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Topic: Simplex PR 1050 Gate/Trap Tension

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 08-19-2005 08:10 AM

Scott,
There are also spring steel connecting plates that connect the H shaped gate runner to the plate that mounts it to the tube. These spring steel connecting plates also provide at least some film tension as well with the knirled nuts over the springs backed off. It slao depends on exactly which C gate assy that you have. The one I described above is the most common though....

Mark

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 08-19-2005 10:00 AM

quote: Scott Norwood
I've run a number of Century "C" projectors that give a perfectly steady image at the minimum tension setting possible (without removing the nuts completely). Is this a sign that something is wrong with the gate/trap assemblies?

No, it's likely fine. It really should not take much tension to achieve a steady image. You are just trying to have the tension in the gate hold back against the inertia of the short length of film in the gate. Putting too much lubricant on the film (e.g., overapplication of FilmGuard) may require increased gate tension because the film has such low friction.

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Darryl Spicer
Film God

Posts: 3250
From: Lexington, KY, USA
Registered: Dec 2000

posted 08-19-2005 10:12 AM

quote: Michael Elam
On a Simplex PR 1050, what is the best way to determine how tension is to be on the Gate/Film Trap? Just enough to keep the
film still?

When I worked with those machines, what I would do when I changed out the bands is this. I would verify the stop position of the gate by making sure that the intermittent shoe was just in far enough to allow contact and clearance of splices and then adjust the band tension to one, note the bandtension would already be on one before I adjusted the stop position. If the picture was still unsteady to a large degree I would adjust the stop position of the gate in slightly to see if that cleared up the jump. If it did then I would leave the tension alone. If not then I would adjust the tension to the next number. Usually that steadied things up.

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 08-19-2005 11:50 AM

quote "So we should all "ride" the tension knob and also adjust for each trailer we run"

Well I can well remember when theatres still employed "reel Projectionists" we even had cue sheets for volume level changes [Smile]

And yes I would still expect a projectionist to correct framing, tension, and focus as required to ensure the best presentation to the paying public after all that is what they are being paid for [Cool]

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 08-20-2005 04:09 PM

quote: John Pytlak
You "tweek" focus when you start each feature, don't you? How long would it take to "tweek" the tension too?

I don't know about you, but I consider it bad form to permit the image to jump on the screen every time a feature is started to verify you are at the lowest setting possible. Also, trying to find the absolute lowest possible tension setting is a pretty foolish thing to do, as often different reels of the feature will be a little more slick than others, and then there is the potential for film cleaning, projector oil dripping on the film, etc that could also cause variation in the slickness of the film, not to mention dirt and emulsion deposits in the gate from people who don't clean their films, blah, blah, blah. Add all of these points together and put it in a multiplex environment where there is one projectionist (if any) on duty and it's just an absurd thing to even imagine. Come on guys, wake up. A projector should be able to have one setting that works for all polyester film in the building, and with the exception of that first pass after a fresh coating of FilmGuard, the tension should be able to be left alone the entire week for a typical multiplex. If I can run prints for 6+ months at a time without EVER toucing a tension adjustment on any projector in a multiplex booth and STILL have the SRD error rating track 0s and 1s, so can you.

quote: Gordon McLeod
there is no such thing as a loop of RP40

Yes there is Gordon. Just because YOU are out of it doesn't mean someone else doesn't still have a stockpile of it. [Wink]

quote: Scott Norwood
On the other hand, Century JJs running mag 70mm _definitely_ require tension adjustments for every film and, sometimes, every reel of every film.

Scott, that JJ you ran 70mm on clearly has issues!

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 08-20-2005 05:01 PM

quote: Brad Miller
If I can run prints for 6+ months at a time without EVER toucing a tension adjustment on any projector in a multiplex booth and STILL have the SRD error rating track 0s and 1s, so can you.

Brad,
It just dawned on me that your DD decoders can't count any higher than 1 and that why you only see a max. of 1 on error rating. The DD decoders around here are simply just smarter and can count all the way to 7 [Wink]

. But since when does adjusting the gate tension have anything to do with lowering error rate? I thought those were two completely different units..... Aren't you supposed to also adjust the the other tension knob over on the penthouse reader seperately [Eek!]

?

