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Author Topic: Static problems?
Joe Redifer
You need a beating today

Posts: 12859
From: Denver, Colorado
Registered: May 99


 - posted 08-04-1999 05:46 PM      Profile for Joe Redifer   Author's Homepage   Email Joe Redifer   Send New Private Message       Edit/Delete Post 
Lately I have been having at my theatre what appears to be static problems, but I am not entirely sure. The symptoms are exactly that of a static infested print: erratic feed-out and the tail comes untucked. However I have noticed this only on the last reel or two of a given print. A single pass of FilmGuard will cure this, but I have found some other interesting "cures" as well.

The first thing I tried was to wrap what I like to call a "filmbelt" around the print, which eliminates the tail tuck altogether. The filmbelt is a piece of film (I use blank film that has been 'erased' and can be obtained from Kodak... at least that's what the film itself says) that is taped to itself and stays on the platter deck as the film ends. It can then be slid over the top of the print easilly for the next show. When I use this, sometimes the static seems to go away altogether for some reason, as if the tail tuck was causing the erratic feedout (I wouldn't be surprised if it were). Sometimes the tuck can interfere as the film is being pulled toward the brain, as the film must be pulled over the tail and can, in my experience, initiate improper feed. This will cause the print to slide all over, the print will become misshapen, and the tail to become untucked. Not good. The filmbelt will prevent the tuck from initiating any problems. If the tuck itself is not the problem, then the filmbelt will prevent the film from sliding all over the platter (in my experience). I do not ever recommend suction cups as they are pretty much worthless, and the filmbelt does a much better job. If you insist on using suction cups, then I recommend TECO pucks, which are quicker and easier to use, and far more effective in my opinion.

A friend of mine at a different theatre that also uses Christie platters will put a small trailer core in the brain after the first reel has passed. This will prevent the brain from reaching 100% and throwing the print. This should be done if the platter is not timed properly. He uses this in combination with the filmbelt. I find that if you time your platters properly, you do not need to do this. But if you feel that your platter is not timed properly and "bursts" to full speed when slowly moving the throttle from 0% to 100%, then you may want to give this a try.

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000


 - posted 08-05-1999 08:04 AM      Profile for John Pytlak   Author's Homepage   Email John Pytlak   Send New Private Message       Edit/Delete Post 
"Platter Fling" usually occurs near the end of the movie, when the feed roll becomes non-circular, or gets off center. Platter clips or "Stick-A-Poos" should always be used to restrain the roll. I agree that "tail tucks" lift the roll from the platter surface, and may make the roll more prone to slide.

I like the idea of a thick film band around the roll. Another idea is to restrain the outside of the feed roll with a solid hoop or ring. A plastic "Hula Hoop" may work for shorter features. Or a restraining ring could be made out of a section of heavy garden hose or flexible plastic pipe --- could even make the diameter adjustable by linking the two ends into a hoop with a smaller diameter hose. Still need to attach the restraining hoop to the platter surface, which could be done with the suction cup clips or "Stick-A-Poos".

------------------
John Pytlak

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Joe Redifer
You need a beating today

Posts: 12859
From: Denver, Colorado
Registered: May 99


 - posted 08-05-1999 02:12 PM      Profile for Joe Redifer   Author's Homepage   Email Joe Redifer   Send New Private Message       Edit/Delete Post 
The only time we ever use suction cups or TECO pucks (stick-a-poo's LOL) is after we move a print for it's first run if the tail tuck is insecure. Otherwise there isn't any need. If anyone is having serious problems with prints being slung on a regular basis, get somebody who knows what they are doing in to time the platters (or get better platters). Regardless of my Christie vs. Strong platter arguments, I still think Christie is a strong #2.

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Trevor Bailey
Expert Film Handler

Posts: 113
From: Woonsocket, RI
Registered: Jun 99


 - posted 08-08-1999 05:10 PM      Profile for Trevor Bailey   Author's Homepage   Email Trevor Bailey   Send New Private Message       Edit/Delete Post 
I have seen a "film retaining ring" being used at several National Amusements theaters. It appears to be strips of metal about an inch wide and a couple of feet long, bolted together to form a hoop. Along the edge are attached a dozen or so short bungie cords that have a metal s-hook on the the other end. The hoop is placed on the deck, the hooks are looped over the edge of the deck and no more prints sliding off the deck. I believe they are making them in house in the Massachusetts area. They seem to work quite well.

