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Author
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Topic: Why replace bad bearings?
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Monte L Fullmer
Film God
Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004
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posted 04-18-2005 12:33 AM
Simply tell her (on the P35GPS) that the upper, middle and lower constant speed assemblies are about $650.00 apiece if puchased by themselves. Yet, Christie has a repair/exchange program. You order the assemblies needed, take out the old and replace with the new, send back the old and there is some credit (core charge) refunded for the exchange.
Better get those assemblies out for if you don't and a bearing seizes (in which they can do at anytime), you'll have a cold house for while. If a bearing seizes, the machine will suffer some bad damage, thus further repair will be needed and this will not be covered in the repair/exchange program. It's called "insurance."
Ask her on what kind of car she drives. If it's a newer car, or a fancy car, does she "let it go" due to noise since it still runs, or does she get it right in for repair to avoid further damage which will be costly in the long run?
Same goes for the projector. It's a machine as with her car.
-Monte
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Mark Gulbrandsen
Resident Trollmaster
Posts: 16657
From: Music City
Registered: Jun 99
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posted 04-18-2005 08:06 AM
Actually you are all correct however the subject is a bit broader than just bearings.
Replacing assemblies is far too expensive!! For ALOT less money the projector(s) can just be re-bearinged right on site quite easily. I just did 6 Christies a couple of weeks ago, and installed all the new hard coated pulleys as well. Giving each a good clean up I was able to do them in a day and a half total. Its alot less expensive to maintain them this way as the bearings cost but a pittance. The only bearings that actually have any real cost are the sprocket shaft bearings at about 16.00 each and there are 6 of those in each machine. While I have only seen a shaft torn up once it is a rare situation. You will usually find the bearings grinding them selves to smithereens first and the shaft dropping out of alignment. Be sure to use ONLY rubber sealed bearings of decent quality, you'll need a bunch of R-8, R-6, and don't forget the R-118's on the soundhead lateral guide rollers. The R-118's are so tiny they may seize up and scratch a print. If you spin them and they sound dry then they definately need changing. You will need Christies special alignment guage for that job. While you're at it check the lateral guide rollers in the gate, you may find them to be very loose and they will need new adjustment screws, ruby balls, and perhaps even new lateral guides themselves, you'll need that same gauge to align them as well.
All this wear is very typical on Christies and just like any other projector they HAVE to be attended to or the longer you wait things will just keep gettting more expensive to repair. Actually, the P-35 series is about as far from maintainance free as a projector can get but over all they put out dam good images when properly maintained. When a machine has been rebuilt they should also run whisper quiet with the film producing the brunt of the running noise.
P.S. When they are torn down carefully inspect all the pulleys for wear and replace any that are worn even slightly!! Its unusual not to find a worn pulley or two. Belts should and will easily last two years in a P-35 but chenge them yearly to be on the safe side. Also, alot of belt black dust is indicative of worn pulleys... a machine in good shape will not exhibit alot of belt shedding.....
The original bearings that they used had fibre shields and didn't last very long at all, just a couple of years or so. Christie switched to bearings with rubber seals and they typically last 5 to 6 years but probably not much longer. So if yours are older than that then you have some idea that its probably time for an overhaul.
Hope this helps you somewhat....
Mark @ CLACO
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Frank Dubrois
Jedi Master Film Handler
Posts: 896
From: Cleveland, OH
Registered: Mar 2005
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posted 04-18-2005 05:22 PM
Replacing them is out of the question. These units are pretty noisey too. Their about 6 years old. I hear a lot of banging going on, so I took a sample group of bearings out and when I shook the bearings back and forth, you can hear the little balls rolling around in there. The grease is gone. Its a rare find to locate a bearing that is still good. Were looking at a large expense to replace all these (8 projectors in all). We have Jackshaft assemblies that are running on dry bearings, shutter assemblies that sound horrible and the constant speed assemblies had 1 good bearing out of 8 checked...the rest rattled and looked burnt. We are not allowed spares because of the cost and she figures since theyve been running fine so far, the problem really isnt that serious. I fear great problems this summer with all the great movies and our 12 hours day, somethings gonna break.
While on the subject, whats the best way to install bearings? I have a particulary hard time with the shutter assembly because of the strange shape. The previous guy used a screwdriver and hammer (and it shows). I have used old bearings to lay on the new bearing and lightly tap them in, then when their started, I bought a C-Clamp and seat them all the way into the assemby. Works pretty well, but I was also looking at a bearing driver/remval kit except no one can tell me how they work. There are some bearings that absolutely dont want to come out. Oh yeah...when you replace a bearing is it necessary to replace the tolerance ring too? I say why not, she says ADDED EXPENSE. I'm thinking about printing these repsonses out and showing them to her. Thanks again!
