Film-Tech Forum ARCHIVE: Who was the first to interlock?

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Posted by James Westbrook (Member # 3690) on 05-24-2006, 10:38 PM:

I used the search function and could not find a simular thread...
One of the theatre managers here in Lubbock years ago claimed that an employee of an area theatre chain "invented" interlock, simular to but not quite as extreem as what Brad done in Colorado. This was done between 2 auditoriums which were not running on platters but on big reel film transports. According to the legend, the employee was lacking in forsight and didn't get a patent on this. (If it was possible to patent this...).
This was during the era of the mini-cinema, late 60's or early 70's, and platters were not common around here then. This owner preferred Century heads, remanufactured, and the transports he used was either some odd-ball manufacture which I can find nothing on or possibly "home-made", as described by one of his former employees.
I am leaning on the side of "urban legend" as these theatres didn't have automation which dimmed lights or the like but had some kind of failsafe switching to shut off the projector when the film ran out or broke. Wiring two motors to start at once can't be too hard of a trick.
Can any of y'all recollect when interlocking between 2 screens first started?

Posted by David Kilderry (Member # 142) on 05-25-2006, 05:36 AM:

Well, I can't claim doing it that long ago, but we first did it at Hoyts 8 Chadstone here in 1986 on Crocodile Dundee.

I worked with another projectionist who said he interlocked back in the late 1970's at the old Frankston twin. Later when I worked there the rollers were still set up for it even though it was used rarely in later days.

I'm sure there are others here who can go back further than these examples???

David

Posted by Mitchell Dvoskin (Member # 751) on 05-25-2006, 08:48 AM:

Interlocking was common here in NJ in the early 1970's. The technology that allows this to work (selsyn motors) was installed in many theatres back in the 1950's for dual projector 3D.

Posted by Steve Guttag (Member # 268) on 05-25-2006, 09:09 AM:

Oh, interlocking was done without selsyn or any other sync motor in the 70s. I don't know of any interlocks in this area (of running one print in multiple screens via platter or large reel-transport) back into the 1960s...but definately in the 1970s.

Back when projector soundhead had brakes, we used to cut up foam rubber and squish it in just enough to have the fast motor run at the same speed as the slower motor. The film accummulators were more of a home made thing too. Typically just two rollers mounted to the ceiling and one roller with weight added. A box with foam was placed under the roller to catch it when it dropped.

Starting the two either involved an assistant with a "1-2-3-GO" or an automation that took 7 or so seconds before it started the motor so the operator could get the manual motor switches of the other theatre or merely starting with the weight all of the way down and then booking over to the other screen in time. A wise person puts plenty of extra leader to ensure that all was stablized before the audience knew the show was starting.

I think my first "Full complex" interlock on one print was Friday the 13th at the old K-B Cerberus...it was only a triple but in triangular formation. I don't beleve ANY extra rollers were used to accomplish the film path either. It had SPECO platters (Drive-Ins in those days)..one 4-deck and one 3-deck. The take-up elevators served as the accummulators and the top-deck take-up roller (the one that swivals, not the one on the elevator system) allowed us to shoot the film over to the next theatre.

I remember the thought of a Georgetown house going down on a triple interlock on a horror film for a midnight show was much scarier than the film itself!

[ 05-25-2006, 01:29 PM: Message edited by: Steve Guttag ]

Posted by Ken Russell (Member # 2491) on 05-25-2006, 09:17 AM:

The best I can do is 1977. I picked up a position at the Briarwood 6 in Kansas City. There were 3 booths presenting on two screens each. Screens one and two was the only booth with a fairly matched set of platters. The other two were mixtures of almost everything including a platter driven by a glorified vacuum cleaner and a changeover system running 6k reels. In the "matched" booth a makeshift acumulater was set up with rollers on the ceiling. The automation, if you could call it that, nor the motors were in any way connected. To get it started required some acrobatics. When setting up very little loop was in the "acumulater". Using the manual motor switches you would start the feed side projector first then the take up one, hopefully before the film reached the floor. Then each automation was told to start which struck the lamps, opened the dowsers, dimmed the lights and so on. Since the motors were not in any way synchronized the setup had to be watched. If the film began to get too tight the take up side was slowed. If things were not too bad at the moment a rag was pushed against the knob on the motor shaft. Yes, I still have all my fingers but sometimes I wonder how. If the situation was getting really bad the motor switch was cycled to let things even out. If the film was headed for the floor the feed side projector got the treatment.

I didn't set this system up so I am not sure how long it was around before I came along. The system did work, though. I am guessing that the "trick" has been around since the first multi-screen non-changeover house came to be.

Ken

Posted by Brad Miller (Member # 2) on 05-25-2006, 01:47 PM:

I don't know if anyone has interlocked a changeover setup, but it really wouldn't be difficult at all...particularly if they were both driven by a frame accurate changeover system. You just have to make sure however many frames are between the two left projectors are exactly the same as the number of frames between the two right projectors.

Posted by Louis Bornwasser (Member # 3063) on 05-25-2006, 02:26 PM:

Well, it would be a toss up between these Louisville area theatres: Alpha 1, Alpha 2, Alpha 3, Alpha 4, the Village 8: all were interlocked prior to 1975. All were Century with Selsyn motors and AW4 platters (4 deck AW-2's) Kelmar already made a control box to sequence the AM-3 and Maxi series automation. (Only the Village survives.)

Locally interlock was "normal" by 1976, especially for school shows. Louis

Posted by Robert Throop (Member # 61) on 05-26-2006, 06:53 AM:

Many years ago I knew Walter Hewson who was a tech in the SLC area. He told me about a twin with Cinemecanica V-18's that interlocked. He told me that the operator would watch the size of the loop between the two machines and brake the appropriate projector to keep the loop size constant. This was in the very early seventies.
Bob

Posted by David Graham Rose (Member # 1450) on 05-26-2006, 01:27 PM:

Greetings

In reply to the subject, there is evidence in the Good Book that Moses first interlocked Arc 1 & Arc 2 with selsyn motors, to exhibit films to all the animals on his boat.

Regards

David

Posted by David Graham Rose (Member # 1450) on 05-30-2006, 01:58 PM:

Greetings All

I have just unearthed an old treasure trove from the rear of my garden shed and have found a single selsyn interlock motor. I can not fathom out why anyone should keep a single interlock motor. I mean, what use is it? What will it lock to? Thin air? Just as useful as a singlr telephone don't you think?

From Cambridge

David

Posted by Louis Bornwasser (Member # 3063) on 05-30-2006, 02:26 PM:

Likely as good as one hand clapping......probably from old 3D. Louis

Posted by David Graham Rose (Member # 1450) on 06-06-2006, 05:50 AM:

Greetings Louis

Why would you need to clap a hand in order to run 3D? I've run plenty of 3D and have either used anaglyph method or polarised with a silver screen.

Yours

David