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» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Polishing the sound drum (Page 3)

 
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Author Topic: Polishing the sound drum
Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000


 - posted 08-15-2001 12:36 AM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Gordon, as far as Dash Pots are concerned, the Ballentyne Mod 7 must have been the worst in the industry. Any comments?

P.S. - your screening room with the Moshees is a real beauty! I would love to run a booth like that. You must have spent alot of time and money on that project. Job well done.

Paul


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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99


 - posted 08-15-2001 09:21 AM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
Actually the older Model 7's with the rotary dashpot was quite good and didn't wear out. They cheapened it up though and use basically the same one Christie uses. In both of these cases it really does nothing at all.
As far as the finish of the drum surface is concerned I hvae found that it really does not matter much. It may take a little longer to reach speed but they still work fine. I can't remember what grit of wheel the shop that did mine used so I can't speak in terms of actual surface finish here. Perhaps someone at Strong can clarify this a bit.
Mark
Mark @ GTS


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Gordon McLeod
Film God

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


 - posted 08-15-2001 10:00 AM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
Actually EPRAD had the best finish on a sound drum a in effect a PTR roller
Paul those AAA have a bit of history they were installed new in the MGM screening room in toronto and were used until the early 70's when they went to a local indi. When they replaced them with a platter and a Vic5 I bought them. They wouldn't sell the penthouses and magazines though so I tracked down a pair of motiograph mags and penthouses in detroit.
The mag preamps were a magnaphonic tube system and the power amps were all AMPEX with for a long while a RGM then a SUperStarscope and finally a CP100 At the back of the room not visable is 3 Amega dubbers locked to each machine

Soon it will get renovated to a pair of 35/70 with a 200 when time permits

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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000


 - posted 08-15-2001 12:44 PM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Mark, there is a possibility that the reason why I was told this was because if they polished themselves so bright through years of service, the scanner drums might take a goofy wear pattern and run askew. It makes sense to me. And, I agree about the idea they might slip a little more on start-up than usual, and since that is on the leader, it is no real big deal. It is all equalized proir to changeover, unless the bearings feel like someone poured poly-grip into them.

Personally, I never really cared for the cushion (impedance) rollers. I have seen some of them build up so much crud that the crud was hammered into the emulsion side of the film. They bounced, and just literally ran funky. The felt rollers were a disaster for that.

The squirrely rubber rollers were not much better. Even if those were kept clean, you could still see railroad track smudges on the emulsion side of the film after many runs of the print.

The solid rubber ones seemed to fare much better. All they left was a BIG WIDE railroad track.

Unfortunately, operators forget to clean the rollers and guide flanges on a regular basis.

Some of those scanner drums get really bad! Even Buzz-Track was all over the place...especially if the guide flanges and the scanner shaft bearings were less than perfect.

The scanner drum Josh and I did looked good when we finished. It was almost a basket case when we started, but now it has has a smooth (but not glossy) machined looking surface. I think it will be OK. It still had some small rust specks in it, but those will polish out eventually. I have seen some in service that look much worse that what he has now.

I forgot to take my micrometer and a run-out indicator with me, so I could not check it for "wooga wooga's" or other defects. It was a "fly-by-the-seat-of-the-pants" type of repair.

If for some reason it is out-of-round, there is a good machine shop in his area that could square it up for him without too much trouble. The only thing he might have to re-do is the sound focus.

Paul


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