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Topic: Damage when projector is left closed?

David Buckley
Jedi Master Film Handler

Posts: 525
From: Oxford, N. Canterbury, New Zealand
Registered: Aug 2004

posted 09-09-2005 01:22 AM

quote: Mark Gulbrandsen
... I can't believe the concern over spring conpression on this thread. One might be concerned if one only ran on weekends and just a few shows at that...

ooh - thats me then. On a Century clone, what should one do?

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004

posted 09-09-2005 02:44 AM

Keep the trap closed then on that Clone - be it a Monee, or a Westrex you have. - Monte

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 09-09-2005 10:23 AM

I always insist that projectors be run for about 5-10min before they are threaded at the beginning of the day to get oil pump through the machine and belts to loose any set developed overnight

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 09-09-2005 11:33 AM

At the Grandview drive-in, we always ran the unlaced projectors for about 10 minutes prior to the evening's shows. Especially important in the cool spring and autumn months.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 09-09-2005 03:33 PM

quote: Gordon McLeod
I always insist that projectors be run for about 5-10min before they are threaded at the beginning of the day to get oil pump through the machine and belts to loose any set developed overnight

This is far more important that opening the trap and pad rollers at night!!! This in fact is the ***BEST POINT MADE*** in this whole thead so far. Not only do belts take a set but the grease in ball bearings, oil in movements and shafts also falls back to the bottom of the bearing, sump or movement. A 10 min run in and intermittent shaft oil spirals, sprocket shaft oil spirals all get pre-oiled and brought somewhat up to normal operating temperature in this time. This film of oil will prevent a ton of wear on these critical parts and they will last far longer.

The above example is one of the best examples I've seen here in ages of the difference in thought of a well seasoned "Chief Projectionist" and someone that just claims to be one or was handed the title [thumbsup]

.

Mark

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004

posted 09-09-2005 03:44 PM

quote: Mark Gulbrandsen
A 10 min run in and intermittent shaft oil spirals, sprocket shaft oil spirals all get pre-oiled and brought somewhat up to normal operating temperature in this time....

...and why I hate lacing up the night before for this very reason. We can also include the platters on this - "warm" them up a bit by letting the motors spin and get the tires back to round, especially the AW3 units.

One laces up the night before, faces a risk that something MAY not take off. And if that happens, then you have a mess to unlace the machine and platter and find a way to move that print to another deck if the ring has already been pulled, epsecially if that theatre doesn't have a "pizza board" to move the print.

Why make hell for yourself each opening day....

(Then, I heard of idiots saying by turning on the bulb for a couple of minutes "warms" up the bulb for the day. I put a screeching halt to that one real quick.....)

thx-Monte

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Dustin Mitchell
Phenomenal Film Handler

Posts: 1865
From: Mondovi, WI, USA
Registered: Mar 2000

posted 09-09-2005 10:03 PM

I'm confused about something here. The consensus seems to be that running the projectors for 10 minutes at opening reduces wear....but how? What's the difference if the projector is run for 10 minutes with or without film in it?

I can see the reasoning for perhaps getting a steadier picture by doing this but I'm confused about how exactly it reduces wear.

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 09-09-2005 10:14 PM

My analogy is one shouldn't get in their car and start the engine and drive out with out letting it run for a few minutes first to warm it up especially on a cold day and a projector is built to much tighter tolerances

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Daryl C. W. O'Shea
Film God

Posts: 3977
From: Midland Ontario Canada (where Panavision & IMAX lenses come from)
Registered: Jun 2002

posted 09-09-2005 10:42 PM

Putting more load (as in making it pull film) than necessary on a machine before it lubricates itself and gets to its normal operating temperature is always going to create more wear than the little wear you'll cause by "warming up" such machine while unloaded.

Anyway, as Gordon said, in addition to getting the oil moving, belted machines get any belt set out of them before an increased load is put on the belts. This will (1) make your belts last longer and (2) give you time to change the belt if it breaks as belts are far more likely to break after they've been idle and set than any other time.

Anybody that works for me that refuses to warm up a machine won't be working for me very long.

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Dustin Mitchell
Phenomenal Film Handler

Posts: 1865
From: Mondovi, WI, USA
Registered: Mar 2000

posted 09-09-2005 11:06 PM

The car analogy doesn't make much sense to me. When you put your car in gear and drive it the engine is under the extra stress of 4,000 pounds it has to move. Higher tolerance or not a projector isn't under nearly that much stress. How much extra load does pulling film through a projector create though, especially on a platter machine?

I mean, if I'm wrong I'll accept that no problem, but honestly how much more stress doe the gears/belts have on them with film running through the projector as opposed to without?

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Daryl C. W. O'Shea
Film God

Posts: 3977
From: Midland Ontario Canada (where Panavision & IMAX lenses come from)
Registered: Jun 2002

posted 09-09-2005 11:09 PM

Depends on the design of the machine and its intermittent. To find out you just have to listen to it with and without film.

Even if there were no difference, you'd be far better off to have something break, either a belt of gear tooth, without film in the machine.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 09-10-2005 04:25 AM

quote: Daryl C. W. O'Shea
Anyway, as Gordon said, in addition to getting the oil moving, belted machines get any belt set out of them before an increased load is put on the belts.

