Film-Tech Forum ARCHIVE: Bizzare Random Upper Reel Problem

This is topic Bizzare Random Upper Reel Problem in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Martin McCaffery (Member # 37) on 01-13-2009, 09:31 PM:

This is a problem that has occurred maybe 6 times in the last 2 years.

During the last minute or so of the reel, we lose the upper loop, and if we don't get to the machine in time, the film is pulled all the way through, from the top down. The only other consistent factor is it only happens when using the film cleaner. And only on one machine.

Simplex 35
6k reel, floating hub. Every time but tonight, only happened with 4 reels loaded on reel. No indication of hub freezing.
Clutch pads have been replaced. dry felt. No indication of clutch freezing
No indication of Cleaner freezing.
No indication of upper sprocket freezing or slipping. A little play, but not more than in the lower, post intermittent sprocket.

I'm stumped. Anyone seen this before?

Posted by John Walsh (Member # 168) on 01-13-2009, 09:35 PM:

Could the upper pad roller arm not being locked down; ie the spring is weak?

Posted by Martin McCaffery (Member # 37) on 01-13-2009, 09:39 PM:

Just checked, not the pad roller.

I should add that the film is being pulled tight, like the upper reel has frozen. Every time it has happened that I've been able to check, both the reel and the clutch rotate fine.

Posted by Brad Miller (Member # 2) on 01-14-2009, 11:42 AM:

Back off your upper arm clutch tension. It takes very little to do the job right. The film does not need to be kept snug on the rollers entering the projector during normal operation. (This might not be your situation, but most people set them too tight.)

Posted by Scott Norwood (Member # 30) on 01-14-2009, 01:38 PM:

What size hubs do the feed reels have?

Posted by Kenneth Wuepper (Member # 1174) on 01-14-2009, 02:21 PM:

I would try to check the bearings on the shaft of the payout magazine/arm. Worn bearings tend to 'freeze up' and cause major drag on the shaft. Those bearings carry a very heavy load when the reel is full. The worn raceway or worn ball bearings can cause the bearing to become locked momentarily causing just the effect you describe.

I have often thought that this would be a great application for needle or roller bearings as they carry a heavier load than the ball bearings.

Lubrication is not an option once the wear is at this point.

KEN

Posted by Rick Raskin (Member # 1561) on 01-14-2009, 02:35 PM:

Sounds like a tension problem to me, either from worn bearings or the tension adjustment itself. With a full reel there is sufficient energy in the motion of the reel to overcome the drag on the shaft, but as the film unloads the energy exhibited by the reel's motion decreases and reaches a point where it is insufficient to overcome the drag. Sound feasible?

Posted by Mark Gulbrandsen (Member # 72) on 01-14-2009, 03:44 PM:

Screw the reel arms! Install anuomation and a platter system instead [thumbsup]

.

Mark

Posted by Sean Weitzel (Member # 244) on 01-14-2009, 04:27 PM:

Bite your tongue! Everyone knows platters scratch film! [Big Grin]

Posted by Brad Miller (Member # 2) on 01-14-2009, 04:59 PM:

You silly people do not need Mr. Guttag and I to start another discussion. [Razz]

Posted by Martin McCaffery (Member # 37) on 01-14-2009, 09:02 PM:

No problems with it tonight, but then the film cleaner was on the other machine, and I did say it was random.
Loosened the tension on the upper clutch and checked the bearings on the upper spindle. They appear and feel fine.

5 inch hub, 26 inch reels.

Getting a platter is fairly low on my list of things to do;>

Posted by Martin McCaffery (Member # 37) on 09-01-2009, 09:03 PM:

Problem started up again in the last couple of days.

It starts with the upper loop losing about one sprocket at a time slowly until there is a total fail, which, if the projectionist doesn't get to it in time, rips up the film.

Still happens apparently randomly, but happened Sunday night and tonight. No problem last night.

The projectionist stopped it just when it started tonight (stopping the show). Re-threaded and started the machine. Immediately happened again. We tried one more time and it ran a couple of minutes and started slowly happening while I was watching it. The bottom loop is not getting bigger, and the fail pulls out the bottom loop, too. This only takes place in the last few minutes of the reel, so by then we were close enough for a change over.

Checked everything listed above. Haven't had the problem since January. All gears and sprockets seem to be fine. Could the clutch be somehow tightening itself?

Totally stumped.

Posted by Steve Guttag (Member # 268) on 09-01-2009, 11:40 PM:

The clutch, depending on style, may need lubrication...you should SERIOUSLY stop using 5x26s...7x25s will not have problems...you'd be amazed at the difference...particularly if you use floating hubs.

Posted by John Hawkinson (Member # 1135) on 09-02-2009, 01:11 AM:

It's a good idea to test with more load than you should ever see, just to you're sure you're good in unfortseen circumstances. In addition to dragging on the reel by hand (with a rag, or whatever), mount a split reel and run film off a 3" core, a 2" core, or even a 1" trailer sleeve.

If you can do handle a 2" core, then you're good for any manner of 5" hub. If you can't, well, lubricate, adjust, etc., until you can.

--jhawk

Posted by Monte L Fullmer (Member # 2797) on 09-02-2009, 01:53 AM:

true .. 5x26 contains a lot of rotational torque when the reel is turning that fast even with slip hub reels with only 5 minutes of film remaining....

Good suggestion in reducing the upper shaft tension to almost nil, or at least a couple of ounces of string tension.

-Monte

Posted by Gavin Lewarne (Member # 5397) on 09-02-2009, 04:06 AM:

i had something similar to this on one of my westars, turned out the gear driving the upper sprocket had a slightly worn tooth, which caused it to slip a tooth when the sprocket was under tension. this caused my upper loop to slowly loose length and cause the problems you describe. i too spent ages altering my clucth tension before i noticed the real cause.

just my 2c

Posted by Steve Guttag (Member # 268) on 09-02-2009, 05:57 AM:

Actually...I've seen that one too! I want to say the phenolic gear was slipping on its hub.

Posted by Martin McCaffery (Member # 37) on 09-02-2009, 09:49 AM:

I've seen gear hub slippage before elsewhere on the machine and it is not pretty.

I've checked all sprockets and gears and have not found anything obvious.

I've backed off the clutch tension to almost nothing. The other machine, which never has this problem, has much greater tension, even though the tension screw is backed almost completely off to spindle. Both are Kelmar arms. but they are slightly different designs. Both have felt pads. Previous recommendation in different thread (from Brad?) was not to lubricate them.

As far as reels, we have what we have. They've worked well 99% of the time. If I could pin the blame on them, I'd change them out.

It is the random nature of this that is so annoying. I can't replicate it, so I don't know if I'm making progress.

Oh well.

Posted by Dave Macaulay (Member # 813) on 09-02-2009, 10:58 AM:

Check the pad roller again, I think. Make sure the spacing is right, dragging a bit on two thicknesses of film and free on one. Check the alignment of the reel and film cleaner, if the film enters the sprocket oddly it can climb up and skip a hole. The reel and film cleaner must be exactly aligned to let the film lie on the sprocket straight and level.

Posted by Bill Enos (Member # 440) on 09-02-2009, 01:28 PM:

After reading this is just tried about 1/2 inch of film on a 2k aluminum house reel, it takes a good bit of drag to loose the loop.

Posted by Martin McCaffery (Member # 37) on 09-02-2009, 03:35 PM:

Checked the cleaner alignment it is ok, but does have a little more play than the other machine.

Checked the pad rollers and reset the second one. The knurled screw on handle was flush against the plastic roller causing extra drag. Didn't freeze it, but did drag it.

We'll see if the problem shows up again.