Film-Tech Forum ARCHIVE: Frame Drift?

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Posted by Dave Bird (Member # 490) on 01-30-2001, 10:09 PM:

Ran some film through "#2" tonight (boy, she sure can pile up in the soundhead in an awful hurry if you've jammed your take-up belt!!!). Noticed a little bit of "drift" on the framing adjust, which also occurred with no film. But after I shut it down, I noticed that I'd started with it cranked all the way.

Let me see if I've figured this out. Frame adjust is meant to be started in the centre, and tweaked slightly as need be?????? Threading up with it cranked all the way meant that I never could quite get it back in frame (or to stay still). Also, it's spring-loaded. Is this to tighten it up? Should it be depressed when adjusting? Thank you.

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Dave Bird

Posted by Ken Layton (Member # 133) on 01-30-2001, 10:38 PM:

What make/model is the projector in question?

Posted by Paul G. Thompson (Member # 655) on 01-30-2001, 11:18 PM:

Make and Model of projector? Sounds like a Pro-35 to me. if it is, it is a very easy fix. If it is a Brenkert, likewise it is a very easy fix. So is Century. Simplex? Ummmm-may be a little harder to fix.

Posted by Dave Bird (Member # 490) on 01-31-2001, 06:04 AM:

Sorry fellows, they're XL's (black early to mid 60's).

Posted by John Pytlak (Member # 331) on 01-31-2001, 06:12 AM:

In general, the framing adjustment should normally be run in the center of its range. When threading, always be sure to advance the projector by hand so the intermittent is in the "dwell" (sprocket not moving) position, and then position the film on the sprocket in frame. If you've done this correctly, and have inspected the print to be sure all splices are "in frame", further adjustment of the framing knob should be unnecessary. IMHO, a skilled projectionist never lets the audience see an out of frame image.

Although the framing could theoretically be set up precisely and "locked down" using the SMPTE 35-PA (RP 40) test film, in reality, slight vertical shifting of the image may occur from print-to-print, depending upon the type of printer used. So final setting of the framing usually needs to be optimized for each print by actually looking at the picture on the screen. If you do need to adjust the framing, do it discretely, so the audience is unaware of the movement. And NEVER show the framelines.

Obviously, a loose framing knob that "drifts" on its own calls for repair.

------------------
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

Posted by John Walsh (Member # 168) on 01-31-2001, 08:15 AM:

Yes, usually the framing knob should be in the center of it's travel. If it's the same as most Simplex's, the spring-loaded knob can be pushed in, then rotated to center the word "FRAME." This allows you have a reference to return it if you were out of frame. (Tip 'o the hat to Brad for that bit o' info!)

There are a few tricks to lessen the audience seeing you adjust the framing, like (if) the scene pans down, you turn the knob at the same rate. Of course, if you are exactly 2 sprockets out, it's pretty hard to hide it...

Posted by John Pytlak (Member # 331) on 01-31-2001, 08:53 AM:

John Walsh said: "Of course, if you are exactly 2 sprockets out, it's pretty hard to hide it..."

Practice the correct threading and splicing procedures until you NEVER show the audience a frameline! That's part of being a skilled projectionist.

Posted by John Walsh (Member # 168) on 01-31-2001, 10:53 AM:

Speaking of framing, does anyone know of a way to mark the framing knob on a Simplex to *exactly* show the correct position?

Where I work has adjustable top masking, which means the framing has to be adjusted when going from one format to another. Is there anything/anyway I can indicate where the knob should be for each? I have a peice of tape on there now, but it's really not accurate enough.

Posted by John Pytlak (Member # 331) on 01-31-2001, 11:59 AM:

John:

Another good reason to design theatres with constant height masking, and adjustable side masking. Common centerlines are much easier to handle.

Could you attach a long indicator pointer to the framing knob shaft to magnify the rotational position in reference to fiducial marks indicating the best framing position for each format?