Well, Daryl, there is one exception to that one... the RCA Penthouse! The belt set-in is going to be so bad in that POC that you will need a new belt with each show!!

quote: Dustin Mitchell
The car analogy doesn't make much sense to me. When you put your car in gear and drive it the engine is under the extra stress of 4,000 pounds it has to move. Higher tolerance or not a projector isn't under nearly that much stress. How much extra load does pulling film through a projector create though, especially on a platter machine?

Dustin,

Well, Not running a machine first hand unloaded DOES create extra wear. New US built machines typically run with .001" of tolerance or less in the intermittent.... thats the only area of any "real" tight tolerance in US built machines other than the sprockets, the rest is as sloppy as it gets...really! There are European machines that DO run tolerances of .001 on sprocket shafts, oil pumps, etc.... and many of the well made European projectors like the Phillips and Bauer projectors had manufacturing tolerances of 1 micron on some of the intermittent parts. Now thats ***extremely*** tight tolerance and quite amazing craftsmanship and also why many of these projectors are still in use today and very popular!!

At LaVezzi Precision where all the stars and cams are made for US built projectors the final grind on the slot is so very slight that these grinding operations are carried out in sound proof rooms and the grinder spindles run on air bearings!! The operator at most hears a slight tick when the wheel passes through the slot, many times there is no sound at all that is audible. The star is indexed to the next slot by a super high presision jig that LaVezzi custom built in their shops... All jigs like this have to be custom made to achieve this sort of high tolerance... ya can't buy this tooling off the shelf! A tour of LaVezzi is without doubt the most amazing tour that a film technician can go on and you can't begin to appreciate the quality that goes into each part they manufacture without seeing it done first hand.

When compared to a car engine some of the parts in an intermittent are proportionately under as much stress as some parts are in car engines. In a Simplex for instance you have a cam pin that is just .1" in diameter running in a slot thats also just .1" in size when new and you develope perhaps .0001 extra for some oil film in there to lubricate the pin and slot. After many thousands of hours this is the place that a movement will show the most wear and sometimnes you will hear noise generated by a loose fitting cam pin as a very audible annoying clickity clack, a really worn Century movement can actually sound like a machine gun!! The slot and pin are considered no tolerance parts at manufacture but with proper run in these parts DO develop just enough clearance for an oil film to lubricate them. Also the machining marks developed from grinding the slot in the star also assist in carrying oil to libricate this almost zero tolerance part. So not only is there basically no clearance but there is ***BARELY*** any clearance for ***ANY*** oil to cushion these parts. This is the main reason why its imperitive to use the correct weight oil!! On top of all this you have the odd angles of attack that the pin is at whilst the pin is traveling though the slot and pulling the typically 6 to 10 oz pull down load of ***EACH*** frame of film ..... and this is happenning 24 times a second!! On a really worn star its easy to see where the points of maximum load occur because the walls of the slot actually develope waves in them! Whilst the star wheel is at some of its extreme angles the equivelent weight increases and can be the equivelent to pulling hundreds of pounds equivelent weight in an fraction of a second. So without any film of oil present on shafts, spirals and the cam pin they essentially run dry for a 10 to 15 seconds whilst doing the job of pulling hundreds of pounds!! Keep in mind that the 100's of pounds is an estimate on my part but I doubt that anyone here wold dispute that figure... I'm not a mathamatician but I believe that Daryl would get that answer if he ran the problem through his Eniac Computer!!

BTW: a platter fed machine does place ***LESS*** stress on feed and holdback sprockets and their shafts than does a properly operating reel to reel system running the typical 1 hour reels(sorry Steve G. but this is true). A properly operating large reel transport such as a double mut places about the same operating stresses on sprocket shafts and sprocket teeth as a platter system does.

Hope this helps but I've probably got you really confused now....

Mark

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Dustin Mitchell
Phenomenal Film Handler

Posts: 1865
From: Mondovi, WI, USA
Registered: Mar 2000

posted 09-10-2005 05:53 AM

I got all that, and thank you for the info. I knew that projectors were built to very fine tolerances but I had no idea.

Daryl's point about things breaking without film running is certainly valid. Honestly its not that much extra work to do dry runs on the machines. Assuming you power up at the console you could start each one as you powered up the projector. By the time you powered up the last projector the first one would have run long enough and be ready to load.

Anyway, just as a general point of curiosity I still gotta wonder how much extra stress the film running through the projector really causes. Is there any data on this?

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 09-10-2005 07:17 AM

Even the few ounces of back tension the film puts on the intermittent sprocket translates to some pretty severe forces on the starwheel and cam pin.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 09-10-2005 08:20 AM

quote: Dustin Mitchell
Anyway, just as a general point of curiosity I still gotta wonder how much extra stress the film running through the projector really causes. Is there any data on this?

There would be a huge number of different factors to combine into an aquation to determine this. That equation would probably fill several blackboards by the time you were finished! From back tension, duration of pull down, metal hardness, size of the parts involved, the time pull down takes, the differing angles of which each angle would of course have its different wmount of induced force so that part would be logrithmical, etc. A heck of alot of factors wold be in that equation! Let us know after you've worked it out [Wink]

quote: John Pytlak
Even the few ounces of back tension the film puts on the intermittent sprocket translates to some pretty severe forces on the starwheel and cam pin.

John,

You're amazing. You translated exavtly what I was trying to say above your post into just one understandable sentance [Razz]

!!

Thanks,
Mark

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