8mm Forum: Question about 800ft Metal Reel

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Posted by Roger Shunk (Member # 2836) on April 06, 2013, 12:28 PM:

Greetings everyone!
I have an Elmo 1200HD and when I get a film (3-reeler) that is mounted on a 800ft metal reel and go to rewind the film the film
rewinds back lop sided on the reel and the film is very loose.
My take-up reel is an Elmo 800ft plastic reel so do I maybe need to use an
800ft metal reel for the take-up reel when I run a film on a 800ft metal reel? I do have an Elmo 1200ft reel that's aluminum and perhaps I could use that one to?

Thanks for your help,
RS

Posted by Christian Bjorgen (Member # 1780) on April 06, 2013, 04:17 PM:

Sounds very odd... I have the exact same setup, ST1200 with 800 ft Elmo take-up reel in plastic, and it's never been an issue.

In fact, I screened "The Lost World" last night, on 2x800 metal reels, and there was no issue.

Posted by Steve Klare (Member # 12) on April 06, 2013, 05:23 PM:

Maybe since the plastic reel is lighter it has less inertia than the metal one and it speeds up and slows down more easily.

That pulsation of the film during rewind is the the film tension rising and falling and that might lead to an uneven rewind.

Posted by Roger Shunk (Member # 2836) on April 06, 2013, 05:37 PM:

Steve,
Instead of rewinding the film back on the metal reel I rewound it on an Elmo 800ft plastic reel and the film rewound tight like it
normally does and it did not rewind the film lop sided on the plastic reel so it has something to do with the metal reel?

I'm going to try and use a 800ft metal take-up reel with the 800ft metal film reel next time and see if that resolves the problem otherwise it remains a mystery?
RS

Posted by Steve Klare (Member # 12) on April 06, 2013, 05:51 PM:

Maybe it just means there is more going on here than meets the eye.

You have two reels operating at different speeds with film stretched between them that has some elasticity (like a spring). So you have possibilities of all sorts of resonances and maybe some surprising results. (Remember that bridge that shook itself to destruction?) Maybe changing the reels around is enough to alter the equation.

It could keep a Mechanical Engineer fascinated for days, but I'm Electrical and besides, I'm OFF today!

Posted by David Ollerearnshaw (Member # 3296) on April 06, 2013, 05:54 PM:

Could be a slight warp on the reel do you get any noise from the film coming off the reel? It could catch when rewinding till the film pushes the sides of the reel out a little.

Take extra care it will cause scratches on your film.

If you try it the other way round use the problem reel as take up see if it still causes a problem.

Posted by Roger Shunk (Member # 2836) on April 06, 2013, 05:56 PM:

OK Steve thanks for your input enjoy your weekend!
RS

Posted by Steve Klare (Member # 12) on April 06, 2013, 06:02 PM:

Sadly, this is one of the ways I DO! [Wink]

(Thanks!)

Posted by Roger Shunk (Member # 2836) on April 06, 2013, 07:35 PM:

Hi David,
The metal reel is not warped or catching or rubbing on the film so I'm going to just rewind them by hand using my hand cranks! As a last ditch effort I will try and use a metal take up-reel and see if that makes any difference?

It's still a mystery to me why this is happening? [Confused]

Thanks for all your suggestions.
RS

Posted by Pete Richards (Member # 2203) on April 08, 2013, 07:41 AM:

My first guess would be warpage of the reel, it can be very slight and hard to detect if subtle, 2nd geuss would be that the projector hasn't got enough torque to spin the metal reel at the correct speed with the heavier reel.

Posted by David Ollerearnshaw (Member # 3296) on April 08, 2013, 03:28 PM:

I believe the Elmo's projectors, the reels needed a larger diameter hub than some other makes. Is the problem reel small hub?

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