Posted by Scott Norwood (Member # 30) on 01-31-2001, 12:59 PM:

Top masking is a pain. We had it at the Williamsburg Theatre (pics in the gallery here; it was an early CinemaScope conversion circa 1954), and switching from scope to flat/1.85 required a framing adjustment, while switching to Academy ratio required both a framing adjustment and an adjustment of the projector bases. This is one of the problems that results from trying to convert a theatre designed to show Academy-format films to adapt to the widescreen era.

Posted by Paul G. Thompson (Member # 655) on 01-31-2001, 02:38 PM:

With respect to the frame drift: When the frame knob is rotated, does it rotate "too" easily? Or do you have to use normal hand torque to turn it? Compare it with another machine that does not drift.

If it turns much too easily, it could be the collar or a "C" clip on the framing shaft assy became discombooberated. (made that word up myself) Or maybe a broken spring. It is basically an easy fix. If normal hand torque is needed to turn the frame knob, frame slippage might be caused by a problem with the intermittant. Roll the machine forward by hand, and see if you can feel any extra resistance when the pull-down cycle starts. It should roll nice and smooth without any noticable changes. If it feels like it is starting to bind, you better call for another movement, as what you have may be ready to cease up.
Also, without film in the machine and the film trap open, start the motor and then shut it down. If on rundown, it starts to give you the "Clunkity Clunkity Clunkity" thing several seconds before it comes to a complete stop, it would probably give cause for some very serious thinking about replacing the movement or finding out what may be causing it. These are just some things to check. Good Luck.

Posted by Paul G. Thompson (Member # 655) on 01-31-2001, 02:43 PM:

Scott, I have been yelling that for years!

Posted by John Walsh (Member # 168) on 01-31-2001, 03:24 PM:

You'd have to see a Simplex to know what I'm talking about. The knob is on a long shaft that is under (but not part of) the shutter housing. There's no easy place to put a long pointer on it without the pointer getting in the way when you grab the framer. The pointer would have to be bent around the shutter housing and out to the front to work. Now, if it was a Century, it would be easy.....

Having adjustable top masking is a pain... but you need to 'play the cards you're dealt'....

I'm not *entirely* against adjustable top masking. (As Scott noted), this theater is older (designed for 1.33) with about 800 seats. The original screen area was 32ftW. x 24ftH. Customers demand bigger screens today, and would not be too happy with a 24ftW x 13ftH flat, especially in an 800 seat house. We adjust the lamp to be pretty even with both formats. There are beams to hold up the roof on each side of the screen, which can't be removed.

Has anyone ever motorized the projector pedestal to tilt automatically? That would do it!

Posted by Dave Bird (Member # 490) on 01-31-2001, 06:27 PM:

I believe it only occurs when you start at the extreme end of it's travel (which, of course, you wouldn't do). But I can turn it WITHOUT depressing spring, so I wonder if that's a problem? When I started in the centre, I could only get it to drift if I cranked it all the way "up" to the extreme (it would migrate towards centre). (Not to worry, Shelly Long's "Outrageous Fortune" trailer is my perpetual "guinea pig", so I'm not ruining anything much!) Thanks all....

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Dave Bird

Posted by Mark Gulbrandsen (Member # 72) on 01-31-2001, 06:34 PM:

Dave,
The intermittent carrage that rotates is held in by two clamps. These are fixed metal clamps that cause uneven wear on the edge of the casting in projectors that are framed allot. They are a pain to adjust properly when the wear becomes uneven. One of the many fixes that Strong did was to get rid of the metal clamps and design a new spring type clamp to solve this wear problem. The spring clamp puts even tension on the carrage no matter what the wear is. This is also a good indication that the projector has been framed allot causing this wear. The spring clamps are cheap, around 2 bucks apiece and replacing them should eliminate any drift.
Mark @ GTS

Posted by Paul G. Thompson (Member # 655) on 01-31-2001, 06:42 PM:

David, what you said:

>Let me see if I've figured this out. Frame adjust is meant to be started in the centre, and tweaked slightly as need be?????? Threading up with it cranked all the way meant that I never could quite get it back in frame (or to stay still). Also, it's spring-loaded. Is this to tighten it up? Should it be depressed when adjusting? Thank you.<

Something is fishy here. I never heard of having to depress a spring while adjusting the frame knob. It sounds to me like you have a "C" clip that flew off the shaft that has the framing knobs. Look at where the framing knob shaft goes through the projector casting and see if all the parts are there.

