Film-Tech Forum ARCHIVE: Simplex PR 1050 Gate/Trap Tension

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Posted by Michael Elam (Member # 788) on 08-18-2005, 02:55 PM:

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? [Eek!]

Posted by Dan Lyons (Member # 1454) on 08-18-2005, 03:06 PM:

Run your loop of RP-40 and slowly increase your tension until image is steady. [thumbsup]

Posted by John Pytlak (Member # 331) on 08-18-2005, 03:12 PM:

quote: Dan Lyons
Run your loop of RP-40 and slowly increase your tension until image is steady.

That's fine, but I really suggest optimizing the tension for each film you run, as things like process machine drying conditions and the age of the print can affect the optimum setting. Yes, slowly increase tension until steadiness is good, then go no higher. If you have to use very high tension, something else may be wrong.

Posted by Dan Lyons (Member # 1454) on 08-18-2005, 03:49 PM:

quote: John Pytlak
That's fine, but I really suggest optimizing the tension for each film you run

You've got to be joking. [Confused]

That would be reasonable if someone was going to be running an old brittle 4-track mag print (anyone who would ask about this wouldn't or shouldn't be running that type of thing to begin with), but I'm pretty sure the question here was about setting the tension for poly prints at your run of the mill multiplex.

Posted by John Pytlak (Member # 331) on 08-18-2005, 04:02 PM:

It's a "suggestion" for getting optimal quality. You "tweek" focus when you start each feature, don't you? How long would it take to "tweek" the tension too?

Posted by Monte L Fullmer (Member # 2797) on 08-18-2005, 04:17 PM:

is your trap and gate assembly, the flat gate style, or the curved gate variety?

If the curved gate, you'll have to watch out for excessive band wear, especially at the top of the bands where the upper loop can make contact when the film enters the trap.

I always maintain the tension knob at the "1" position for curved gates. Flat gates can be variable if needed.

Now, if you're having trouble with picture steadiness and having to send the tension up to the max, the trap and gate assembly has an adjustment for closure. And that adjustment is the gate stop allen screw located on the trap side assembly below and right of the aperture plate .

This screw is what stops the gate at a precise point.

Adjust this screw to where the gate can close a bit tighter with the setting knob at minumum to where the picture is steady and the film is actually running smooth through the assembly.

This is a step method of adjustment-by taking off the gate, adjust the screw a bit, rethread to see if steadiness is there, if not, repeat the cycle until the goal is achieved.

-Monte

Posted by Gordon McLeod (Member # 33) on 08-18-2005, 04:38 PM:

quote "Run your loop of RP-40" there is no such thing as a loop of RP40 [Smile]

The test film in question is 35PA

Also it is on BW stock typically and a different sprocket pitch so again it isn't the best choice
Also there is differences between print runs and labs for the amount of moisture in the print and also the amount of lubrication so it needs to be adjusted on a per print basis
The minimum tension required to maintain focus and steadiness is all that is wanted

Posted by Steve Guttag (Member # 268) on 08-18-2005, 04:48 PM:

Nope, John was not kidding...tension should be checked on a print by print basis with the lowest tension needed to do the job. On a Simplex and Century with just 5 detented positions this might seam crude but on other brands, the tension is quite variable and in the case of a Norelco AA2, can be easily mal adjusted when the gate is opened.

As to setting gate depth as a form of tension adjustment...that is just plain silly. Generally, without binding the film, you want the gate as close to the aperture but allowing for the film to swell such that it never can blister into the aperture plate. With higher wattage lamps, about 1/8" is a good starting point, with smaller lamps a closer gap can often be had but make sure you don't bind the film as it exits or enters the gate. The closer you get the gate to the aperture (again with out binding or blistering the film) the less of a "fringe" area you will have and less bleed on the masking.

Tension bands don't come into play on this...depending on the projector, there are other tricks of the trade to get them optimised and for Simplex and Century, ideally set to "1" for most films.

Posted by Gordon Bachlund (Member # 124) on 08-18-2005, 05:38 PM:

RP 40 is the specification for 35-mm Projector Alignment and Screen Image Quality Test Film. [Smile]

Posted by John Hawkinson (Member # 1135) on 08-18-2005, 06:23 PM:

Yes, but RP40 can refer to both 35PA (black-and-white) and 35IQ (on color stock).

