Adjusting Kelmar Take-Up Clutches

[Jim Cassedy]

Earlier this week, I converted my JJ's back to 35mm after several days of 70mm
shows, and, of course, one of the steps in that process is to re-adjust the feed &
take-up spool arm clutch tensions. I've done this dozens of times without any issues.
But this week, I just could not get the take-up on one projector to run smoothly.
It takes up a 2K reel of film just fine, once it gets going, but at start up, there's a
slight hesitation before the reel starts rotating. You can't really see it, but if I
manually 'stall' an empty reel with my hand, I think I can feel the a slight
momentary difference as the clutch revolves, no matter how much I tried
"playing around" with the clutch. That night I was going to be running an older,
somewhat brittle (and positively pink!) acetate print- - and this slight' bump'
snapped the leader twice during run-down after threading, despite the fact that
I had tested the take-up several times with another old reel of junk film after I
had changed the over to 35mm. Unfortunately ,that afternoon I was also dealing
with a major projector problem in another auditorium, so I didn't have alotta time
to work on the take up before my show, and so I wound up doing every change-
over to the Film-Tech Forums projector on my knees, so that I could give the take
up reel a slight 'hand-spin' at start up to avoid snapping the leader.
That was OK for the film, but not so much so for my knees!

That other auditorium is still 'down', and so I'm going to be at the theater all
day waiting for the arrival of some parts and a 'certified Sony tech' to get
it going again, so I'm going to tackle my take-up troubles to pass the time.
It's been years since I've disassembled one of these slip/disk friction clutches,
- - Any suggestions? I should also mention that I had lubed both machines
just before my 70mm run last week, and I suspect it's possible some oil
dripped down on to the take-up thingy and that's what's causing my trouble.
These are the fairly common KELMAR 35/70 reel arm assemblies that I've
seen on attached to dozens of JJ's , so I'm sure some of you have some hints.
THANKS

[Mark Gulbrandsen]

Just follow the basic instructions below, and be sure the felt pads are lubricated. If the oil has all dripped out, then take up tension might be uneven... The instructions below are in the Warehouse.

"Page 2
5) Position arm (4) to ensure proper clearance for the reel relative to the pedestal or console, the front wall and all wiring
devices. Apply substantial torque to the primary support screw (17) and the locking set screw (14).
6) See that the film is centered on the reel and that equal pressure has been established by the film on both sides of the last
hold back sprocket. Now tighten the hardware supporting the lower mounting bracket (15).
7) Position the Rounthane belting over the, drive pulley of the sound— head and the take-up clutch pulley. Mark the belt and
cut it
314” shorter than the mark. Press the belt ends together on the connecting link and check its operation under load.
If the belt runs with a belly in the return leg, remove an additional 1/2” at a time until it tracks smoothly. Installation
drawings, Figure No. 4, shows the procedure for putting the finishing touches on the belt splice after final sizing.
In some situations, where the pitch is extreme, the use of a belt tightener roller assembly, Kelmar Part Number 720320,
will prevent abrasion of the belt by the sound head casting or related hardware.
Adjustment and Lubrication
Final tuning of the arms will result in system performance free from film damage or accelerated wear on sprockets. Refer to Figures No.
1, 2, and 3, while carrying out the following steps.
Thread the projector with a full reel of film. Start the projector and carefully check the film path at both the upper and lower constant
speed sprockets. The mounting holes for the upper and lower arms are oversized to provide clearance for lateral and rotational
adjustment. The film should enter and leave the projector squarely with respect to the sprocket, while maintaining a clear and balanced
profile on the feed or take-up reels.
Clutch pressures should not be excessive. Set the upper tension so that a full reel of film will rotate smoothly and without bounce. Heavy
drag on the upper clutch will encourage stress on the film and the upper sprocket assembly, as the reel of film becomes smaller.
When using large diameter take-up reels9 they must be of the “floating hub” design. Check all reels to verify that the hubs are free. A
small quantity of pure silicone spray lubricant between the hub and the reel flanges will help.
Take-up clutch pressure should be just enough to ensure uniform and consistent wrap of the film on a full reel. Excessive pressure will
encourage under- cutting of the hold back sprocket and introduce undesirable deformation and abrasion of the film.
All rotating components ride on pre-lubricated ball bearings and will provide many years of service without maintenance. The felt clutch
disks have been given an initial lubrication at the factory with SAE 40 non-detergent oil. It is suggested that the clutches be cleaned and
examined periodically. When lubrication is required, the use of a heavy non—detergent oil is suggested. Do not over oil.
Rounthane belts should be cleaned periodically with a clean towel.

