Film-Tech Forum ARCHIVE: Simplex Tension Band adjustment

This is topic Simplex Tension Band adjustment in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=009155

Posted by Nicholas Stevens (Member # 4692) on 03-01-2008, 04:02 PM:

I have been searching the forum's and have not found a post on the proper way to set the tension on the film for a simplex projector. Can someone either point me to a post or explain the proper way to set the tension? Thanks in advance

Posted by Sean McKinnon (Member # 612) on 03-01-2008, 05:52 PM:

You want the least amount of tension possible to achieve a steady image.

Posted by Ken Lackner (Member # 1002) on 03-01-2008, 07:41 PM:

Sean is absolutely correct. As far as how to perform the adjustment, you can find the instructions in the manual, which can be found in the manuals section of this site if you do not have one. Basically, on the outboard side of the film trap, you will see a knurled knob with 5 numbers on it. Each of these numbers represents an increasing amount of tension, with 1 being the least tension and 5 being the most. Start with the tension all the way down, and only increase if you need to in order to obtain a steady picture. If your picture is steady, don't go any tighter than necessary.

I beleive that tension knob is common to all models of Simplex. At least all that I am familiar with.

Posted by Monte L Fullmer (Member # 2797) on 03-01-2008, 11:42 PM:

Only sight variation in tension is when using either Acetate or Polyster prints since "poly" film is slightly thinner than the acetate based prints.

And even such, "poly" film does have it's variances in thickness where adjustments are still necessary - but the norm still holds true: less tension the better.

Flat gate XL's had their tension knob on the gate itself since it adjusted the pressure of the the gate rails into the trap rails, whereas the curved gate units had the tension knob on top of the trap being behind the upper part of the bands and this either made the bands more slack or more tighter.

Posted by Mark Gulbrandsen (Member # 72) on 03-02-2008, 08:37 AM:

quote: Sean McKinnon
You want the least amount of tension possible to achieve a steady image.

Dudes...
I find that line absolutely hilarious [Big Grin]

! With the amount of unsteadiness we typically see in the crapo release prints of today I am finding more and more Simplex's, Century's, Christies, Norelco's, etc., whose gate tension is turned all the way up in an effort to get something stabilized on the screen. Of course these "booth mongers"... some of which are adults... can't blame it just on the kids... think they're doing their job correctly in doing so. We tell em not to turn it past 2:00 on the dial NO MATTER WHAT but by the next visit there's someone else running the booth as the last "Monger" is now the manager over at McDonalds! We rebuild alot of intermittents because of this... Doesn't seem to affect the Ultramittents though for what ever reason, perhaps more attributable to the synthetic oil in them than the actual internal parts which are identical in size to Simplex X-L. Thank God Digital Cinema is just round the corner....

At any rate you may want to revise that "standard booth line" to say... "If you have to turn it past 3 on the dial its probably not going to get any steadier so leave it at 2 to prevent excessive mechanism wear."

Mark

Posted by Sean McKinnon (Member # 612) on 03-02-2008, 09:52 AM:

Maybe I should have said "You should use the minimum amount of tension needed to stop unwanted motion of the film in the gate" [Smile]

How much should we be willing to alter our practices due to lab errors? What if release prints start to come out all with the same misprinted SR*D tracks what becomes correct? To calibrate the readers to pick up the misprinted tracks or to achieve dolby spec. ? All in all I think the labs need to get thier acts together.

Posted by Mark Gulbrandsen (Member # 72) on 03-02-2008, 10:30 AM:

quote: Sean McKinnon
Maybe I should have said "You should use the minimum amount of tension needed to stop unwanted motion of the film in the gate"

What you said makes perfect sense to those with an IQ above 63 but remember the projectionists/managers out here typically are under IQ 63.

So this is what I teach them....

You can rarely stop that unwanted motion any longer even if there were a gate pressure setting of 25 [Eek!]

. The 1:00 to 2:00 position "should give optimum results" (assuming the projector is set up properly). Any more than that is excessive and will put unwanted wear and stress on the mechanism and they will be taking the repair charges out of your paycheck.

I assume the latter threat is why they all seem to flee over to McDonalds.

Mark

Posted by Ken Lackner (Member # 1002) on 03-02-2008, 11:05 AM:

Mark, I thought that excessive tension will only wear the bands faster (and put unnecessary stress on the film, of course). How does it affect the intermittent?

