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Author
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Topic: Threading Loops in a Simplex 35
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John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 02-06-2001 10:47 AM
The lower loop is easy to specify: Standard SMPTE 40 specifies the displacement of the analog soundtrack from the corresponding picture frame is 21 frames +/- 1/2 frame. If you thread the film up with exactly this distance between the aperture and sound pickup, it will be in sync if you are right next to the loudspeaker(s). But since sound travels about 50 feet in 1/24 second, to be in sync for an audience member seated 50 feet from the screen in the center of the theatre, you would normally "pull up" the sound by one frame. In other words, for most indoor theatres, 20 frames between the picture aperture and analog sound pickup is the proper size for the lower loop. In a really large theatre (100 foot seating distance), it might be as small as 19 frames.The upper loop should be large enough to not pull against any gate component, regardless of the framing position, yet small enough so as not to "slap" against any projector component. Many projector manuals (see the "MANUALS" section of Film-Tech) have threading diagrams illustrating the recommended loop size. Or, with scrap film (e.g., old trailers), try a variety of upper loop sizes and carefully watch the film motion as you move the framing between its extremes with the projector running. You want to use a loop size that runs quietly, yet does NOT come into contact with any part of the gate or projector, causing scratches. BTW, always try to keep the framing adjustment at the center of its travel, but recognize that framing the picture while it is running will change the loop sizes, and the loops need to take this into account. ------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
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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Randy Stankey
Film God
Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99
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posted 02-06-2001 12:01 PM
What "flavor" of Simplex do you have? There are 3 major types. (and several sub-types) It helps us to know this. Just look on the side of the projector there should be a label. The model number should be something like, "PR-1050" or "PR-`1060". It could say "Millennium" instead of "PR-2000" as well. Most Simplexes thread pretty much the same, thoughHere's what I teach all my new guys: Center the framing knob. Either turn the framing handle till the word "FRAME" is right side up and level or look at the intermittent and notice there's a line engraved into the side of the bearing arm. Turn the knob until that line is roughly vertical. Time the projector. On Simplex, this is a piece of cake. Look at that line I just told you about. There's a silver "ring" that has four lines engraved into it as well. Just turn the flywheel until the marks line up. Put the film into the gate. Line up a frame with the aperture and seat the film onto the intermittent sprocket. Close the gate. Make your upper loop as tall as the upper sprocket. Some people say, "Use two fingers to make the loop", but that doesn't really work on a Simplex. I find the visual reference works better. If you DON'T have a digital sound reader on top of the projector this loop isn't critical. Just like John P. said. Make it so it doesn't touch anything or pull against the gate. If you DO have digital sound you have to make this exactly right. Make the bottom loop. I tell people to put their finger in the loop and pull it down. When your finger lines up with the bolt in the middle of the sprocket you have it right. Thread the sound head. There's that tension roller at the bottom, right of the compartment. It's usually silver. Pull the film over the sound sprocket until that's tight against it's stop. Then back off 3 sprocket holes. If you want, you can set this and then take a magic marker and make a reference line. Next time just line up the edge of the swiveling bracket with the mark. Finally, when you're done, turn the projector over by hand by a few frames. Watch the film go through the projector and listen for the sound of film "crunching". Fix any mistakes now! This is the ONE step that people don't do that could have saved a LOT of trouble! Absolutely! Positively! Get into the habit of checking your projector right now! After a while you won't even know you're doing it because it's so automatic. It's a LOT harder to develop the habit later on. You wil have a LOT less trouble learning projectors if you find your mistakes before you try to start the show!
Hope this helps! Good luck!
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John Keegan
Film Handler
Posts: 26
From: Trevose, Pa Near Northeast Philadelphia USA.