--jhawk

Posted by Gordon McLeod (Member # 33) on 08-18-2005, 06:28 PM:

actually it isn't can but does refer to the use of either test film the point being there is no RP40 test film

Posted by Mark Gulbrandsen (Member # 72) on 08-18-2005, 08:13 PM:

quote: Dan Lyons
You've got to be joking.

Well the Simplex(Pile-O-Pot Metal) trap/gate is quite crude but it can work well if one pays attention to what you are running through it. Not only does the trap band tension adjustment affect steadiness it also can affect how well the image focuses on the screen. Merely running a tst loop won't do much good. You have to pay attention to the film you are running through at any given time and get used to how your particuluar machine behaves and then set it to achieve best steadiness and flatness of focus. I find that normally the tension knob will lie somewhere between the first and third click stop.

Mark

Posted by Dan Lyons (Member # 1454) on 08-18-2005, 10:28 PM:

So we should all "ride" the tension knob and also adjust for each trailer we run. [evil]

quote: Gordon McLeod

Also it is on BW stock typically and a different sprocket pitch so again it isn't the best choice

I've run two features printed on stock with that type of sprocket pitch in the past year, both ran just fine and looked good on screen.

Posted by Monte L Fullmer (Member # 2797) on 08-19-2005, 02:03 AM:

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

..I've done that a few times...sometimes with old acetate stock, and "green" prints.

There is no such thing as perfect film just as there is no such thing as a perfect machine, for each roll of stock (or even emulsion) could be a few microns difference in thickness, but generally most machines, if adjusted correctly can "forgive" this difference of thickness per each roll.

-Monte

Posted by Scott Norwood (Member # 30) on 08-19-2005, 06:16 AM:

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?

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

Posted by Mark Gulbrandsen (Member # 72) on 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

Posted by John Pytlak (Member # 331) on 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.

Posted by Darryl Spicer (Member # 711) on 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.

Posted by Gordon McLeod (Member # 33) on 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]

Posted by Brad Miller (Member # 2) on 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!

Posted by Mark Gulbrandsen (Member # 72) on 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

Posted by Gordon McLeod (Member # 33) on 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

Posted by Brad Miller (Member # 2) on 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]

Posted by Gordon McLeod (Member # 33) on 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

Posted by Don Furr (Member # 1469) on 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

Posted by John Hawkinson (Member # 1135) on 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!

--jhawk

Posted by Gordon McLeod (Member # 33) on 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

Posted by Phil Hill (Member # 371) on 08-20-2005, 07:30 PM:

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

Posted by Louis Bornwasser (Member # 3063) on 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

Posted by Mark Gulbrandsen (Member # 72) on 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

Posted by Brad Miller (Member # 2) on 08-20-2005, 11:28 PM:

quote: Mark Gulbrandsen
Thats why I prefer DTS! The track is in a no contact area...at least if the machinery is set up correctly.

I prefer real projectionists who know how to take care of their prints. [Razz]

Posted by Monte L Fullmer (Member # 2797) on 08-21-2005, 02:04 AM:

quote: John Hawkinson
We use abbreviations and shorthand like that in-and-out of our daily lives.

..and I get chewed out for using INT for intermittent (lol)...

quote: Brad Miller
real projectionists who know how to take care of their prints

Unfortunately, in this day and age, we have to make things simple for these circuits who uses those "B"-ushers running their complexes, instead of paying to have "real" projectionists to run things correctly - thus why DTS is the easiest digital to use (as long as they remember to switch the discs around when moving prints around). I say this because I'm SURROUNDED by these morons at work and in this area here.

Maybe, it's time for us "real" projectionists either to retire and forget all about this, or find a different career and watch the movie-going world do it's thing as it wants to.

-Monte

Posted by Brad Miller (Member # 2) on 08-21-2005, 02:15 AM:

Monte, think about what you just said. Anyone who is a lousy projectionist surely won't be bothered with moving those dts discs around. [Wink]

Posted by Monte L Fullmer (Member # 2797) on 08-21-2005, 02:24 AM:

lol...true. And I've seen piles of discs floating around in many booths due to the extreme laziness (or lack of knowledge-which is usually the latter) of booth handling.

..if they would only know....

