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Posted by Frank Angel (Member # 248) on 06-05-2003, 12:48 PM:
 
I had something very odd happen in the last two weeks. The rollthane belt on one of my projectors broke. It was a clean break, as if someone had cut it with a knife. OK, thinks me, material stresses out and breaks. But then a week later I am running THE PIANIST and low and behold I walk back into the booth from the rewind room and there is a pile of film on the floor. The rollthan belt on the second machine had snapped also. This, as I said, within a week of the first mishap and the break was as the first, clean as a whistle.

What's going on here? The belts are not too tight and they have been running without incident for a dozen years or so. All I can think of is that I used a solvent cleaner on them a few months ago to keep oil off them. Is it possible that a solvent like 1.1.1. Trichlorethan (and forgive me if I am not spelling that correctly -- or rollthane for that matter) can weaken the composition of the plastic?

Never had any trouble with the old leather belts. I am thinking of going back to them if this plastic stuff is not reliable -- it's pretty, but of no substance! Perhaps they shouldn't have tried to fix something that was working just fine. Or is the leather belting another PETA issue? How many cows have to die for your to run your projectors?

Frank
 

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Posted by Brad Miller (Member # 2) on 06-05-2003, 01:12 PM:
 
I'm not Steve Guttag, but in my opinion if you've got 12 years out of those belts, they are due for changing anyway. I've never seen a Roundthane belt last that long.

I don't know if trichlourethane would damage them or not, but from the sounds of it the chemical does. Steve will know. I understand the clear belts have a better life than the yellow belts. I've never done any personal testing though.

Why do you not have some form of failsafe? Even in a manual changeover booth, in this day and age it doesn't make sense not to have one. Ya gotta go crap sometime and you want some kind of protection before the takeup craps on you!
 

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Posted by Christopher Seo (Member # 7) on 06-05-2003, 01:49 PM:
 
I didn't imagine those plastic belts could last 12 years, either! I'm trying to set up a schedule for changing out the rounthane periodically, so any input as to how often you changeover projectionists replace your takeup belts is appreciated.

BTW, Frank, where did the break occur? The only spot I could think of to break so cleanly would be the point where the barb digs into the rounthane.
 

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Posted by Jonathan M. Crist (Member # 413) on 06-05-2003, 02:22 PM:
 
I have had the same roundthane on my two projectors (6,000 foot automated changeovers) for 15 years. Never have had a problem. They look and perform as good as when they first installed 15 years ago.

Before that I used to used standard auto "v" belts because the leather just would not take the rack from the stress and strain of the 6,000 foot reels.
 

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Posted by Jeff Taylor (Member # 443) on 06-05-2003, 02:24 PM:
 
Ditto Brad's comment...I've had excellent results with the clear belts.
 

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Posted by Dick Prather (Member # 1136) on 06-05-2003, 03:21 PM:
 
Frank,
I have also had problems as you describe using the yellow belts (Roundthane). Some places lasted only a couple of years and others several. When they broke it was like old wire insulation does when you bend it. The belt seemed to reach a time when it was just shot and would break everytime you fixed it. The blue belts (O-Thane) were worse. Not sure if I have the names reversed.

I have had good results with the clear belts form Wolk. It uses the same barb to fasten it. Some of those are over 5 years and going strong on 6000' reels. They sell it by the foot with barbs extra.

The best is a V belt for long life which you should be able to get from any good auto store. Most take up's were set up to run them and Simplex even had part numbers for them. I am sorry I don't remember the sizes. 3/8" leather belt works well also. It was used from the beginning. Getting the staple in right helped. They actuality made a special set of pliers to cut, punch the hole, and set the staple for leather belts. Someone probably still has one somewhere in the NY area. That makes leather real easy to work with
 

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Posted by Scott Norwood (Member # 30) on 06-05-2003, 03:54 PM:
 
I, too, would be interested in knowing if there is a recommended interval at which roundthane belts should be changed. I've never had one break on a projector, but I've had one that constantly broke on an older Kelmar rewind bench. I replaced it and it's now fine.

