Film-Tech Forum ARCHIVE: Squeaky Bearing in 5-Star

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Posted by Randy Stankey (Member # 64) on 03-17-2004, 04:10 PM:

The bearing(s) on my sound drum shafts are beginning to sqeak and they have progressively gotten worse over the last few weeks.

I have verified that it's the sound drum shaft bearings that are squeaking:
Projector off. No film in machine. Pinch roller open & out of the way. Gently rotate the sound drum flywheel with my hand. You hear a metalic squeaking sound as it rotates. Sounds kinda' like a little mouse inside there.

Okay. So the bearings will need to be replaced.

If I was working at my old job, I'd call in a parts order and have it repaired within the week. Here, I don't have the $$ resources, nor the scope/RTA handy to just tear the projector apart like that. I'll have to rent the equipment from a local guy. I'm sure you can imagine what the PO/requisition process is like around here. It's like pulling teeth, to say the least!

My questions are:

How long do you think I can let this keep until it shits the bed on me for good?

Do you think it's possible to disassemble it and put some oil or grease on the bearings to passify it for a while? Or, do you think the amount of work that I'd have to do wouldn't be worth it and It'd be best just to replace the whole ball of wax and be done with it?

In the past, the bearings that Strong was using for the 5-Star haven't lasted very long. I have seen several bearings that were replaced and failed again in just a few months. Has Strong improved the specs on these bearings? Should I just order the standard P-2199 bearing? Or, is there a better bearing that I can order?

Oh, and just so you know... We never use any liquid cleaners, or lubricants inside the projector or sound heads. We'll use the occasional Q-Tip dipped in alcohol to clean pad rollers but, since we use FilmGuard, we hardly ever have to use more than a paint brush and a shop towel.

Posted by Matt Zeiner (Member # 1914) on 03-17-2004, 04:40 PM:

I have had spotty luck with repacking them, but if the races are OK, you could try repacking them with Century Grease, or better yet, wheel bearing grease available from any auto parts store. You'll still need to re-align the A-chain. The longer you wait, the better the chance the bearing will score and deteriorate if it has dried out. I never buy bearings from Strong - they are available from just about anywhere that sells bearings.

Posted by Mark Gulbrandsen (Member # 72) on 03-17-2004, 06:43 PM:

Actually those bearings are not supposed to be greased, only oiled. Any grease in them will cause excess drag on the stabilizer and possibly slow it down... it will definately diminish its effectiveness. You should use a synthetic oil of some sort, LaVezzi, Mobil-1 or something of that nature as the synthetic will not evaporate. This was the design of the original 4 star should reproducer and it stuck on the No Atar as well. Only buy bearings with plain shields, not with seals...as the seals will have an even more detrimental effect on loading down the stabilizer. I believe they're 6202's and they should be under 10 bucks each.

Mark @ CLACO

Posted by Adam Martin (Member # 641) on 03-17-2004, 07:00 PM:

What exactly is involved *after* replacing the bearings on the sound drum shaft? I've only ever just replaced the bearings, reinstall the sound drum and go. Everything sounded fine afterward (actually, a lot better with non-rusted bearings!). I even did it between shows once. Did I get lucky on the three or four projectors I've done this to? Was the instructing technician an idiot? There aren't any adjustable parts involved in the process.

Posted by Steve Kraus (Member # 476) on 03-17-2004, 08:16 PM:

Yes, if you accidentally get bearings with grease (it's happened to me and AFAIK this is what the OEM supplied, go figure) you'll need to clean it out, picking out as much as possible with whatever tool is handy then washing them in a solvent before relubricating with oil.

I'd bet you could poke at the thin metal shield with the bearing in place, til it pops off and you cut and remove it. Then a few drops of oil will cure it indefinitely although without the shield it will be a dirt magnet.

