaustively tested every single speed dozens of times, the best part of 1000 cycles in total, without any exaggeration. He's since run four or five films through it with good results, and I exposed a roll of Provia 100F transparency in it myself before I sent it to him, which I felt was a fair test of shutter accuracy, which came out well exposed. So I think the silk threads I've used are going to stand up. I also usually place a very small dab of cyanoacrylate on the ends at the second curtain to keep them flush against the ribbons, if needed. It depends a little on exactly where you get the needle inserted though. From memory, the top folds are only 1/8 of an inch long, so if the needle stitches them near the ends, there isn't much to stick up. A tiny spot of cyanoacrylate is always used along the cut ends of the ribbons simply to secure the woven threads and prevent them from unravelling, something the Aki material will easily do if left untreated.

For clarity, these details all apply to the various Contax II cameras I have worked on, but as the ribbon installation is similar on the original, hopefully it will be of some relevance and usefulness to owners working on those, too.

I suspect that just glueing the ribbons in place could work well also if the right glue was used for the job. I stitched mine in place because it was what Zeiss did originally and I figured that I'd simply follow their practice.
Cheers,
Brett
 
I have try to used old roller (with bad central sprig). I have sett some tension (only for ribbons). When I winding the shutter both curtains moving up but it stop at low position. Two hooks on lower curtains didn't reach shutter release "plate" (on the top roller). When I press release both curtains moving down as expected for bad central spring. Anybody have a same issue on top curtain? Why it not move full way up (my ribbons size 100mm)? i have try different speed with same result. Do I need to adjust winding mechanism or it just issue with incorrect tension on lower roller?
 
Deklari said:
Anybody have a same issue on top curtain? Why it not move full way up (my ribbons size 100mm)?
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I would say your ribbons are too short. Can't figure out another cause. It is absolutely true for the ribbons that a little bit too long is not as bad as a little bit too short.

I've always found that one has too try out the curtains first at "B" or "Z". The tension is lowest at that setting. The tension is highest at 1/100 - 1/1000.

When tensioning, the winding knob must make one full turn, 360 degrees.

Erik.
 
Deklari, I didn't have this problem and my ribbons were measured at 100mm but when I remake them I will make them a tiny bit longer, just to be safe.

Erik, I've never quite understood your comment about different tensions. If anything you wind the shutter further on for B/Z so shouldn't the tension actually be greater on that setting?

Hmm, now I think have confused myself completely, surely the tension remains the same across all speeds and it is only the behaviour of the second blind that changes? I cannot see how a different tension can be achieved, the wind is always the same.

Maybe I have just displayed a complete lack of understanding of the camera...
 
Dralowid said:
Erik, I've never quite understood your comment about different tensions. If anything you wind the shutter further on for B/Z so shouldn't the tension actually be greater on that setting?
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Michael, the first version of the Contax I, the model without slow speeds, has only one tension. The models with the slow speeds have four tensions. That is why you have to change the ring with the white and red dots. In fact you are changing gears there, like in a car. In the Contax II and III the "groups" are "automatically" chosen. The Contax I (after v3) has four groups, the Super Nettel three. That is why the slowest speed on a Super Nettel is 1/5 sec. and not 1/2 sec as on the Contax I.
I understand that in the "sports group", the speeds 1/100 - 1/1000, the shutter runs completely free, without any gearing to slow the speed (and the tension) down.

In fact on a Contax I you can also choose "B" or "Z" in the sports group. The shutter opens and closes then quite snappy, wile when making "B"or "Z" in the night group the shutter moves very slow. That makes the Contax I such a joyful toy!

This is explained in the Zeiss Historica article that Brett showed us.

Erik.
 
Erik,

Ah Ha! I see and understand. You are referring to the tensioning of the escapement used for slow speeds and not the tensioning of the shutter rollers.

And, when winding on, the fast speeds offer little resistance because the escapement is not in use but the slow speeds require more effort because one is winding up the escapement.

I'd better re-read the article.

I am at a standstill but my new Kiev roller should arrive early next week. I have not yet carried out any work on the camera because I have been using a Contax II roller to work out fitting and if there are any differences between it and the Kiev one I'd be in trouble.

Michael
 
I've just re-read the article that Brett showed us. I can understand how the slow speed escapement can change the tension or speed of the second blind but do not see how the speed of the first blind can change, it is simply controlled by the roller spring tension AND the effect of the friction clutches. Need to read the article again while watching the camera operate (hopefully!).

Michael
 
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