Posted by Sean McKinnon (Member # 612) on 03-02-2008, 11:28 AM:

I see what you mean and completely agree with you Mark, I just like to play devils advocate sometimes [Smile]

Excessive tension will cause more drag on the film causing the starwheel and cam to have to work harder to pull down the film. The more stress when the cam comes into contact with the starwheel will cause them to wear that much faster, and develop flat spots. The more the mechanism has to work to pull the film down the more stress on the drive train also causing fiber gears to wear etc...

Posted by Mark Gulbrandsen (Member # 72) on 03-02-2008, 12:22 PM:

Three pieces suffer the most from excessive gate tension in this order:

1.Pin on the cam develops a flat spot where it strikes the slot during pull down. This development of a flat spot is normal wear over many years but is much accelerated with higher gate tension. Synthetic oil really helps in this department because it holds up much much better under the high pressures involved when the pin strikes the side of the slot.

2 Slot in the Star wheel wears faster from the extra pressure being exerted on it by the cam pin. A seriously worn slot will actually look wavey... you can fel it if you run your finger nail along the edges of the slot...

3.Face of the teeth on the intermittent sprocket become undercut faster.

4.Gate Bands will wear faster in certain spots but generally not all that much. What you get though is a stretching of the gate bands and a resultant lower tension once they become stretched. This is especially true of Apogee, Christie, and DP-70 gate bands... those machines whose bands are quite long.

Mark

Posted by Tim Reed (Member # 137) on 03-02-2008, 12:27 PM:

quote: Mark Gulbrandsen
We tell em not to turn it past 2:00 on the dial NO MATTER WHAT

The numbers are irrelevant. Tension depends on how deep the gate closure is set.

Posted by Nicholas Stevens (Member # 4692) on 03-02-2008, 12:53 PM:

Well I understand that the tension knob should be set at the lowest number possible but my real issue is that the gate's (swing open style) are not all set correctly so the tension knob on some of the projectors are all the way up and some are not. Should I adjust the gate's to be tighter or looser depending on the setting of the tension knob to get the knob's to be on the lowest settings without the film jumping all over the place?

Posted by Ron Funderburg (Member # 4561) on 03-02-2008, 02:37 PM:

What Mark says makes a lot of sense as well there is a lot of printed side to side movement in the prints we receive now and some up and down bob as well. No amount of adjustment can right what the lab hath done wrong. There is also a matter of some of the camera's used in filming are in need of being maintained now and the lab can't correct film that is traveling side to side and bobbing up and down when it is being filmed.

It is rather upsetting to use pattern film to ensure that the film is traveling right and the tension is set well only to run a movie that has bob and weave that you can do nothing about!

As to setting the proper tension I would set the settings at the lowest number and adjust the large coil spring (using a test film loop such as Schneider Test Film CLT 2000). Adjust the coils until the jump and weave stops but use some kind of test film so you know it is printed stable!

Posted by Mark Gulbrandsen (Member # 72) on 03-02-2008, 07:43 PM:

quote: Tim Reed
The numbers are irrelevant. Tension depends on how deep the gate closure is set.

Well ah Tim... there are standards for that setting on most American built projectors. If there are not then you go by ounces of tension while using a guage to determine the normal running pressure... quite elementary really!

Mark

Posted by Mark Gulbrandsen (Member # 72) on 03-02-2008, 07:44 PM:

quote: Tim Reed
The numbers are irrelevant. Tension depends on how deep the gate closure is set.

Well ah Tim... fortunately there are standard depth settings for most American built projectors so those numbers can actually serve as a refrence if you want them to. Some projectors gates click shut and have no adjustment for depth. If there are not specs as on some European machines then you go by ounces of tension using a scale guage(looks like one of them thare Fish weighn scales cept lots more accurate!) to determine the normal running pressure... 10 to 12 ounces of back tension is what is generally consdered Mid Scale er setting 3 on an X-L on that thare tension knobby. Quite elementary really!

Mark

Posted by Tim Reed (Member # 137) on 03-02-2008, 09:18 PM:

It's okay, Mark, no one expects you to know everything. The numbers don't reference anything, they're just tics. Other projectors are beside the point; he's asking about a Simplex.

