Kiev Pressure Plates

[ruben]

In a past thread started by Dee, I and Noel started to discuss about the pressure plates of the Kievs 4am and 4, deviating from the main issues Dee put there for discussion.

Noel apologized for both of us, while Dee showed great manners in not protesting it but expressing his greetings for new knowledge.

Now for the issue itself. I find we do have an issue to deal with in the pressure plates, that some friend whose name I do not remember now, mentioned it as related to the accuracy of the winding. And there is a lot of logic in the argument.

I said that my Kiev 4 shows a differently designed pressure plate than the 4am, Noel didn't get it, and I promised a picture that is still waiting to be done.

But now after working a lot and finishing my first "prototype" Kiev 4am, I still have problems of frame spacing driving me crazy.

Yet I can contribute to myself and perhaps others too an observation. Beyond the slightly different design in the pressure plates of my 2 mentioned Kievs, there is a practical aspect which may be the key of the story.

The pressure plate of MY kiev 4 looks erected like a sportsman, while the pressure plate of MY kiev 4am looks as if its springs were sick and tired. Accordingly I took out the plate of my 4am and reshaped the springs so they make some real pressure, instead of enjoying the lazyness.

I remember very well that the manual of the preWar Contax gives a strong accent to the propper inserting and transport of the film.

Let's see what happens. First roll now. We will be following this issue.

Cheers,
Ruben

 

[Xmas]

Ruben
The pressure plate will drag the film on take up or rewind and the spring load is a compromise, e.g. CONTAX G cameras have light loadings to allow the motor advance torque to be low but still wind on fast.
When a Kiev back is fitter there is not much room for the spring, so the film should be flat unless it is very stiff, e.g. cold.
If you having spacing problems it is possible to remove tha back and see what the problem is by holding the cassette and wind on spool with one hand and winding with the other hand, if the sprocket drive is not turning properly with the back off, it wont do better with the back on.
Noel

 

[Spyderman]

The pressure plate will drag the film on take up or rewind

not sure if you are familiar with this (in case you are, just ignore this post) but there are 4 rails which guide the film. 2 outer are higher, 2 inner are lower. This allows the pressure plate to be flat on the outer rails, but the film still has space between the inner rails and the pressure plate... Increasing tension of the pressure plate spring shouldn't in any way affect the friction of film when advanced or rewound.

just my 2 cents.

 

[Xmas]

Ondrej
I understand what you say but I suggest the film acquires a natural curl and will drag because of this when it is between the inner rails, and the plate. It reattains the curl on the take up spool and will drag on the way back?
The experiment with the back off is still valid if you can hold the cassette and take up spool resonably. I feel guilty I had not asked Ruben to do this.
Noel

 

[ruben]

Ruben
The pressure plate will drag the film on take up or rewind and the spring load is a compromise, e.g. CONTAX G cameras have light loadings to allow the motor advance torque to be low but still wind on fast.
When a Kiev back is fitter there is not much room for the spring, so the film should be flat unless it is very stiff, e.g. cold.
........

Hi Noel,
Kindly excuss me but I don't uderstand what you are saying here, due both to the contents as the way you express yourself here. Perhaps you can try to extend the explanation, it may be of help.

Cheers,
Ruben

 

[ruben]

not sure if you are familiar with this (in case you are, just ignore this post) but there are 4 rails which guide the film. 2 outer are higher, 2 inner are lower. This allows the pressure plate to be flat on the outer rails, but the film still has space between the inner rails and the pressure plate... Increasing tension of the pressure plate spring shouldn't in any way affect the friction of film when advanced or rewound.

just my 2 cents.

This is exactly what I was thinking when I redressed the springs behind the pressure plate. It is my assumption that with a "tired" pressure plate, the film will disengage from the sprockets.

If this assumption is correct, the test Noel suggest will be of no help.

And the pressure plate springs of my Kiev 4am definitely looked tired and sick.

Cheers,
Ruben

 

[dee]

No pressure then ?

dee

 

[ruben]

Ondrej
I understand what you say but I suggest the film acquires a natural curl and will drag because of this when it is between the inner rails, and the plate. It reattains the curl on the take up spool and will drag on the way back?
The experiment with the back off is still valid if you can hold the cassette and take up spool resonably. I feel guilty I had not asked Ruben to do this.
Noel

Hi Noel,

For when you answer my previous question, I have to inform you that actually I have extracted the fixed spool of my 4am and replaced with a normal original Kiev double slotted detachable spool.

The interesting thing is that after finishing a film, the pattern of the frame spacing continues to be exactly the same. Great spaces (slightly less than half a frame) at the beggining, slowly decreasing until slight overlapping at the end of the film.

The camera has been cleaned and lubricated beforehand, therefore I am looking for the pressure plate and see how a redressed pressure will affect the frame spacing.

Cheers,
Ruben