Do people change these things on a regular basis, or do they just wait until film starts getting dumped on the floor (hopefully not into a puddle of oil)? Roundthane seems to be fairly expensive, so it's not something that one would normally want to change out unless it's necessary.

Yes, we'd all love to get electronic-drive Kinotons where the takeups are driven with torque motors, but that isn't going to happen anytime soon.

And, Brad, I've never seen a manual booth that had failsafes anywhere. I guess that the assumption is that the presence of an operator in the room should be sufficient.
 

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Posted by Sam Hunter (Member # 1119) on 06-05-2003, 04:08 PM:
 
I am using a leather belt that I picked up at the singer sewing machine shop (used in treadle machines) and it seems to work pretty darn good. I am not sure of the size though, I would say it isn't quite 1/4".
On the other hand I haven't ran a whole lot of stuff yet so maybe I need to be carefull, but Hey, I got a failsafe
 

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Posted by Dan Lyons (Member # 1454) on 06-05-2003, 06:09 PM:
 
12 years?!?!

Soft plastics and rubbers tend to get less pliable and brittle over time. It's not very surprising that it would snap eventually.

Danny
 

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Posted by Gordon Bachlund (Member # 124) on 06-05-2003, 06:26 PM:
 
Frank, I really believe you can't beat leather belting for durability. While plastic belting can be solvent welded, good old leather with a mechanical joint lasts and lasts, and oil leaking on it just makes it last longer.
 

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Posted by Steve Kraus (Member # 476) on 06-05-2003, 06:34 PM:
 
Failsafes would require something to hook them up to to kill the motor, close the C/O, and cue the dimmer. I think they would kill shows that didn't need to be killed. Takeup failures are rare enough that they aren't needed. I almost always take up on shipping reels (given that I'm usually only screening a film once) and even as bad as they sometimes are and sometimes they are only holding together because of the shaft clip (I'll use a proper split reel if a shipper is too broken) I can think of only once in recent years that I had a takeup failure due to the reel and once when a belt broke and in both cases manual intervention kept the show going while a failsafe would have killed it.
 

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Posted by John Hawkinson (Member # 1135) on 06-05-2003, 08:26 PM:
 
I've seen varying opinions as to whether you should heat the roundthane around the barb after installing the barb. What are FT opinions?

--jhawk
 

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Posted by Tim Reed (Member # 137) on 06-06-2003, 11:16 AM:
 
Frank, that's normal failure for those, as several folks have mentioned. They'd break very close to the joiner - straight across.

Then, again, maybe you're having union trouble?
 

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Posted by Robert Golding (Member # 746) on 06-06-2003, 04:00 PM:
 
I've had troubles before, so I took the time to measure the length of my belts. I bought your standard one piece v-belt and installed them. I've never had a problem since. It's not as easy as the other types but it will sure take care of your problem.
 

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Posted by Bill Enos (Member # 440) on 06-06-2003, 11:58 PM:
 
I usually get 10 or so years from roundthane. We join them with the aluminum barbed bullet shaped connectors. After about 5 years check them monthly & replace when cracks appear near the join. Connectors pull out of leather and it stretches on 6000 ft. reels, costs a lot more too, if you can find it.
 

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Posted by Steve Guttag (Member # 268) on 06-07-2003, 09:35 AM:
 
First off...roundthane and all its similar like belting is not my favorite. It is too elastic. As a result, take up tension is uneven and often adhesion to the various pullies is less than desired.

If you have a roundthane belt system, take a tension guage and measure the take up tension on a reel (by stalling the reel with the tension gauge)...you'll see the tension gauge bouncing around and often seen the clutch speeding up and slowing down.

My favorite mechanical clutch drive is direct (Noreclo DP-70) and a close second is chain-drive. After those comes the beloved V-belt. With a V-belt you will get a good long life and next to zero problems. Sure it isn't as easy as roundthane but rarely are better things easier to install.

Back to roundthane...

For lack of a better description...they will dry-rot over time and some batches of the stuff (we obtain it wholesale from industrial supply houses) are better than others. We have had to pitch entire rolls of the stuff due to premature splitting.

It can be too hard (dry rots) and will split just with your finger nail or it can be too soft and will split due to the connector barb.