Posted by Paul G. Thompson (Member # 655) on 01-31-2001, 06:51 PM:

Mark, the Fricton Spring P-1755 should provide enough tension on the P-1752 Framing Shaft Friction Disk Washer to keep the intermittent from walking the carriage. If he finds all his parts are on the shaft where they belong and the spring is not broken or collapsed (literally), then the two little P-1705 clips you speak of are badly sprung, worn, or broken. But Dave has not indicated if the machine rolls forward very smoothly without binding yet. So I don't know what kind of shape his movement is in. I am presently under the impression that it creaps no matter where the frame knob is positioned.

Posted by Francis Casey (Member # 514) on 01-31-2001, 07:26 PM:

To John Walsh
Re marking the framer knob--the newer Simplex Millenium projectors use a T-HANDLE as the framer knob , this would allow you to more accurately judge and or mark your flat and scope framer position . I don't know the part number , but you can order them from Strong or your cinema equipment dealer . They are a direct replacement for your old ROUND black framer knob .
Francis

Posted by Paul G. Thompson (Member # 655) on 01-31-2001, 07:52 PM:

Part Number is P-10159, according to the manual.

Posted by Dave Bird (Member # 490) on 01-31-2001, 07:59 PM:

Paul, I really need to run this machine more, but I believe it only creeps back toward centre from extreme clockwise framing (on the film side). The machine seems very quiet otherwise, it does need replacement of shutter blade (cracked "hub"). No, I don't have to "depress" spring to turn framing, I just didn't know what the spring was for.

Should the intermittent be opened up each day and oiled a bit before starting? Also, will cold or even freezing temps adversely affect start-up? I think I may have started it a little prior to the garage warming-up. Another thought is that I may have threaded improperly. I'll give it another go tonight.......

Roughly how far (in frames) will these things move your picture? One thing I need to do is get the framing lamps hooked up, right now I can't really see where I'm framing.....

"Expert" Dave!

Posted by Paul G. Thompson (Member # 655) on 01-31-2001, 08:12 PM:

Dave, then I would suspect your problem is the little clips Mark was talking about.

No, it is not necessary to open the machine up every day to oil the movement, and Yes, cold or feezeing temperatures will effect the start-up. If at all possible, let the room come up to a fairly comfortable temperature level if all possible. If you can see your breath, it is just too darn cold! I have run some drive-in's in the winter time where it was so cold, the motors could not bring the machines up to full speed. It is obvoiously hard on motors, and projectors, too.

A nifty thing I was taught in MPO school is to use a flashlight and articulate it in such a manner whereas when you look down the barrell, you can see if you are in frame or not. There are other means at your disposal to determine if you are framed correctly.

Posted by Brad Miller (Member # 2) on 01-31-2001, 08:20 PM:

Dave, on the intermittent should be a tiny marker line. It should be pointing straight up to center the travel and ensure it gets oil from the bath.

John W, I've never heard of a motorized base tilt, but I have seen operators place a piece of tape on the wheel and they know how many turns clockwise to reach this lens setting and counterclockwise to reach that lens setting. Works well, but is just something else to have to deal with when changing formats.

Posted by Paul G. Thompson (Member # 655) on 01-31-2001, 08:32 PM:

Brad, that is a very good point. I have an XL intermittant sitting next to my keyboard, and to be quite frank about it, and all the years I run XL's, it never occurred to me the little red line could be used as a reference as you described. Thanks for the tip.