Mark

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 08-20-2005 05:03 PM

quote Brad "Yes there is Gordon. Just because YOU are out of it doesn't mean someone else doesn't still have a stockpile of it. [Wink] "

Sorry but there has NEVER been a test film called RP40 produced by SMPTE many people are under the impression that 35PA is that but RP40 is a text document on how to use the Projector Alignment film

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 08-20-2005 05:48 PM

Mark, higher tension causes more wear to the SRD and SDDS tracks. As such, unnecessarily high tension will scratch them right off, inparticularly if the projectionists are not lubricating and cleaning the film! That's what I was referring to.

Gordon, haha ok you got me. I've heard the 35PA called RP40 by virtually everyone for 20 years. Some things just stick, but still we all knew what he was talking about. [Wink]

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 08-20-2005 05:51 PM

Brad there is a first time for everything [Smile]

One thing to watch is excessive gate tension will wear down the delrin skates in kinoton equipment very fast

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Don Furr
Jedi Master Film Handler

Posts: 509
From: Sun City, Ca USA
Registered: Nov 2002

posted 08-20-2005 06:35 PM

What da hell??? no RP-40??? I've been wrong all these years?? You mean we don't get French benefits??? [Big Grin]

Don

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John Hawkinson
Film God

Posts: 2273
From: Cambridge, MA, USA
Registered: Feb 2002

posted 08-20-2005 07:05 PM

Come on, Gordon! When we say ``RP40'' in the context of a test film, it's a shorthand for saying ``test film compliant with the latest published edition of SMPTE Recommended Practice 40.''

We use abbreviations and shorthand like that in-and-out of our daily lives. Which ones are acceptable versus which are not are driven by accepted practice and convention. Sometimes we make a technical decision that a certain shorthand is wrong, because it promotes confusion or blurs a distinction that may be important.

I don't think we have such a case here--do you? The term ``RP40'' is consistently used within the industry to refer to 35-PA or 35-IQ, generally in cases where it's not too important which you use.

Would you like us to take you to task for saying ``RP40'' and ``35PA'' instead of ``RP 40-1995'' and ``35-PA''?

There is no such thing as RP40! It is RP 40-1995! [Big Grin]

--jhawk

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 08-20-2005 07:28 PM

quote "There is no such thing as RP40! It is RP 40-1995! [Big Grin]

--jhawk"

Actually it is RP40 2003

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Phil Hill
I love my cootie bug

Posts: 7595
From: Hollywood, CA USA
Registered: Mar 2000

posted 08-20-2005 07:30 PM

Brad, Gordon, and John, yous are all sooo anal-rententive you make me sick!

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Louis Bornwasser
Film God

Posts: 4441
From: prospect ky usa
Registered: Mar 2005

posted 08-20-2005 07:57 PM

Curved gate Century projectors that run 35mm film; if set up so the film path has no issues should always run at minimum tension. When I see tension "up" I look for consequential damage to the intermittent pin. At that point, you MUST run high tension to stop the bounce caused by the worn intermittent. This then causes even more wear.

Remember XL's and Centurys guide the film between the sprocket and the lateral guide rollers for lateral guidance. The intermittent along with slight gate tension steadies the vertical.

High tension is so evil that we are considering removing the knob since there are so few knowledgeable people left.

Louis

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 08-20-2005 09:15 PM

Brad,

I was just kidding you!!! I am well aware of the damage to SRD tracks from excess tension and in particuluar Sony tracks. Thats why I prefer DTS! The track is in a no contact area...at least if the machinery is set up correctly.

quote: Louis Bornwasser
Curved gate Century projectors that run 35mm film; if set up so the film path has no issues should always run at minimum tension.

Again, I have to disagree Louis because that has not been my expereince with Centurys when used in very critical applications. I've used Centurys on close to 50 dailies jobs over the years and a very slight tension adjustment was always required for obtaining the best flat focus possible. Never made much dofference in the steadiness department unless too much tension was used, but then I'm with you in that excess tension causes to much cam pin wear, especially the crap metal cam pins they make today. Older cam pins would last and last while the present stuff just doesn't have the wear peoperties, nor does it measure nearly as hard on the Rockwell tester..... IN fact you'd be shocked to see the hardness differences between a present day LaVezzi star and cam product and an original Simplex made Star and Cam.... And then there are the metals used in the Phillips machines some of which is so hard it doesn't show any real wear after 50 plus years of use!!

Mark

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