[Jim Cassedy]

Thanks Mark. I didn't realize there was a Kelmar document in the Warehouse.
This is the twonky take-up that needs some TLC. As U can C, I don't have
Roundthane™️ belts here. (Can they even handle 70mm loads? I don't even
think I've ever seen one on a 70mm setup, but I might have not noticed)

MyKelmarTakeUp.jpg

[Brad Miller]

That Kelmar document is old. You can use Roundthane, but I strongly advise against it. I have seen FAR too many damaged prints when that junk breaks. The V belt you have is far superior and will never break.

When you converted back to 35mm, you did not alter the angle of the takeup arms, correct?

To further clarify so we can all understand the exact scenario, you are threading way ahead of the starting frame and turning the projector over several (or more) frames until the takeup tension tightens up and THEN (assuming the print doesn't have short leaders) using the projector motor to run down the excess leader to the starting point, correct? In other words, you are not threading, advancing 2 or 3 frames and then trying to start without giving the takeup ample film to "start grabbing", correct?

I presume this is repeatable, as in if you put a short roll of junk film in the machine you can start, see the tension loosen and then tighten, stop the projector, repeat, repeat, repeat. Correct?

Also do you have an inverter-controlled ramp-up, or just a slow start kit or nothing on your projector motor? If an inverter, do you know what the ramp-up timing is set for?

[Jim Cassedy]

FOLLOWUP! - First I'll answer some of Brad's questions:

BM: When you converted back to 35mm, you did not alter the angle of the takeup arms, correct?
JC: Correct. The take-up arm was not moved.

BM: You are threading way ahead of the starting frame and turning the projector over several (or more)
frames until the takeup tension tightens up and THEN (assuming the print doesn't have short leaders)
using the projector motor to run down the excess leader to the starting point, correct?
In other words, you are not threading, advancing 2 or 3 frames and then trying to start without giving
the takeup ample film to "start grabbing", correct?
JC: Also correct

BM: I presume this is repeatable.
JC: Yes- - it is repeatable, but the starting 'hiccup" on the take-up wasn't consistent every time

BM: do you have an inverter-controlled ramp-up, or just a slow start kit or nothing on your projector motor?
If an inverter, do you know what the ramp-up timing is set for?
JC: Unfortunately, the projectors here do not have any sort of inverter or slow start on them, but in addition to
turning down the projs by hand after threading I have a rocker switch that I can use to sort of "jog" the projector
a few frames at a time. I really wish I had a slow-start or inverter here, but these motors aren't 3 phase. A few
months ago, at the Telluride Film Festival I was running a rare archival print they were worried about, and I put
a full 3.5-second ramp-up into the inverters there. (and adjusted my change-over threading point accordingly)

Fortunately, the old/brittle acetate print I had this issue with the other night still it's original extra-long lab
leaders on it, and it also had somehow managed to escape ever being plattered, so even the countdown
leaders were uncut! Amazing! So the two film film breaks I had, although unfortunate, were ahead of the
"START" marks on the Academy leaders.

THE FIX:
I spent most of my time on Friday helping the theater recover from an IMB failure that had shut one of the
auditoriums down for 2½ days. But even though I was heading into a 12hr work-day, I didn't want to deal
with this problem over the weekend so I hung around an tackled the take-up tension issue.
I totally disassembled the take up and there were several obvious gummy globs of some sort of 'grunge'
on the surface of one of the metal slip-disks. (The disk closest to the threading side of the projector)
It did not appear to have come from the surface of the friction pad, but more like perhaps some dust of 'film
fuzz' had worked its way into the take-up clutch assembly and deposited itself on the metal diskthingy.

Unfortunately, because I really wanted to get this job done & go home I didn't think to stop and grab some
pictures, but think of it as if you had smeared a couple of globs of rubber cement on the disk, and then let
some dust collect on it and get semi-hardened. That explains why if I held the take-up reel by hand, I could
feel an uneven pull in the tension. (It was as if you had a drive belt with a slight flat-spot in it)

So, I cleaned both of the slip-disks with with alcohol and also cleaned off the friction pad, and then put
a little oil on my finger and lubed the pad and disks slightly and put it all back together, and I ran ½ a reel
of old trailers, starting & stopping multiple times and I'm really happy with the way the take-up runs and
'feels' now. At that point it was approaching dinner time, and I hadn't even stopped for lunch yet, so I just
wanted to get out and go home. I've got to go in on Sunday to work some stupid party event, so I'll do a
few more tests while I'm there, but I'm pretty sure I've fixed the problem.