Adam, what did you move to get the sound drum out? Solar cell? Reverse scan light source? It seems unlikely you'd get either back exactly where it was before but perhaps you did. If it was just a light source and no digital basement reader was involved you could probably check Dolby level and if the level is what it should be you probably are about where you were. If it was a solar cell this method would probably also get you very close but you'd need to verify by checking X/Y film on a scope. The tiny chance that something changed in terms of the position or skew of the drum would make me want to also look at pink noise on an analyzer and scope to make sure nothing happened with focus or azimuth, more for peace of mind than anything.

Posted by Bob Koch (Member # 1062) on 03-17-2004, 08:25 PM:

Man;whats the matter with you clowns; listen to what Mark has to say; my " CHRIST" grease in a stabilizer bb please spare me this.

Posted by Richard Fowler (Member # 893) on 03-17-2004, 08:38 PM:

On the SH1000 ( older Simplex model )you where suppose to add 1 -2 drops of oil to the ball bearing races a couple of times a year, which if there where proper bearings was pretty easy due to the construction of that unit. It is hard to have a shaft "flywheel" with stiff, greasy bearings.

Posted by Adam Martin (Member # 641) on 03-17-2004, 08:41 PM:

Gee, thanks Bob. Such insightful and constructive advice. [Roll Eyes]

Now that you mention it, Steve, I did have to remove the solar cell (forward scan exciter setup) to get the drum out. It's been a few years now, but I don't remember there being much play at all in the remounting of the cell bracket. Lucky me!

Posted by Mark Gulbrandsen (Member # 72) on 03-17-2004, 09:19 PM:

I'll definately back up what Bob said. In many cases it is possible to do a temporary repair till the normal tech can get there with the proper gear... this probably happens someplace on at least a daily basis.....

In Adams case if it was stereo solor cell it is possible to get it back in there in a temporarily passable condition till the real service tech can get there. I've even done this with the lateral guide roller just cracking the set screw in the middle of the securing nut just loose and then pushing in on the lateral guide to take the pressure off the screw and then unscrewing the nut. This again was just a temporary repair till I could get back and do a proper A chain. In this case the rubber pressure roller had split into several pieces and they could not run..... So a temporary fix it was.

Mark @ CLACO

Posted by Randy Stankey (Member # 64) on 03-17-2004, 09:43 PM:

I wouldn't really want to put grease on the bearings. The reason I mentioned "Oil OR Grease" was because of the possibility that grease, being a heavier lubricant, might passify the problem a bit better than oil would. In a normal situation, like when putting in new bearings, I would definatly use oil. However, in this case, I was imagining that grease might be the leser of two evils. Either you have sticky, squeaky bearings putting friction on the shaft or you settle for a little bit of drag from grease but you can be reasonably assured that the problem won't get worse until you can make the proper repairs.

Right now, the shaft still rotates pretty easily. You can still push the sound drum with your finger and it will still keep spinning about the normal amount of time. But, that squeak is a sure sign of problems on the horizon.

My feeling is that the amount of work it takes to pull the shaft and bearings out dictates that I should only do the job once. If I took it all apart, lubed the bearings and put it all back together again, I'd still have to repeat the task when I got the parts. I think it would be better to do the job once and do it right. I'll just have to keep an eye on it and order the parts as soon as I can pry the money out of the administration.

I guess the main question is to get the manufacturer and part number for a set of "good" bearings instead of the mediocre quality bearings that you usually get.

Posted by Matt Zeiner (Member # 1914) on 03-17-2004, 09:55 PM:

OK. I've never had a problem with greased SH bearings unless the races were damaged to begin with. I get your point, but it has worked for me especially in cases where oil wouldn't alleviate the symptom...

Posted by Darryl Spicer (Member # 711) on 03-17-2004, 11:00 PM:

I have had to pull the sound drum on one of our 5 star soundheads to replace the bearings. All I had to do was dismount the solar cell bracket from the back wall of projector and do the work then remount the cell. Had no sound problems afterwards and the Dolby tone read just fine with no drop out in sound. When our tech was able to come in and check everything nothing needed to be done to that machine.

Randy just tell them how much it will cost to replace the film that gets scratched when the drum locks up.