Some tricks of the trade:

Desharpen the barb a bit...it doesn't need to be so sharp. If your old barbs worked well...keep them, the new ones may be too sharp.

Bur the barb....that is put some nicks in the barb so it can not rotate within the roundthane. One of the problems is that as the belt moves about, it will have some slight twisting action which will allow the barb to cut the roundthane like a knife...putting the nicks in will keep the barb from rotating within the belt.

I have not been able to positively prove that heating the connection (to melt the belt around the barb) makes a better join. You can, however, overheat the connection and destroy the belt.

Don't over tension a roundthane belt! The thing already has too much "spring" in it...over tensioning it only stresses it out, not improve adhesion.

While you are at it, keep your clutches in good repair...having the belt put up with a jerky operation isn't good for the belt nor your entire gear-train. Clutch tension should be uniform. Check them often (weekly). Grab the lower reel and turn on the projector. You shouldn't feel a jerky motion from the reel while it is stalled. If you do, cleaning and possible clutch pad replacement may be in order. Some clutches need oil impregnation while others do not. If yours needs oil, then make sure you apply it evenly. After relubrication, you will find that after a weeks worth of shows, you will need to retension your clutch as the oil is squeezed out.

Make sure your clutch is set properly...you only need enough tension to turn your largest reel to the point of no bouncing with a full reel. If you are snapping film or stretching perfs at start off, get floating hub reels, don't turn the tension up to get the reel to come up to speed faster.

Lastly, Scott...you were just at the Kimball Screening room in Williamsburg, VA...where it is a manual changeover system with not one but TWO failsafes on each projector (one entering the upper feed sprocket, one after the lower feed sprocket). So you have indeed seen a manual changeover system with a failsafe...your life is now complete

Steve
 

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Posted by Scott Norwood (Member # 30) on 06-07-2003, 01:33 PM:
 
Steve--good point...I didn't notice the failsafes when I visited. Really nice installation, BTW!

Actually, the Columbus Theatre (see the pic gallery) has a failsafe on one machine, too, but it's only useful when running off the platter.

Why didn't chain-drive takeups become more popular? The Western Electric bases at the Avon Cinema (also has pics in the gallery) are chain driven and I've never had a problem with them. It seems that this would avoid the problem of having the belt slide off the pulley on the takeup clutch, which I have seen happen elsewhere.
 

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Posted by Frank Angel (Member # 248) on 06-07-2003, 02:59 PM:
 
All good points, guys -- and Steve G., master of the reel-to-reel transport, thanks for the tips. You are right -- the "slip as you go" clutch is very susceptible to the variations of oil and dirt, the condition of the pad, etc., and IMHO, the slippage operation is pretty primative in terms of maintaining constant pull force without any feedback control mechanism. Adding even a tensioning arm would be helpful. I do check it periodically. And am always listening for the sound coming from the holdback sprockets. I almost always run 2000ft reels which are not as demanding on the clutch system as are 6000fters.

Anyone remember the clutch arrangement on the old 300 series 16mm B&H takeup arms? The spindle pully was driven by a wide cloth slip belt -- as the reel filled with film, the weight put more pressure on the slip belt and more force was applied to the spindle, yet the belt slipped more. It seemed like a very elegant idea that could especially be applied to 6000ft 35mm reels where there is such a wide range of difference between the force needed with an empty reel and with a full one. The belt design seems like it self-adjusts better than the slipping clutch idea.

As for a failsafe, well, I suppose it would be useful, but as Steve points out, this problem comes around so infrequently, I don't think the danger of it is worth the risk of a failsafe malefunction. Whatever I put in now, the clear stuff or even if I go back to leather as Gordon points out is the best, it will certainly last way past my retirement.

And just for your information, as scary as a pile of film on the floor looks, rewinding it is quite easy if you careful. The film doesn't knot up and tangle like it looks like it would the first time you see such a thing; it simply reverses its "fall pattern" back onto the reel. Because it unfolds gently as it is fed out of the soundhead, no scratching occurs. The only film at risk of picking up dirt are the first few layers on the floor; the rest piles gently on top of it. If you are lucky, the failure happens toward the end of a reel and not the very beginning (mine happend near the end of the reel).