Posted by Louis Bornwasser (Member # 3063) on 03-03-2008, 07:00 PM:

Hey! Don't fix that problem....I repair a lot of intermittents!

Seriously, on our overhaul machines, we set up the machine to track correctly at minimum tension. If we cannot start to attract proper "labor" we are seriously considering removing the "taper" on the shaft behind the knob. That way, they can set it anywhere they want and not destroy an otherwise wonderful machine. Louis

Posted by Mark Gulbrandsen (Member # 72) on 03-03-2008, 09:37 PM:

quote: Tim Reed
The numbers don't reference anything, they're just tics. Other projectors are beside the point; he's asking about a Simplex.

quote: Louis Bornwasser
Seriously, on our overhaul machines, we set up the machine to track correctly at minimum tension. If we cannot start to attract proper "labor" we are seriously considering removing the "taper" on the shaft behind the knob. That way, they can set it anywhere they want and not destroy an otherwise wonderful machine. Louis

Louis.... I see most movement failures due to lack of oil... but there are ones now and then whose cam pin and star slot obviously went through alot of sufferring.
Removing the taper isn't really necessary... you can shorten the shaft...removing the knob and then "fix" the shaft at the correct tension amount. The downside is that different film brands do require slightly differing tension settings to achieve the best results.

Mark

Posted by Nicholas Stevens (Member # 4692) on 03-03-2008, 11:28 PM:

OK so I tried to set the tension on all the projectors here and I kinda ran into a problem. I can't get the tension bands to be able to be set on anything below 3 on some of the projectors without the gate having to be so tight that they won't close and lock. Is it possible for the tension bands to be stretched or need replaced because of the excess tension that was placed on them before?

Posted by Steve Beverly (Member # 4540) on 03-03-2008, 11:34 PM:

quote:
Dudes...
I find that line absolutely hilarious [Big Grin] ! With the amount of unsteadiness we typically see in the crapo release prints of today I am finding more and more Simplex's, Century's, Christies, Norelco's, etc., whose gate tension is turned all the way up in an effort to get something stabilized on the screen.

Mark

quote:
How much should we be willing to alter our practices due to lab errors? What if release prints start to come out all with the same misprinted SR*D tracks what becomes correct? To calibrate the readers to pick up the misprinted tracks or to achieve Dolby spec.? All in all I think the labs need to get their acts together.

What exactly are the problems the labs are having, what are they doing wrong and what can be done to correct these mistakes? ( I ask this as we are getting ready to process and print our own work and would like to avoid the mistakes some of the larger facilities are apparently making.) [Cool]

Posted by Monte L Fullmer (Member # 2797) on 03-04-2008, 02:03 AM:

quote: Nicholas Stevens
I can't get the tension bands to be able to be set on anything below 3 on some of the projectors without the gate having to be so tight that they won't close and lock. Is it possible for the tension bands to be stretched or need replaced because of the excess tension that was placed on them before?

..did we ever get what model of Simplex you have there? wonder if that adjuster got wigged out somehow for you to say "below 3", for 1 to 3 would be lesser tension than from the 3 to 5 position.

Sorry, bands don't stretch being steel, just get thin in the middle.

Posted by Mark Gulbrandsen (Member # 72) on 03-04-2008, 04:28 AM:

quote: Steve Beverly
What exactly are the problems the labs are having, what are they doing wrong and what can be done to correct these mistakes?

Its mainly because they print and then process at Warp Speed 7! Eliminating greed is the only way to fix the problem...

Mark

Posted by Louis Bornwasser (Member # 3063) on 03-04-2008, 05:50 AM:

Once tensions are too high for too long, then the intermittents are fried. This is operator induced intermittent failure.

Replace the intermittents!

(While it is true that some projectors/intermittents leak more than others, we have a slow leak problem with Simplex. On Century, a careful intermittent overhaul will result in an intermittent that will only require a top off every 90 days or so. (One plex waited 13 months and only lost one intermittent; one leaked faster than the rest.)

We do not see lack of oil so much since we reduced the leakage, but we do see excess tension every day.

With reduced tensions, 25-50 years is possible on a Century. Louis

Posted by Tim Reed (Member # 137) on 03-04-2008, 06:57 AM:

Louis's group absolutely does the best (and quietest) intermittent rebuilds on the planet! His intermittent guy grew up in the watchmaking business.

quote: Markie G.