Posted by Randy Stankey (Member # 64) on 03-23-2004, 09:57 PM:

Just to update things...

I got the bearings replaced today. Wasn't too bad a job. I've done it a few million times. [Wink]

It was the gear-side bearing that was going bad. When I took it out and checked, it felt like it was full of gravel. I got it just in time. It would have frozen up for good if I left it in much longer.

This machine has the Component Engineering reverse scan pick-up in it with the red LED. I took it apart nice and careful like and made sure I got it back together the same way. I ran some Dolby tone and some Buzz Track and everything is just fine. It seems like it's almost exactly the same way as before.

The projector is coming due for its regular preventative maintanence this summer. When I go to do the PM on it I'll rent that scope and RTA and give it a full A-Chain. If I can get a Pink Noise generator for the MOD II-B I might even do a B-Chain! [Smile]

The projector head is used but the sound head was factory new when we got it. We've only put about 2,000 hours on the machine in the last 5 years. These are the original factory installed bearings. I just can't shake the suspicion that there are some quality control issues at play here.

When I get the time I'll snap some pix of the old bearings and post them if y'all want.

Posted by Steve Kraus (Member # 476) on 03-23-2004, 11:25 PM:

Just out of curiousity if you rinsed the bearing out in a solvent and put a few drops of oil in it would it still feel like gravel?

Posted by Randy Stankey (Member # 64) on 03-24-2004, 10:56 AM:

The film-side bearing was fine. I'm going to clean it out, relube it and save it for emergency use. (Whatever use only one bearing would be worth.)

The gear-side bearing is pretty well shot. Not only does it feel like it's full of gravel but the inside moving part has some slop in it. When you push it with your finges you can feel it wiggle a bit.

It still has a LITTLE bit of life left in it but it's well on its way to death. It's a good thing I got it out of there now before it scored the impedance drum shaft... or worse.

Posted by Mark Gulbrandsen (Member # 72) on 03-25-2004, 06:04 PM:

I've always thought that alot of the bearing failure is due to the timming belt shedding and the black particles working the
ir way into the bearings. On the main shaft you can go with bearings that have rubber seals and get excellent bearing life, but not so on the sound drum shaft.

MArk @ CLACO

Posted by Steve Kraus (Member # 476) on 03-25-2004, 08:53 PM:

Maybe there ought to be a little side tap off the Cinefocus to blow the dust away! [Big Grin]

Posted by Mark Gulbrandsen (Member # 72) on 03-25-2004, 11:24 PM:

No need for a turbo particulate blower, just switch to KEVLAR reinforced timming belts as they barely shed anything.

Mark @ CLACO

Posted by Chris Hipp (Member # 1788) on 03-26-2004, 09:44 PM:

I had to replace a bearing today and played around with the old ones a little when I was done.

I dipped it in Chem-tool for about two hours and that got off all of the rust and it spins freely, almost like new. I am sure if I jsut oiled it then I would be able to use it again.

Posted by Steve Guttag (Member # 268) on 03-27-2004, 02:34 AM:

Mark,

I believe you are correct on that Bearing...it is something like a 202 series. The suffix letters can define the shielding. I'm pretty sure we stock two of the three varieties...Full-shield and half-shield. Simplex also used a non-shield variety but those were for the SH-10XX soundheads with the presumption the outer bearing retainer would act like a shield.

Steve

Posted by Scott Manley (Member # 867) on 03-27-2004, 10:14 AM:

Last year due to the only option at a bearing supply place......I used s/h bearings that had a rubber shield on both sides......these seem to last longer than the metal shield ones....only ones I install now.

Posted by John T. Mellor (Member # 468) on 03-29-2004, 02:21 PM:

The bearings with # 6202 is one with no shields, 6202 v one shield 6202 vv both sides shielded change the v to z and its a seal Simplex uses 6201, 6202 quite a lot but they use different part # when it has none , one or two shields . the shields and seals can easily be removed if you need to a shall screw driver will do the job