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Mathew Molloy
Master Film Handler

Posts: 357
From: The Santa Cruz Mountains
Registered: Nov 2000


 - posted 01-28-2002 11:13 PM      Profile for Mathew Molloy   Email Mathew Molloy   Send New Private Message       Edit/Delete Post 
We're taking over a theatre that has horrible static problems. Funny thing is the problem starts immediately at the change from reel 6 to 7 and lasts thru reel 8. Threw the print of Ali last week - first time that's happened to me in the 7 years I've been doing this.

Anyway, I did find out that if I go up and let the edge of a long screwdriver glide along the edge of the last reels for a couple seconds the static goes away!

The Christie platter is horribly scratched and tarnished and I'm hoping the static problem will go away once I use the sanding tips provided on this site. We will be getting a Kelmar cleaner and FilmGuard in a couple weeks as well. I just thought the screwdriver thing was interesting...

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000


 - posted 01-29-2002 05:55 AM      Profile for John Pytlak   Author's Homepage   Email John Pytlak   Send New Private Message       Edit/Delete Post 
Mathew Molloy said: "Anyway, I did find out that if I go up and let the edge of a long screwdriver glide along the edge of the last reels for a couple seconds the static goes away!"

Sounds like the print has no path to ground through the platter, so static is able to build up. Touching the film edge with the screwdriver is providing a path to ground, allowing the static to discharge. Even though the print film has a conductive backside layer, the static must have a path to ground, or it can build up and cause inter-layer sticking.

You should definitely be sure the platter surface is clean and free of non-conductive oxide buildup. Be sure the platter frame is well grounded. Treat the surface of the platter and any rollers with a conductive antistat like Static Guard or Endust for Electronics. There are also conductive brushes on the market that gently contact the film while running to assure a path to ground for any static buildup:
Kinetronics Anti-Static Brushes

The last reels of longer movies tend to have the most problems with "static cling", since the film is pulling away at such a shallow angle as the feed point gets further from the center. That is why longer movies like "Ali" and "Lord of the Rings" seem to have more static problems. Additional things to try are measuring and maintaining the proper relative humidity (50 to 60 percent RH is best), winding the film with the opposite orientation (so the natural curl of the film helps resist pulling-in), checking platter timing and leveling, and better restraining of the outside of the roll to prevent sliding and "static fling".
------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion


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Jon Bartow
Master Film Handler

Posts: 287
From: Massachusetts
Registered: Nov 1999


 - posted 01-29-2002 11:10 AM      Profile for Jon Bartow   Email Jon Bartow   Send New Private Message       Edit/Delete Post 
I too have seen the metal rings at NA theaters out here (Hi Trevor, How's it going in Mass.?). Some have been made in Mass, some in-house in Louisville and a variation is being made here in MI.
The Variation:
3/16" aluminum (The bungee cord version uses 1/8") 1" wide strip approx 12' long (I don't remember the exact measurement) bent very carefully into a circle and the end flush bolted together with a short piece of aluminum(the flush/countersunk bolt head on the inside of the loop) then three 2" wide by about 9" long pieces of the 3/16" aluminum (or some other stiffer metal) are bent with two 90deg angles (looks like stairs). These are bolted evenly spaced around the outside edge with the end of the 9" pieces hanging over the edge of the platter deck. However the ring is sized so that the pieces hanging over the edge are just a liitle bit short, this makes it so that there is some tension on the ring and it can't go anywhere.
Oh and the bit of metal hanging over the edge of the deck is bent inwards at the bottom to prevent it from sliding upwards.
Of course I try to keep their platters all timed correctly but because they use the rings on almost all of their platters if there ever is a problem they don't get thrown prints.
This version has the advantages of no little s-hooks to catch on your clothing (or skin ) and is much easier to move from deck to deck.
One theater even made a 70mm version using 3" wide aluminum.


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Joseph Pandolfi
Expert Film Handler

Posts: 213
From: Milford, CT.
Registered: Nov 1999


 - posted 01-30-2002 05:30 PM      Profile for Joseph Pandolfi   Email Joseph Pandolfi   Send New Private Message       Edit/Delete Post 
Trevor, we use them here all the time at our NA theatre in Conn. We have the first made Christie platters with the fixed heads. So to move prints around, we take them up on a donut move them and then we would attach the hoops on for the first show because the donuts are slippery. Joe with those platters we have. We had serious problems with them a couple years back with thrown prints. To correct this we did sand down all our platters to a very fine grooved surface. Then we took all our sticky-poos and threw them away, because we would be picking them off the floor anyway after a thrown print. Then we got a large chunk of clear film and cut them into 10 foot sections and use them as film bands. And of course last but not least FILM-GUARD. For over a year and a half we only had two problems. One was the projectionist fault for tail-tuckin on a freshly built print without FG and the second was a brain-wrap from a sticky splice.


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