Film-Tech Forum ARCHIVE: Building-Up Too Fast, Too Tight -- Christie AW3-R and MUT

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Posted by Manny Knowles (Member # 1171) on 03-06-2003, 04:38 PM:

I had a problem at a theatre where movies were building too tightly. They are using Christie AW3-R platter systems.

I observed a projectionist building a movie and the platter was going way too fast, so I told him to slow it down to about 50%. He told me that he was already at 50% on the dial.

I adjusted the little trimpot on the MUT speed control (all the way down) and that helped a great deal.

Is there some way that I can really cut the pace of this system even further? Human nature being what it is, I am sure that someone will take to building movies at 100% Max Speed and I'd like to work this out in such a way that a person like that won't screw up a print.

Does anybody have recommendations as to how many RPM we should get on the platter deck when the MUT dial is at 100% Max Speed?

Posted by Scott D. Neff (Member # 185) on 03-06-2003, 05:43 PM:

That's the first time I've ever heard of an AW3 building up too tightly. I used to have the exact opposite problem. I'd consider myself lucky if I had a Christie platter that built up tight enough.

Sorry this response didn't have any useful suggestions. [Roll Eyes]

Posted by Manny Knowles (Member # 1171) on 03-06-2003, 07:17 PM:

quote:
Sorry this response didn't have any useful suggestions.

I'm sorry too.

Anyone else?

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-06-2003, 09:09 PM:

It's not so much the speed you have to worry about, it's the back tension. Make sure the supply reel's spindle shaft isn't being restricted.

Posted by John Westlund (Member # 913) on 03-06-2003, 09:39 PM:

Just a guess but possibly the make up table belt too tight?

Posted by Mark Maxwell (Member # 1355) on 03-06-2003, 10:56 PM:

At my first theater that I did projection at, we had a mutt that restricted the spin of the reel. My manager suggested building up slow, but it was still so tight that I had to bang on the ring from below the platter with a hammer to get it out. At another theater, I had to build up Planet of the Apea at full speed because we got it thirty minuts befor showtime. It wasn't tight at all, and luckily for me there were no scraches from the buildup.

Posted by Brad Miller (Member # 2) on 03-07-2003, 06:07 AM:

There are a couple of different motors that can be used in the Christie MUT. The older style builds somewhat loose, the newer style will "bust ass" at speed and wind plenty tight enough to move the print without running it through the projector once.

Personally since I always train for people to load the film where it will play it's first showing, I prefer the older style motor for building (well ok, I really prefer using a Goldberg platter reel for building) and the newer style for breakdown. Just don't run that breakdown much past 2:00 (and that's if you know have the know-how to do it and now screw things up at that kind of speed.)

Oh, and if you choose to alter the speed setting on the potentiometer board, do so with it UNPLUGGED! You can zap things you don't want to get zapped. [Eek!]

Posted by Manny Knowles (Member # 1171) on 10-25-2003, 12:03 AM:

This problem remains unsolved. Build-ups are so tight that it is usually quite difficult to remove the hub.

Reducing speed did not really help. One would have to use a ridiculously low speed and that's simply not practical.

Perhaps Bevan can point me in the right direction?

All my MUT's have the larger replacement motors. Belt tension doesn't seem to be an issue.

Posted by Brad Miller (Member # 2) on 10-25-2003, 01:01 AM:

How hard is it to spin an empty reel by hand on the mut set for "loading"?

Posted by Manny Knowles (Member # 1171) on 10-25-2003, 10:37 AM:

Brad I will check that when I return. I'm still in Florida. [Big Grin]

Posted by Matt Zeiner (Member # 1914) on 10-25-2003, 02:40 PM:

quote:
How hard is it to spin an empty reel by hand on the mut set for "loading"?

Not too sure, but Brad sounds like he's in the ballpark. I would check the belt tension - could be overtightened putting drag on the film. Make sure the pulleys are aligned. Check the motor bearings, the shaft and its associated bearings, too. There's no clutch so those are the only things in the system that will affect the tension of the wind.

Posted by Bevan Wright (Member # 1884) on 10-25-2003, 04:14 PM:

The new 'larger' motor puts more tension on the belt. Try changing the angle that the bracket holds the motor (more vertical), thus transfering more of the motor weight load from the belt onto the support bracket.

Posted by Manny Knowles (Member # 1171) on 10-25-2003, 10:16 PM:

Okay, thanks.

This makes a lot of sense to me because I never had this problem with the old motors -- but everyone *swore* the new motor was "just as good."

I'll follow up when I get home.

Posted by Dave Callaghan (Member # 1544) on 11-02-2003, 05:16 PM:

I am not familiar with the Christie MUT, but I did have a problem with a SPECO platter MUT that resulted in EXTREMELY tight make-up on a 70mm print of Brainstorm.

The cause of the "problem" was that the spindle was connected to the MUT motor. For make-up, all you need is a clutch to maintain tension. The issue with this design incorporating the motor for make-up and breakdown on the same spindle is that the motor is driven/energized during make-up, and it turns in a specific direction. So, it matters which way the film comes off of the reel. If the reel turns in the same direction as the motor rotation, the wind will be reasonable. However, if the reel turns against the motor rotation, the wind will be impossibly tight. The motor actually pulls the film tight, and the effect is worse the faster you load, since the motor speed increases as you advance the speed control.

Posted by Manny Knowles (Member # 1171) on 12-05-2003, 04:13 AM:

I've been meaning to followup on this...

I built up a number of movies for a special event and did not have the "tight build-up" problem.

What did I do differently from the projectionists?

I built the print onto 6000' reels at the rewind table before going over to the MUT.

I thought EVERYONE did it that way!

The larger (heavier) reel spins more easily, which is extremely beneficial when transferring those first few reels onto the hub-ring-thing.

I will leave it to the scientist types among us to explain exactly why this is so.

Posted by John Pytlak (Member # 331) on 12-05-2003, 07:56 AM:

Manny wrote:

quote:
What did I do differently from the projectionists?

I built the print onto 6000' reels at the rewind table before going over to the MUT.

I thought EVERYONE did it that way!

Inspecting the print on a rewind bench as you build heads-out 6000-foot reels to load onto the platter is the preferred way of operating. [Smile]

Proper print inspection on most make-up tables (MUT) is awkward at best.

Posted by Kevin Wale (Member # 1851) on 12-05-2003, 11:35 AM:

In Guymon we had one of the newer motors and in Woodward we had one of the older motors. The newer motor does have more of a tendancy to wrap too tight and for a while the owner was so paranoid about it that he made everyone building up put something in the ring so it would only go so tight.

I just slowed down. Actually, I never built up fast enough to make it too tight anyway. But, I had everyone slow down and we eliminated the need for the wedge factor.

I found that the way the tension rollers clamp on to the pole helps keep me from going too fast anyway because you'll pull those things around and have a big ol mess.