Posted by Dave Bird (Member # 490) on 01-31-2001, 09:16 PM:

Given a nice warm room and a snugly fit "shutter-blade guard", she was just fine tonight without film. Centred framing, good with film, with a slight bit of drift at the extremes. Yes Brad, I had frigged around with it and sort of thought the sweet spot was "red-line up" rather than the word "FRAME" level as the old manual suggests (suppose that's easy to fix). The clamp that holds the spring on the framing shaft is a PA-1570. An allan-key is here and on the "non-spring" side. Is that meant to be adjusted for more "retention". Thanks so much guys, this is fun.....I still think my framing is lousy and possibly too tight. I can cheat in reverse, with no lamps, I can thread right through the aperture plate. But I ought to get 6000' reels, I wouldn't trust myself to be ready for 20min. changeovers at this point!

Posted by Mark Gulbrandsen (Member # 72) on 01-31-2001, 09:32 PM:

Dave, While that can be adjusted for more or less tension that is not the correct thing to do. There is obviously another problem going on here. The shaft should be adjusted for normal framing tension. I have used a partial projector with no framing shaft at all to run in overhauled movements for years and it never crept at all. It does have those nifty spring clamps in it though.
Mark @ GTS

Posted by Steve Guttag (Member # 268) on 01-31-2001, 09:52 PM:

Even putting just one of the spring style clips will stop a walking intermittent. Getting to the lower clip can be a pain if time is tight.

Another cause of wondering framing, though it doesn't sound like it in this case, is the shutter compensator...if it is vibrating..the compsator can "tap" on the intermittent case and cause it to rotate. A really bad compensator can walk the framing around in about 15 seconds.

Steve

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"Old projectionists never die, they just changeover!"

Posted by Paul G. Thompson (Member # 655) on 01-31-2001, 10:34 PM:

Steve, that is why I was asking about the "Clunkity" run-down. The compensator is driven off the vertical shaft via G-1803, and would not cause frame drift. Just a lot of racket and pulsating travel ghost. I have never seen that happen, but then again, it is not good to "never say never". However, I saw one compensator running where the casting was actually broken with the shaft thrusting in and out, but it never walked the intermittent.

Posted by Brad Miller (Member # 2) on 02-01-2001, 12:04 AM:

Dave, A little tip...center the framing via the line on the intermittent and then push inward on the round "FRAME" knob. When it is pushed in fairly hard, it is designed to be able to be repositioned so the word FRAME is level. That way at a glance, you know if you are centered.

Posted by John Hegel (Member # 628) on 02-01-2001, 01:33 AM:

I have a question, what if my XL is making the "Clunkity" run-down, and start up. The noise has just started getting really bad, and I was wondering if there is something I can do to prevent it from getting any worse.

Thanks for your help,
John

Posted by Steve Guttag (Member # 268) on 02-01-2001, 07:40 AM:

Paul,

Yes the shutter compensator is driven off the G-1803 but the shutter compensator has it's framing rod and roller (P-1479 and P-1480 respectively) riding on the intermittent framing cam (P-1708). Depeding on the strengh of the P-1705 clips and the vibration transmitted through the framing rod (from a vibrating compensator), the framing rod will actually push the cam around.

Steve

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"Old projectionists never die, they just changeover!"

Posted by Dave Bird (Member # 490) on 02-01-2001, 09:17 AM:

What I should do is print this thread off and go looking for all this stuff. The only thing with a spring under it is the PA-1570. Other than that, just a round disc on the other (gear) side. I take it that you can put a spring on this side also. 30 years + at the drive-in could have worn the existing ones down, however it seems like it's okay if I start in the middle. Perhaps I'll install them anyway, does anyone have a part number, or are they shown on the old parts manual?

Posted by Paul G. Thompson (Member # 655) on 02-01-2001, 11:35 AM:

Steve, the way you described it, I can see how it could happen. Thanks for the tip. Much appreciated.

- Paul

Posted by Paul G. Thompson (Member # 655) on 02-01-2001, 11:48 AM:

John, if the intermittent is running smooth and free with no binding on pull-down, you might have a compensator or a gear train problem. Try different settings of the frame knob. It might help you isolate what is going wrong. There may also be a gear or bearing going south on you. I would also try the run-down thing without the intermittent in the projector. But first, check to make sure the flywheel on the intermittent is tight. It almost sounds like a loose flywheel.