So..in comes SR-D as the 2nd best for Digital. A little wear between the sprocketholes that can still keep a decent error rate, but no discs to mess with.

Now, that is what's called "simple."

-monte

Posted by Steve Guttag (Member # 268) on 08-21-2005, 10:15 AM:

quote: Monte L Fullmer
and I get chewed out for using INT for intermittent

Who in the world would do that? [Wink]

Posted by Monte L Fullmer (Member # 2797) on 08-21-2005, 11:40 AM:

lol...I'll give you three guesses and the first two don't count.. [Big Grin]

Posted by John Hawkinson (Member # 1135) on 08-21-2005, 12:09 PM:

Wellllll, Monte.

"Which ones are acceptable versus which are not are driven by accepted practice and convention."

and then:

"and I get chewed out for using INT for intermittent (lol)"

That's because most people don't understand your TLAs (Three Letter Abbreviations); they aren't commonplace, and are often inscrutable, especially for new Film-Tech participants who are trying to learn.

I think using INT, CHR, etc., is a bad idea, and I do wish you would spell out the word; it's not as if they are really long multi-word polysyllabic behemoths. It makes FT (Film-Tech!) a lot friendlier to use the spelled-out words.

--jhawk

p.s.: Gordon, right you are! How could I have forgotten the new RP 40 edition? Shocking! [uhoh]

Posted by Steve Guttag (Member # 268) on 08-21-2005, 12:45 PM:

In truth, I also find the 3-letter abbreviations annoying or the other oddity...MIL2000...it is a PR-2000 or Millenium...even in the 3-letter world it would just be MIL (too close to Mil-spec, I guess).

Now there are other common place abbreviations that have been used since ASCII or text messaging has been around...things like LOL (laughing out Loud), IIRC (If I Recall Correctly) that I will conceed have been in use by non industry people since before the WWW (World Wide Web). They tend to be expressions or sayings rather than a contraction of a proper name.

Often, just a model number is sufficient...does the AW3 conjur up anything in this forum other than Christie platter by that name? If it did share a name with a common piece, then I can see adding the manufacturer to the name.

In the case of 2000...there can be MANY...Just from Simplex there is the PR2000 and the TU2000. However, the PR and TU pretty much narrows down the field.

Back on the first level of off topic...the RP40...it is not proper to call the film by that name. The Document is RP40 without a date...the date denotes the latest revision...if one were to quote a statement off the document, as John P just might...then it is proper to denote the revision since anything that is revised may have changed since the last revision and what was correct in yesteryear may no longer be the case. The test film described in RP40 is called 35-PA...you can't order RP40 from SMPTE (without just getting a paper describing the test film) but your can order 35-PA or 35-IQ.

The problem wiht the target was that it contained (and It probably still does, I can't recall) the "RP-40" name on the target...making the mistaken name very easy to understand. Since the same target is used for IQ as PA, it would not be possible to have the designation change. It also would drive cost way up to change targets and then recheck accuracy (waste film and time).

In any event, 35PA with BH-1866 is a poor target to use to set gate tension, or depth in motion picture projectors. It is best used for measuring resolution and projected image (including shutter ghost). Will gate depth affect resolution across the image, quite possibly but it still isn't the best/only method.

Posted by Mark Gulbrandsen (Member # 72) on 08-21-2005, 03:08 PM:

quote: John Hawkinson
I think using INT, CHR, etc., is a bad idea

Whats the matter... can't you girley men keep up with Monte? I certainly don't have problems with the abbreviations.... it saves bandwidth on this site and in fact when you meet and work with Monte he also talks like that.... so you'd better be on your toes!! Monte, perhaps you should put together a list of your abbreviations so these girley men can look them up.....

Mark

Posted by Phil Hill (Member # 371) on 08-21-2005, 03:44 PM:

UNCLR ABRV BLW!

Posted by Monte L Fullmer (Member # 2797) on 08-22-2005, 03:49 AM:

I could be mean and and start with..Mil2K,TU2K,OSR(am),Kino15's, CineV18's...et.al. (LOL)

Thx Mk for your supp't. (hey, it's just tekkie talk in which I picked this years ago-a language that we've just learn to understand from one another..)

True JHawk, I can see where you're coming from - having to speak on a level for the "newbies" that come into this forum that want to learn what we have to offer.....

-Monte