Registered: Jan 2000
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posted 02-06-2001 06:14 PM
Thank you for your replies. Randy, I am not sure which "flavor" of Simplex I have, but as you mentioned, these units all seem to thread the same as someone else has recently told me. In regards to the loop sizes, I was told by my trainer to build the top loop so that it looks level with the top of the bolt holding the one sprocket, so it sounds easy enough, but the bottom loop is the one I think I'll have the most problem trying to get the right size. I work again on Friday, so I will get another look at the projector and see what other information I can get. I, for some reason remember that this topic was discussed before so any information I can read on it will be a great help. Luckily I'll have the trainer right over my shoulder to help me out. As soon as I get the info on Friday, I'll post it. Thanks again.
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Brad Miller
Administrator
Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99
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posted 02-06-2001 07:58 PM
A few words of warning/clarification on the above tips:
Do not expect that when the "FRAME" control is level that the framing control is centered in it's path. It is possible this was never set in the first place. I have seen 10 year old theaters that in all that time the framers were never "leveled" properly. Check for yourself that the red or white engraved line on the intermittent is vertical. You can then set the FRAME control by pushing in on the knob and rotating it to the proper position, which will not move the intermittent while you are doing this. Again, do not just assume that the knobs are centered.
NEVER use the "two finger" rule. I can assure you that my two fingers are not the same size as your two fingers, which are not the same size as John Pytlak's two fingers, which are not the same size as Pat Moore's two fingers, etc, etc, etc. Whoever came up with this idea really should be shot. It is the all time STUPIDEST guideline I have ever heard in regards to the projection room. If you are being trained by someone that says that, you might as well completely ignore all advice you are given by the bonehead.
On the loop sizes, do you have a straight (flat) gate, or is it curved? That makes a world of difference in the proper upper loop size. On the lower loop I agree with Darryl's test, but want to add one very important thing to it. When setting the intermittent before threading, you should be spinning the flywheel downward and don't just stop "anywhere" in the dead part of the intermittent's travel. Stop right at the start of the dead area immediately after the intermittent sprocket has finished it's turn...and do not go any farther. This way, when you thread you can simply push upward on the lower loop to see if it slaps up against the back wall of the projector, as it will already be positioned at it's largest point. If it only touches the very top tip of the back wall, you are fine. This is the maximum size that lower loop should be threaded and is generally right on target for the typical auditorium. If you do not cue the intermittent in this fashion before you thread, you will need to be hand advancing the motor to ensure that you are checking for slapping against the back wall at it's largest point, which is a pain and wastes time. Cueing the intermittent in this fashion guarantees that the loop will already be at it's largest point to check with.
On the framing control, other than centering it properly one time, you should never ever have to touch it again. If you thread it and find the need to touch that framing control, you have threaded it wrong. Open the gate and move the film up or down to center a frame in the aperture. Never touch that framing control. Your shows will not start "perfectly" in frame if you have touched the framer during threading and you will have to do a minor adjustment on screen to your paying patrons. It is unprofessional and easily prevented.
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Randy Stankey
Film God
Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99
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posted 02-06-2001 10:38 PM
Wanna' check to see if your bottom loop is EXACTLY right?Take and thread up a piece of leader. Make sure it's good and long. Thread up the way you THINK is right. Use a magic marker and reach in through the front of the gate and make an "X" on the frame of film that's in the projection aperture. Then just turn the flywheel until exactly 20 frames of film have gone by. If you have done it right, your "X" should be now be positioned exactly even with the LED (or solar cell) in your sound head. If it's not then unthread the film and do it over until you get it right. If you know the frame offset for your digital penthouse reader you can do a similar thing by making an "X" on the film even with the scanning point in the reader and then advancing the film till the "X" is in the projection aperture. Ask your tech/engineer (or whoever your local "smart guy" is) what the offset is set to. If you have a CAT 700 or CAT 701 penthouse reader for your Dolby Digital system and you REALLY want to cover your ass six ways from next Sunday, you can get yourself a piece of "BULLET FILM". That's a special test film from Dolby that lets you set the offset to the EXACT number of frames. (Actually it's accurate to the SPROCKET HOLE!) You can use bullet film if you've got a Dolby Digital "basement reader" too, but as we all know, BASEMENT READERS SUCK!  DTS and Sony also make similar test films for their systems.
PS: I did say not to use the two finger thing, didn't I?
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