Film-Tech Forum ARCHIVE: Cnr

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Posted by Antonio Marcheselli (Member # 373) on 10-28-2002, 05:59 AM:

Hi,

How do you call the device on the Cinemeccanica CNR platter that give the right tension at the print after the projector and set the right speed of the platter?
Ok, we have a problem on some of them.
I found the Film-Tech threathing procedure very helpful, I'm using at my 16plex.
I start threading from the top of the projector and when I reach the bottom I pull the film engaging the arm I was speaking above. The problem is that some CNR's arm won't stop in the right position and continues pulling the film, breaking the film in some cases.
Why? What has to be checked?

I'm not sure that I was clear, feel free to ask for clarification!!

Bye
Antonio

Posted by Brad Miller (Member # 2) on 10-28-2002, 06:35 AM:

The Film-Tech threading procedure is to thread bottom up, not top down.

Anyway, pull tension from the platter BEFORE you place it into the holdback sprocket. That way it can't crash, because you can give it that extra foot or two of slack if needed before you put the film into the projector.

Posted by Antonio Marcheselli (Member # 373) on 10-28-2002, 06:46 AM:

Brad,

I know, this is why I precised that I start from the bottom!
I usually "solve" this problem pulling a feet of two of print while tensioning the arm so that if it starts pulling print I have it in my hand and I can give it. I don't like to put the print at the bottom sprocket while it is tensioned.
But is it a normal thing? Why some platter has this behaviour and others don't?

To explain better the gravity of the situation I had a stop of a projector yesterday at projector start. The print was out of the tensioning arm. I put the print correctly and I rotate manually the platter to start the tensioning arm. The print immediately came out of the arm again.
Result: the iron plate that keep the three rollers (next to the tensioning arm) was BENDED!!! The platter has pull so hard that has bended the plate!!

I can't believe that this is a normal situation. We have 16 CNR, just few of them has this problems.

Any suggestions will be helpful!

Bye
Antonio

Posted by Michael Schaffer (Member # 1204) on 10-28-2002, 08:25 AM:

Solution: Get Kinoton platters (not very helpful, probably

). Seriously, there has to be a potentiometer which translates the position of the arm into platter speed. Look for it and change it.

Posted by Antonio Marcheselli (Member # 373) on 10-28-2002, 08:59 AM:

Michael,

Yes, it is not very helpful but... I agree with you!!

The problem is that I believe that the potentiometers are working correctly. The arms stop the platter all at the same position. But some platters continues rotating just for inertia pulling the film.

Some others seems to have a motor brake...

Antonio

Posted by Ben Wales (Member # 92) on 10-28-2002, 02:36 PM:

Although there is about 3 seperate adjustments (I recall) could be made on a CNR, on the Take-Up arm under each plate we measured 500mm from the Arm to the Centre post and the plate should stop rotating at this point.