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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » 3D Wheel vibration is making too much noise

   
Author Topic: 3D Wheel vibration is making too much noise
Michael Jamieson
Film Handler

Posts: 4
From: Sandwick, Shetland, UK
Registered: Mar 2018


 - posted 03-03-2018 10:29 AM      Profile for Michael Jamieson   Email Michael Jamieson   Send New Private Message       Edit/Delete Post 
Hiya, our setup contains a MasterImage 3D system, with a motorised rail which automatically slides the 3D wheel in front of the projector for 3D shows. The rail and wheel are mounted directly to the concrete wall in the projection room, and there's a lot of vibration noise, which manifests itself as a low frequency hum, which goes on in the background for the entire film show. Very noticeable in the cinema, especially at quiet moments in the film. My question - has anyone experienced a similar problem, and is there a way to mount the rail and wheel with something which will absorb the vibration?

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Dave Macaulay
Film God

Posts: 2080
From: Toronto, Canada
Registered: Apr 2001


 - posted 03-03-2018 02:07 PM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
I haven't seen one mounted to a booth wall. Most MI wheel systems are movable floor units with the 2D/3D movement vertical. We have one horizontal movement one in a ceiling box, it sits on rubber pads and is pretty quiet - sitting near the box you can tell if it's running but it is not annoying.
There are vibration isolators for such applications but it will be simpler and easier to make a stand that sits on the floor for the assembly to bolt to.
And this probably belongs in "digital", I don't think MI made a film 3D system?

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16111
From: Bountiful, Utah
Registered: Jun 99


 - posted 03-03-2018 10:39 PM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
Carefully check the disk, it is out of balance for some reason or other. Replace it if you can't figure it out. I've had the early disks explode and do considerable damage to the lens and booth personnel, and although the current ones don't do that it still may if it gets far enough out of balance.

Mark

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Carsten Kurz
Film God

Posts: 3680
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 03-04-2018 07:39 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
Since RealD did a 'unfriendly takeover' of Masterimage, their original products and webite diappeared. Is RealD still providing replacement parts/discs for Masterimage systems?

I have never seen a wallmounted spinning disc system either. Can you supply a photo? Google doesn't seem to have one.

- Carsten

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16111
From: Bountiful, Utah
Registered: Jun 99


 - posted 03-04-2018 12:02 PM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
All the Masters I installed were floor standing spinning disks. Some of the last stuff they produced like the Wave was quite good. And it did not utilize a spinning disk.

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Phil Ranucci
Expert Film Handler

Posts: 227
From: Carpinteria,CA, United States
Registered: May 2006


 - posted 03-05-2018 02:37 PM      Profile for Phil Ranucci   Email Phil Ranucci   Send New Private Message       Edit/Delete Post 
If you have a spare disc swap it out. We had one that a booth person sprayed with alcohol to clean. The glue holding the plastic layer on the disc dissolved and cause an amazing amount of noise.
Anybody know if discs will be available in the future?

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Randy Stankey
Film God

Posts: 6410
From: Erie, Pennsylvania
Registered: Jun 99


 - posted 03-05-2018 03:05 PM      Profile for Randy Stankey   Email Randy Stankey   Send New Private Message       Edit/Delete Post 
I don't know the specifics but I can tell you that any rapidly spinning machine/device that was once quiet but suddenly starts to vibrate and make noise has a problem that needs to be resolved post-haste. Left unsolved, this problem will likely result in an "Unplanned Rapid Disassembly," the aftermath of which will not be pretty. Anybody in the vicinity of such an accident will get hurt by flying shrapnel.

Check the disk for anything that could throw it out of perfect balance such as chips, cracks and any other damage or dirt.

Check the shaft to be sure that it is straight and true.

Be sure that there are no rotating parts that are touching anything else that they aren't supposed to be touching.

Check bearings, motors, gears, belts or other linkages to be sure that they rotate/move freely, the way that they are supposed to and are not worn, frayed or otherwise unsound.

I'm sure that you've seen enough fans, rotors, grinding disks, saw blades and other such things which have come apart while in motion and I don't think that I have to tell you that it is not pretty.

You wouldn't want that system to "rapidly disassemble" on s Saturday night with a house full of customers. Would you?

Please shut it down until you can get somebody to look at it.

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Michael Jamieson
Film Handler

Posts: 4
From: Sandwick, Shetland, UK
Registered: Mar 2018


 - posted 03-09-2018 05:50 AM      Profile for Michael Jamieson   Email Michael Jamieson   Send New Private Message       Edit/Delete Post 
Hi guys, thanks for the replies, I appreciate it. It hasn't just started to vibrate, it's always vibrated, since it was installed. It's had a change of disc too. It's definitely the fact it's bolted straight to the wall with no isolation. We're not really able to move it and mount it seperately, as it sits in a 300mm gap between the wall and our server racks (which we can't move). We could probably move it out from the wall by about 50mm, but I'm needing a vibration absorbing mount of some kind. Anyone seen such a thing?

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Carsten Kurz
Film God

Posts: 3680
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 03-09-2018 07:38 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
There are disc, or 'puck' type rubber shock absorbers with either threads or screws on both sides. Without having seen a picture of your installation, it's hard to judge wether they are applicable, but that would be the first that comes on my mind for this. The larger ones should be strong enough to hold an MI.

Here is an example: https://goo.gl/images/B8GUk5

Google/ebay/amazon for 'rubber shock absorber' !

Using just a rubber piece with a through-screw wouldn't help much, but these absorbers have no hard connects between either sides.

- Carsten

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Dave Macaulay
Film God

Posts: 2080
From: Toronto, Canada
Registered: Apr 2001


 - posted 03-09-2018 07:48 AM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
Yes. There are thousands of different ones. Search "vibration mounts".
The designs tend to get very specific - mounting angle, device weight, frequencies to be isolated, etc. But pretty much whatever you can find - any type designed for wall mount use and for the MI weight - should be OK.
Here in Canada there are places like Princess Auto with an assortment to pick through.
This will naturally allow more vibratory movement in the mounted MI unit - if the isolated assembly resonates at the wheel RPM frequency... it may shake itself apart.

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Michael Jamieson
Film Handler

Posts: 4
From: Sandwick, Shetland, UK
Registered: Mar 2018


 - posted 03-13-2018 02:52 AM      Profile for Michael Jamieson   Email Michael Jamieson   Send New Private Message       Edit/Delete Post 
That's excellent, thanks guys

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Randy Stankey
Film God

Posts: 6410
From: Erie, Pennsylvania
Registered: Jun 99


 - posted 03-13-2018 01:59 PM      Profile for Randy Stankey   Email Randy Stankey   Send New Private Message       Edit/Delete Post 
quote: Dave Macaulay
if the isolated assembly resonates at the wheel RPM frequency... it may shake itself apart.
I was just thinking about that, too.

If you could create a shock mount where the machine is mounted to a metal plate or bracket which is, in turn, mounted to the wall with two sets of vibration dampeners of slightly different stiffness it might prevent that.

In other words, create something like a compound pendulum that never gets into a steady state.

Two problems with that idea, though:

First, it would take some experimentation with different stiffnesses, etc., etc., to get something that works right.

Second, we've only got about two inches of space to work in.

Time to fiddle and space to play in are not luxuries we have.

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Michael Jamieson
Film Handler

Posts: 4
From: Sandwick, Shetland, UK
Registered: Mar 2018


 - posted 03-16-2018 08:54 AM      Profile for Michael Jamieson   Email Michael Jamieson   Send New Private Message       Edit/Delete Post 
Nice idea

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