I have seen some guys try to wind the film back on to the takeup reel as the film is running. THAT is very dangerous as you have to pull film from the bottom of the pile with great risk of scratching. Unfortunately some projectionists will do anything to keep from stopping a show. Letting the film pile up on itself is much safer because as I said, you can reverse the process quite easily, rewinding back onto the supply reel. I don't know what you would do with a 6000ft reel other than stop the show.

Even as remote a possibility of a takeup failure like this happening, having one happen to you only once will keep you of a very good mind to always keep the area around the projectors especially clean. And with Simplex, the machine world's equivelent of hitting a Texas oil load, the need to be very vigilant about cleaning that oil drip pan.

Naturally I thoroughly cleaned the reel before it went back (wanna make sure those prints are spiffy-clean when they're put on the bandsaw table!).

Notice: no film was injured in the screening this print!

Frank
 

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Posted by Richard Fowler (Member # 893) on 06-07-2003, 05:35 PM:
 
Simplex did have a takeup arm which worked on a weight compensated clutch set-up which I have not seen in a long time.
The clutch was cone shaped which allowed the spindle to bear more weight as the reel loaded up. Some Kinoton models are happily using chain drives on the take up end
Richard Fowler
Kinoton America Inc.
Miami
 

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Posted by Robert Throop (Member # 61) on 06-07-2003, 06:13 PM:
 
The Clayton takeup was an example of both chain drive and weight compensated tension. The US Army and Air Force theatres still use the XL takeups Richard was referring to.
 

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Posted by Dick Prather (Member # 1136) on 06-07-2003, 07:05 PM:
 
I have XL take up's in my screening room with 2000' magazines. Also in other private rooms I service. They are a cone and clutch type not a disk. For me it is the best belt take up there is. Would not use anything else. Self adjusting based on the weight of the reel and film. It is also supposed to run oiled. The manuals never had any instructions but I turned up the Simplex service bulletins and found the care and feeding of the XL take up. They work just as well with 6000' reels.
 

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Posted by Christopher Seo (Member # 7) on 06-08-2003, 01:19 AM:
 
Frank,

Good point about not trying to manually spin the takeup reel to take up a pile of film. Are you saying you would let the rest of the reel run out onto the pile, leave the feed reel mounted, and wind it all back onto the feed reel?
 

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Posted by Daryl C. W. O'Shea (Member # 1303) on 06-08-2003, 01:48 AM:
 
That'd be the way to do it... wind it back up onto the feed reel. Now whether or not you should knowingly let the last 500 feet spool out on the floor, well that's a whole different topic that I don't want to touch with a ten foot pole!

Only once have I been surprised with a thousand feet of film on the floor as I walked into the booth just before the beginning of the credits (wish I could be in two booths at the same time). Since there was maybe 15 seconds before the credits hit the screen I let the extra 22 feet spool out, but the second the titles hit the screen I stopped it and spooled it all up to the feed reel. All was good... thank goodness for on-line film cleaners.

Luckily my other few run ins with failed takeup belts (of all kinds) have been when I've been in the booth near the machine. You can easily spool ~25 feet back onto the takeup reel while the machine is still running... then sit there for the next 30 minutes winding the takeup by hand... yippee!

In case anybody (lurking) doesn't know... the yellow belt pictured is Roundthane.



Now if you're ever in this theatre, don't go and wipe the oil off of the belts, you'll mess the takeup right up. The adjustment springs are so tight on these machines that the takeup clutch doesn't turn at all. Instead the belt just slips. Incredibly, it gives the most even takeup tension I've ever seen.
 

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Posted by Gordon McLeod (Member # 33) on 06-08-2003, 09:04 AM:
 
Ballantyne Model6 soundheads

I am suprised that the pinion can handle the 6K reel load
 

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Posted by Stan Gunn (Member # 554) on 06-09-2003, 01:58 AM:
 
Roundthane in OZ is orange, I have seen it in use on drive belts and take up over ten years old and no sign of failing.
 

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Posted by Barry Floyd (Member # 385) on 06-09-2003, 09:08 AM:
 

quote:

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Ballantyne Model6 soundheads

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