That's funny. It must've taken you all day to come up with that.

Posted by Mark Gulbrandsen (Member # 72) on 03-04-2008, 04:59 PM:

Tim... Less than one second actually....

Monte...

Actually spring steel does indeed stretch.. it also looses its temper over time from both heat and from being stretched repeatedly as in a clock spring. If you think in terms of a clock spring(Yes Tim... I also have a clock making background! Monte has seen some of them...)it can only be wound and unwound so many times over the years before it begins to loose torque. This is because the repeated wind and unwind causes the temper to break down and eventually the metal weakens(and the spring may even break) With less torque then the clock either doesn't run as long or it doesn't keep time as well because there is not enough constant tension against the escapement. Similar things happen to the trap bands if the tension is left turned up all the way for very long periods of time... on just about all machines with bands the equalizer spring will buckle permanentley and the bands will stretch somewhat as well.

Mark

Posted by Ron Funderburg (Member # 4561) on 03-05-2008, 02:58 PM:

As general rule I replace tensions bands every other year weather I think they need it or not. If I can't achieve a good stable picture with tension setting below 5 (and there is no problem with the intermittent) I change them as well no matter the age.

Posted by Nicholas Stevens (Member # 4692) on 03-05-2008, 05:19 PM:

I have the gate's adjusted to be as tight as they can be with still being able to close and lock correctly and the tension knob still has to be set at or above 3 (1 to 5) for the film to be stable on screen. so i just ordered all new tension bands for these projectors. I'm going to change them out and see if I can't get the settings below 3 on the knob and if all goes well be able to loosen the gate up some also.

(by the way, they are the simplex 1060's)

Just outta curiousity, how hard is it to rebuild the intermitten's? Is it something that can be picked up easily or no?

Posted by Mark Gulbrandsen (Member # 72) on 03-05-2008, 06:35 PM:

quote: Nicholas Stevens was the last to post

Apparently it helps if you also know clocks [Wink]

. Rebuilding an X-L intermittent is relatively easy but it does help to have a bore gauge to mesure both the cam shaft bore and star shaft bore to ensure proper oil clearance and that the holes are still round [thumbsup]

. With grind house movements or movements that have been abused the front cover bore wears to an oval... Simplex 35/70 is the worst for wear with a very short movement life if you run alot of 70mm... A friend ran Sound Of Music on his "Howard Straight" Simplex 35/70's for about a year and had to change movements once during the run.

Mark

Posted by Monte L Fullmer (Member # 2797) on 03-05-2008, 08:48 PM:

quote: Mark Gulbrandsen
Simplex 35/70 is the worst for wear with a very short movement life if you run alot of 70mm...

..probably both situations that you mentioned is due to the cast iron INT cover used without any pressed OILITE bearings to support the starwheel in the cover itself and the stronger torque needed to pull that wide film through the trap (prob why the "JJ" unit was a lot better in handling film than the XL-35/70 unit-just can't imagine running 70 in an XL the way how compact that machine is compared to the Century)?

Interesting that a XL movement was designed to do both film sizes without any enhancement for the larger film - or at least some sort of compensation where the assembly can handle both film sizes on an equal basis.

Yes, Mark, those clocks were neat and I did forget about the spring steel tension getting weakened with time ....

-Monte

Posted by James Westbrook (Member # 3690) on 03-06-2008, 01:28 AM:

To me, intermittent movement rebuilding is like having an automatic transmission rebuilt: Best be done by a professional. Most of the fellows here can rebuild intermittents. I can't.

Posted by Monte L Fullmer (Member # 2797) on 03-06-2008, 01:46 AM:

yep, that's for sure - you really gotta know what you're doing when rebuilding those units. I've done a bunch in the past - from taper pinned Super Simplex movements to the XL movements...almost like tuning up a car with all of the diagnostic whoopla attached.

Posted by Mark Gulbrandsen (Member # 72) on 03-06-2008, 07:25 AM:

quote: Monte L Fullmer
almost like tuning up a car with all of the diagnostic whoopla attached.

Ahhh, so you use a Sun Scope to "tune" your intermittents.. I never thought of that. You could see dwell time, pull down, etc...

Mark