8mm Forum: Noisy Eumig Mark S 712D

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Posted by Will Trenfield (Member # 5321) on April 14, 2018, 06:36 PM:

This projector, like other sound projector models in the Eumig range, uses a clutch system rather than a drive belt. A ball mounted on the drive shaft from the motor sits between two rubber coated disks. This engages with the front disk for forward motion and the rear one for reverse. There's a lever to select speeds of 18 fps or 24 fps. This causes the ball on the end of the drive shaft to make contact with the outer or inner sections of the rubber disk which changes the speed. At 18 fps, the projector runs fairly quietly but, at 24 fps, it's noisy and almost drowns out the sound track. Can anyone explain why this should be happening, please?

Posted by John Last (Member # 3414) on April 15, 2018, 09:52 AM:

Hello Will from Codsall! I have one of these and I guess that the lower motor bearing may be dry. To lubricate this, remove the back plate. Cut a piece of cardboard 10cm long by 1cm wide and fold it in half long ways. Put a few drops of 3 in 1 oil on one end of the cardboard and feed it into the narrow gap between the lower motor bearing and the fixed portion. Leave to stand on its side for a minute or two and then try the projector. If it's still noisy, oil all of the round bearings on the long horizontal shaft. Then if the trouble is still there look to the cam on the shutter mechanism and grease this with a smear of molybdenum disulfide grease. Best of luck, John

Posted by Will Trenfield (Member # 5321) on April 15, 2018, 04:00 PM:

Thanks for that, John. I've done as you suggested. Although the projector seems to run more smoothly, it's still very noisy at 24 fps. At 18 fps it's fine. When the drive is engaged, it takes a few seconds to get up to full speed and then comes the noise. Changing the speed only moves the drive to the inner part of the rubber disk and doesn't affect anything else so I'm stumped. I can always listen on headphones, I suppose.

Posted by Zechariah Sporre (Member # 2358) on April 15, 2018, 04:15 PM:

Hi will. I once had a Eumig that apparently they let the motor run for a while in forward while it was slipping on the rubber disc and it made a dimple in the rubber so it made vibrating noise at 24fps in forward. Is that the type of noise it makes? Does it make the same noise in reverse as well?

Posted by Will Trenfield (Member # 5321) on April 15, 2018, 04:55 PM:

Thanks for your posting, Zechariah. Yes, it makes the same loud mechanical noise in reverse as well. The rubber disks have been cleaned with isopropyl alcohol and look fine. It seems to me that the noise is coming from the shutter area but I can't figure out why the speed should affect that. Sound films at 24 fps project fine.

Posted by Steve Klare (Member # 12) on April 15, 2018, 09:45 PM:

Just a thought, Will...

The centrifugal forces on the blades go up with the square of the rotational speed (frame rate).

Just maybe you have a blade that's slightly twisted and the extra forces between 18 and 24 FPS (almost double) are dragging a blade tip against some surface inside the machine.

Maybe I've taken too much Physics, but it just sounds plausible.

So try running the machine and look for wiggling blades?

[ April 16, 2018, 08:33 AM: Message edited by: Steve Klare ]

Posted by Will Trenfield (Member # 5321) on April 16, 2018, 01:15 PM:

A bent blade is certainly a possibility, Steve, although they all look alright. I'll get my feeler gauges out and check clearances. The projector is nearly 50 years and is a bit battered probably due to it having had a few owners. I bought it from a guy on eBay for £5.50 plus shipping and he'd only purchased it to digitise some silent family films. Thanks.

Posted by Steve Klare (Member # 12) on April 16, 2018, 03:50 PM:

There has to be some sort of bearing up there as well. Sometimes they need to exceed a certain speed before they get noisy.

Posted by Will Trenfield (Member # 5321) on April 16, 2018, 05:10 PM:

The blades are ok so it could be a bearing as you say, Steve. There are 3 on the drive shaft, I think. The noise, which is reminiscent of a motor bike, seems to come from towards the front of the machine where there's a bearing. Needless to say, it is the most awkward one to reach.

Posted by Simon Wyss (Member # 1569) on April 17, 2018, 01:54 AM:

Probably the motor mount. Motor has two studs that sit in synthetic rubber trapezoïdal bearings. Those may be deteriorating. The plain bearings inside are not accessible. I have had a mechanic replace them by ball bearings but he had to machine out space for that. Once you have the motor bearings and its mounts made right, the main shaft needs a drop of oil in the bearings from time to time. All in all a cold-war cybernetics blockhead design of a projector, a throw-away product. Pity

Posted by Stuart Hilliker (Member # 737) on April 17, 2018, 04:37 AM:

Hi Will.
I had a similar problem with a Eumig projector. I replaced the motor mounts with these:
https://shop.van-eck.net/PP-0138.html

It certainly did the trick.

Posted by Will Trenfield (Member # 5321) on April 17, 2018, 01:20 PM:

Thanks, Simon and Stuart. Yes, the material holding the motor mount bearings can break up with age. The feet were made from the same stuff and I've seen some missing or broken. Luckily, the motor mount I can see is fine so I'm hoping the hidden one is the same. There's no play to suggest otherwise.

Posted by Will Trenfield (Member # 5321) on April 18, 2018, 04:32 PM:

I seem to have fixed it thanks to the advice given on this thread. The drive shaft is supported on three bearings which partially sit on cups cast into the projector body. A steel plate holds each in place. The front bearing is hard to reach due to the mains socket mounted on the transformer being in the way. I unscrewed the transformer and was able to move it an inch or two out of the way so that I could unscrew the plate holding the bearing in place. There was enough play for me to slide the bearing along the shaft so that I could apply lithium grease. It's running far more quietly now at 24 fps. Thanks to you all for your postings.

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