Correct procedure for platter loading/unloading

[Neal Scanlan]

I wanted to ask if anyone could advise me on the correct procedure for loading and unloading onto a platter.

I have a Christie AW3R platter and an MU table.

At the moment when loading a film I remove the belt from the MU table pulley and apply gentle resistance to the reel as the film winds onto the platter. I do this because, with the belt attached, there is considerable force required to rotate the pulley, belt, and motor spindle — more than seems ‘right’ or kind to the film. The pulley and motor spindle are free running and I can detect no mechanical resistance that would cause this resistance.

When unloading the film from the platter, I also notice a lot of resistance when rotating the platter, especially after the first four reels have been removed and the film diameter is much smaller. Although not completely resolved I have noticed that when the correct platter is switched on, there is less resistance. Is back EMF at play here?
On the last reels, I tend to hold the motor drive away from the platter (with a small wedge) and apply light finger pressure to the top surface of the platter to keep the tension within limits.

I’m not sure whether this approach is how the system is intended to be used, so any clarity or advice would be much appreciated.

[Marco Giustini]

I have zero experience with the AW3 but the user manual is available here: https://www.film-tech.com/warehouse/manuals/CHRAW3R.pdf

I see you have to select the platter on the AW3 itself and correctly set the switches on the MUT. Page 6-1

I'm sure others will be able to help further.

[Tony Bandiera Jr]

I wanted to ask if anyone could advise me on the correct procedure for loading and unloading onto a platter.

I have a Christie AW3R platter and an MU table.

At the moment when loading a film I remove the belt from the MU table pulley and apply gentle resistance to the reel as the film winds onto the platter. I do this because, with the belt attached, there is considerable force required to rotate the pulley, belt, and motor spindle — more than seems ‘right’ or kind to the film. The pulley and motor spindle are free running and I can detect no mechanical resistance that would cause this resistance.

When unloading the film from the platter, I also notice a lot of resistance when rotating the platter, especially after the first four reels have been removed and the film diameter is much smaller. Although not completely resolved I have noticed that when the correct platter is switched on, there is less resistance. Is back EMF at play here?
On the last reels, I tend to hold the motor drive away from the platter (with a small wedge) and apply light finger pressure to the top surface of the platter to keep the tension within limits.

I’m not sure whether this approach is how the system is intended to be used, so any clarity or advice would be much appreciated.

DO NOT EVER remove the drive belt on the mut!! The back tension provided by the motor is the correct amount and IS NOT EXCESSIVE!! Your method of applying resistance to the reel WILL result in uneven tension on the film pack and as you add reels you WILL start rubbing the film layers together!! And if you try to turn the MUT shaft by hand without a reel of course it will feel tight. The diameter of the film and core of the reel through the principles of mechanical advantage will drop the tension considerably.

And yes, you must use the proper platter deck selection on build up AND teardown, as the control in the MUT applies the proper back voltage to the platter deck to maintain a smooth wind with enough tension to prevent the film spilling as you get the end of the reels.

And again, DO NOT HOLD THE MOTOR DRIVE AWAY FROM THE PLATTER!!! AND AGAIN, YOUR "LIGHT FINGER PRESSURE" WILL RESULT IN UNEVEN WIND ON THE REEL WHICH WILL DAMAGE THE FILM.

I am sorry to be so harsh, but you have manged to somehow overthink the process to the absolute limits, guaranteed to cause maximum damage to the film. And you are wasting your own time in the process.

Let the MUT and platter work together as designed and keep your paws off of everything else.

[Randy Stankey]

When I was servicing theaters for Cinemark, one of the biggest problems I saw was from people not setting the platter controls correctly before breaking down. Be it Christie, SPECO or what-have-you, the right buttons and switches must be set or else you won't be able to break down, properly. The only platter I know that free-wheels during breakdown is the Potts Alpha but that's another kettle of fish.

If you don't set the switches right, you are likely to end up with cinch marks on your film. Either the platter gives too much resistance or the motor on the MUT pulls too hard or a combination of the two. When you start the motor, the film gets pulled too hard and the windings of film rub together. You can ruin an entire print, that way, in about nine seconds!

If you put something behind the platter motor to wedge it out of the way, you take the chance of dumping the print on the floor. The platter can spin out of control and, when you go to stop it, disaster strikes! Even if you don't dump the print, using your hand as a brake causes uneven tension or, if there is a burr on the edge of the platter, you can end up with a bloody hand. (You don't have to ask me how I know that!) Finally, if you forget to take that wedge out of the platter before you start a movie, it'll be brain wrap city!

I would regularly get calls from theaters and, when I went there, I'd find scratched prints, belts taken off, wedges stuck in places where they don't belong, drive rollers with grooves worn into them and all sorts of other odd things. It was all because people refused to do things the right way.

Just set the controls like it says in the manual and more than 90% of the time you'll have zero problems!

[Neal Scanlan]

Hi Tony,

Harsh is fine, clarification is exactly what I’m seeking.

The reason I deviated from the approach you describe is that many of the films I receive have not been wound with enough tension to prevent them “winding up” on the reel when the platter feed is engaged. Clearly, I need to rewind these films on the rewind table first and achieve much tighter tension to avoid any film-to-film slippage on the reel during the first load from the MUT to the platter.