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Brian Michael Weidemann
Expert cat molester
Posts: 944
From: Costa Mesa, CA United States
Registered: Feb 2004
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posted 04-18-2005 06:47 PM
Not allowed spares? Is this just for bearings, or for spares of any kind? Now that would just be ludicrous! ![[Eek!]](eek.gif)
It sounds like what, unfortunately, might need to happen is a total failure. Let the bearings go bad, let the system cease to be in "working order" and then when the quite expensive "repair bill" comes for the cold auditorium, let these chains of command think about things like "well, why didn't you fix it before it went bad?"
They might not like it, and they might not change they're way of thinking, but it's nice sometimes to slap an "I told you so" up there; if for no other reason than possibly to earn a little more respect. Hopefully an "Oh, this guy was kind of on top of things, trying to get things fixed. Good job!" kind of thing.
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Mark Gulbrandsen
Resident Trollmaster
Posts: 16657
From: Music City
Registered: Jun 99
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posted 04-18-2005 07:33 PM
quote: Frank Dubrois
While on the subject, whats the best way to install bearings? I have a particulary hard time with the shutter assembly because of the strange shape. The previous guy used a screwdriver and hammer (and it shows). I have used old bearings to lay on the new bearing and lightly tap them in, then when their started, I bought a C-Clamp and seat them all the way into the assemby. Works pretty well, but I was also looking at a bearing driver/remval kit except no one can tell me how they work.
Its VERY good that the previous guy WAS the previous guy and IS NOT the present guy. And its great that you want to attempt to do it the right way!! I carry a No.1 Arbor Press in my service van. They cost less than 30 bucks at Harbor Freight, sometimes just 20 bucks on sale. A tech isn't worth his pay unless he has this tool in his van!! You will also need 2 pieces of 6061 alumnium bar stock 1/4" thick 2" wide by 7 or 8" long with a series of holes drilled into it for the various shaft sizes drilled for just enough clearance for the shaft to pass through, be sure to de-bur the holes. Use this bar or bars as a backing plate.
Using two of those alumnium pieces spaced apart to clear the bearing you want to press out go ahead and press the shaft out of the assembley and then the old bearing off the shaft, press the other bearing out of the block using a deep well socket... also note which way the shaft came out! Using that bar stock with the holes press the shaft onto a new bearing, then press the other bearing into the other end of the assembly. Then place the shaft with bearing in the other side and press the shaft and bearing through the other bearing. When you press on any new bearing you need to press both the inner and outer races together so you don't damage the bearing. The plates with the holes are good for that. If the shaft sticks above the plate place a socket over that to clear the shaft and then press. Some assemblies, the shutter shaft in particuluar require just a tiny drop of loc-tite on the shafts where they go through the bearings bore. You will see it on the shaft when you dismantle the bearings from it. All the assemblys differ but are basically done this way.
For idlers you will need a decent snap ring tool. Simply remove the snap ring then press the bearing out on the press using an appropriate size socket. Using a socket thats the same outer diameter as the bearing press in the new one and replace the snap ring. Don't press on the center race ![[Mad]](mad.gif) ! Have a few extra snap rings before hand!! They can and will boing into orbit once in a while and they ALWAYS land UNDER the projector base or console never to be seen again. Most of the smaller snap rings get lazy and they should all be replaced. Get to know your local bearing dealer very well... explain to him what you need to accomplish. Some bearing distributers have salesman that will call on you. Our local Motion Industries Sales Office does this for us.
![[Smile]](smile.gif) VERY IMPORTANT...Have everything you need before hand to do the job.....VERY IMPORTANT !!!
quote: Frank Dubrois
There are some bearings that absolutely dont want to come out. Oh yeah...when you replace a bearing is it necessary to replace the tolerance ring too? I say why not, she says ADDED EXPENSE.
They WIll come out with the arbor press. Its not really necessary to replace the tolerance rings unless they are in bad shape,were handled by the "other guy", or this is the tenth set of bearings put into the machine. This isn't an aircraft after all!!
quote:
I'm thinking about printing these repsonses out and showing them to her. Thanks again!
Good!
If she were under me I would fire her for letting the equipment get into this poor of condition. Mantainance, if done regularly, is not that expensive as you will never have one large bill as she is aboutn to get. Had that been done by some qualified tech they wouldn't be in this shape!! However, if she is the owner of the place she may know that the $$ is very tight... in fact there may be none for service. BUT if she drives a new BMW and wears designer clothes then its obvious she comes before the projectors. Some day (very soon) she will have a very BAD DAY and will end up with a HUGE projector repair bill ![[Big Grin]](biggrin.gif) .
No need to replace the projectors. They are actually decent machines and you can re-pulley and re-bearing a complete machine for well under a grand. Even the Ultramittent outer ball bearings can be replaced but that IS DEFINATELY a shop job for a tech familiar with that imtermittent. You could also find a servicing dealer(there are still two or three out there in the U.S.!) that can swap out rebuilt assemblies for you at a much lower cost, or make arrangements to send yours in for onernight repair. you'd be down for 3 days with overnight shhipping both ways. If you're in a remote place that might be the better alternative. Stacking prints now for a while is not as big a deal as doing it in the middle of the summer and loosing 3 days of shows per screen.
Mark @ CLACO
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