Somewhere I recall once seeing an actual figure for the amount of pull-torque for a 35mm take up. When
I first was starting my projection "career," I remember watching an old projectionist adjust the take-up torque
by securely taping foot or so of old leader to the hub of the reel, and attaching the other end to the hook on
one of those small spring operated 'postal scales', and measuring the number ounces of "pull" on it.

(And about that phrase "old projectionist"- - Ironically, I'm probably older now than that guy was when
he showed me that trick at least 40 years ago. . so now, < I'm > the 'old guy" )

[Jesse Crooks]

The SMPTE spec for 35mm film is 1.7 to 4.4 Nm. I don't know how to calculate that on the take-up clutch since it's driven, but it's very easy to measure on a feed clutch with a spring scale. I take some scrap polyester leader, fold over the end (with the perfs of both layers overlapping) and splice the two layers together. I put a string on it and attach a spring scale. Test it with an empty reel and a full reel to check the max and min. There's no reason to tape it down... just use a tension wind.

In terms of the "diskthingies" Kelmar calls the fixed plate the face plate and the rotating plate the pressure plate.

[Steve Guttag]

On the takeup, same procedure but you turn the projector on. Check it with an empty reel and with a full reel.

[Ryan Gallagher]

What is the SMPTE spec for 70mm film out of curiosity?

Also anyone know a good model spring scale that has the ranges needed for both 35 & 70. I found this one up to 5N max.
https://www.coleparmer.com/i/ohaus-8002-pn-pull-type-hanging-spring-scales-1-12lb-x-04lb-5n-x-0-2n/1110036

[Ryan Gallagher]

I nabbed a couple cheap amazon options for now:

1N to 30N set
https://www.amazon.com/dp/B08GM1SP1C

[Jim Cassedy]

That's a really nice little set of scales! I'll probably order some next week. They will come
in handy when I've got to go from 35 to 70mm and back again. I've usually done it mostly
by 'feel' and experience, but it would be nice to have instruments to quantify the T-U pull.
But for the moment, I'm really happy with the way the take-up is functioning now after I
cleaned & lubed it a bit. I had another old acetate print to run earlier this week, and had
no issues on start-up. Next week we're running ANORA, mostly in 35mm, although that's
a brand new, print from the lab, (it arrived yesterday) which shouldn't give me any problems.

[Ryan Gallagher]

That's a really nice little set of scales! I'll probably order some next week. They will come
in handy when I've got to go from 35 to 70mm and back again. I've usually done it mostly
by 'feel' and experience, but it would be nice to have instruments to quantify the T-U pull.
But for the moment, I'm really happy with the way the take-up is functioning now after I
cleaned & lubed it a bit. I had another old acetate print to run earlier this week, and had
no issues on start-up. Next week we're running ANORA, mostly in 35mm, although that's
a brand new, print from the lab, (it arrived yesterday) which shouldn't give me any problems.

New prints for everyone!!! What era are we in again? I've got brand new "The Brutalist" 35mm coming up. Will be the Paramount's first run on 6K 35mm reels since god knows when.
They were angling for their 70mm prints but I guess print transit logistics wasn't in the cards.

Also screening Rodruguez's studio print of Dusk Till Dawn. Essentially an un-played vintage print. Had to cut the locks off the cans.

[Jesse Crooks]

I guess you just run it momentarily and shut it off before the scale goes flying? That's the scenario I imagined, and why I've never tried it.

On the takeup, same procedure but you turn the projector on. Check it with an empty reel and with a full reel.

[Jesse Crooks]

I like to use a 5Nm scale for general use and a 10Nm scale for when it's either way off or when attempting to diagnose an issue with the clutch that is making it drag at points in the rotation, which puts it over the max of the 5Nm scale.

[Ryan Gallagher]

I like to use a 5Nm scale for general use and a 10Nm scale for when it's either way off or when attempting to diagnose an issue with the clutch that is making it drag at points in the rotation, which puts it over the max of the 5Nm scale.

I had a 5N and 10N ordered before I saw the set for cheaper. ;-)

[Ryan Gallagher]

SMPTE specs aside. I had email advice from brad regarding the relationship between rewind tension and takeup tension. Essentially takeup should be the tightest wind in your booth, and then rewind should be somewhere in the middle below that. This is to avoid cinch scratches on the rewind bench. His advice for feed tension was it should be the loosest of the 3... so loose that it almost wants to overspin, but main point being that it's tension is lower than your rewind bench, again to avoid cinch scratching.