[Jim Cassedy]

While Tony is correct, if you go 'by the book' - - in at least one theater I used to occasionally
help out at, there was no other way to load/unload the platter (AW3) and shipping reels without
removing the MUT belt and/or wedging the platter motor. In a perfect world and with reasonably
well kept equipment, it shouldn't be necessary, but not disengaging the belt or platter-puck caused
far more damage to film at that location than doing it 'the right way'. (I know this because I tried
doing it the correct way once, and immediately saw that it just wasn't going to work well.)

> One other suggestion I'd make is that if you are at a location that doesn't run film very often,
I'd stick wedges in the platter drive mechanism to to keep the rubber pucks from forming flat spots.
I know several locations that do this. The smart one also has made 'flags' out of an old red scarf
that hang from the wedges so that even a dummy could easily see them before attempting to use
the platters.

[Marco Giustini]

not having been a Christie user, is there any chance that some adjustment need to be done to the AW3? I was wondering: how does the system know what the correct tension is, considering it will change depending on how full the platter/reel are? I'd imagine it's a very simple mechanism. The cinemeccanica platter I used was super simple: either the platter or the MUT platter were fully disconnected and tension relied on the projectionist

At some point I saw a quite clumsy attempt of making a "brake" for the platter which consisted into an electromagnet pushing a rubber thing against the bottom of the spinning platter: it was 100% useless.

I'd imagine Kinoton had a more sophisticated mechanism so I'm curious to hear how the AW3 worked.

[Josh Jones]

There is a manual with schematics in the warehouse...

The only time I ever did the wedge trick (I used a screwdriver) was when running very old brittle acetate prints. Never had an issue with poly prints. AS Tony mentioned, you greatly increase the risk of cinch damage by using manual tension, or trying to load films that are not wound tight enough.

[Marco Giustini]

more an exploded view than schematics if it's the one I found.

[Brad Miller]

There was one generation of MUT motors that actually did exert way too much backtension when loading, as in it compressed the center ring. It's possible Neal has one of those. It's also possible the film reels he is trying to load are just wound so loosely that winding onto the platter with almost no backtension may be the only way to keep from cinch scratching the reels during the unwinding of them. It is ok to load with no or very little backtension by removing the MUT belt, but he has to be very cautious to start VERY slowly and to stop very slowly as well. Even if he overshoots it and has to pull the tail back off of the platter, that pulling backwards of the tail leader could cause the layers of film on the platter to slip against each other and cause cinch scratching. This is just one of those scenarios where he will have to make a judgment call. Also note the print CANNOT be moved until it's been ran once off of that platter to prevent high risk of scratching due to it being wound so loose.

If the belt is removed from the MUT motor though, remember there is a rough side and a smooth side. The ROUGH side must go back onto the pulleys!

Breakdown is another entirely different thing. The motor should be left ENGAGED and not propped away from being able to make contact with the edge of the deck. On the AW3, the MUT actually WILL break down if you forget to punch that deck's makeup button, but that will cause damage to the print. Whether building or breaking down, that deck's makeup button on the platter tree's column MUST BE ENGAGED!!! Doing so drops the backtension resistance down to a proper point for a tightwind, suitable for shipping.

The only exception to that is if the bearing on the axle is not lubricated or is failing, there could be too much backtension even with that platter deck's makeup button engaged when you get to reel 1 or possibly reel 1 and 2. If the platter is properly maintained though, that will not be an issue. Breaking down by manually adding a bit of tension or letting it free-spin is begging for cinch scratches to occur and if they don't occur during breakdown, you can damn well bet they will occur during shipping back to the film depot from all of the shuffling around due to a loose wind.

Also regardless of everything...never and I do mean NEVER use the "brake" feature on the MUT. It was a terrible design from the get-go and will give you a 99% chance of cinch scratching or mangling film to some degree if you use it.

[Neal Scanlan]

To Brad’s point, once the film has been loaded onto the platter I do run It at least once before a show as this puts it back on the next deck perfectly. My feelings are a little towards the ‘black art’ as there is even some difference in tension between the decks. All your comments are extremely useful in helping me achieving good practice and gaining confidence. Preservation of the condition of the film being the absolute objective.

Another thought. Selecting the correct deck button (reducing the back tension resistance in the motor) is required on the platter does the load switch on the MUT do the same for it’s motor. Could this circuitry be faulty and therefore not reducing the resistance? The pulley ratio is significant and the motor spindle is of a very small diameter.

[Randy Stankey]

While you certainly can run a print right after building but, IMO, best practice is to run it through, once, before your first go-show. It makes sure that film is wound evenly and it gives you a chance to check for problems like bad splices (which might not be yours) or damaged film that you might have missed.

I have run prints right off the build but I absolutely prefer to have at least one run before an audience sees it.

[Brad Miller]

Another thought. Selecting the correct deck button (reducing the back tension resistance in the motor) is required on the platter does the load switch on the MUT do the same for it’s motor. Could this circuitry be faulty and therefore not reducing the resistance? The pulley ratio is significant and the motor spindle is of a very small diameter.

There is no difference. It sounds like you just got that one vintage of MUT motors that creates too much resistance when loading.

[Ryan Gallagher]

I think it is safe to assume you only have the one projector? But if film preservation is the goal, consider a second and switch to change over? Most prints I get from archives and studios have strict no plattering rules. Even newly struck new release prints are basically studio archives because so few are made.