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repair

 
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geneaker



Joined: 05 Feb 2008
Posts: 5
Location: santa fe, new mexico

PostPosted: Sat Oct 09, 2010 10:24 pm    Post subject: repair Reply with quote

Alas. The lens on my super speed graflex is jammed. The lens is the Rodenstock Optar 4.7 Graflex. It;s the one with the twist-to-cock barrel. The lever on the lensboard for moving the blades to open for focusing has gotten very stiff and will not open the blades fully. I do not want to force it.
The shutter operates perfectly. I love this lens on the Super Speed and would hate to retire it! Is there anyone who can fix it?
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45PSS



Joined: 28 Sep 2001
Posts: 3233
Location: Mid Peninsula, Ca.

PostPosted: Sat Oct 09, 2010 10:30 pm    Post subject: Reply with quote

email sent


for the benefit of future readers:
Conventional shutters such as Wollensak Betax, Ilex/Acme, Synchro-Compur, Kodak Supermatic, and similar shutters, the shutter blades are attached to a pivot pin and are operated by a cam with a pin in a slot in the blade. The cam is controlled by spring tension and a gear train. When the lubrication dries out the gear train slows causing the shutter to slow down resulting in incorrect exposures.

The Graphic 1000 shutter has an gear driven eccentric for each shutter blade. The shutter blade eccentric gears are driven by a main drive gear. There are 3 speed gear trains that regulate the master drive gear and a synchronizer gear train. When lubrication dries out the eccentric gears and the main dive gear become difficult to move resulting in increased difficulty to cock the shutter. The drive train will continue to operate at correct speed until the drag on the eccentric gears becomes so great that they no longer move or they strip. If an eccentric gear strips that shutter blade will not be in correct position and leave a gap in the blade pattern in the closed position and most likely leak light.
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Last edited by 45PSS on Sat Oct 30, 2010 3:46 am; edited 1 time in total
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pv17vv



Joined: 22 Dec 2001
Posts: 255
Location: The Ardennes, Belgium

PostPosted: Sun Oct 10, 2010 6:13 am    Post subject: Reply with quote

Thanks Charles, the explanation is crystal clear.

Quote:
the twist-to-cock barrel.


???

Someone please explain what this is, I've never seen a Super outside the www and there seems to be no description of this mechanism (at least where I've searched).
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45PSS



Joined: 28 Sep 2001
Posts: 3233
Location: Mid Peninsula, Ca.

PostPosted: Sun Oct 10, 2010 7:19 am    Post subject: Reply with quote

Standard shutters are cocked by a lever that increases spring tension on the cam plate spring so that when the trip lever is pressed the spring tension is released as the cam plate moves operating the shutter leaves.

The Graphic 1000 shutter main drive gear is spring loaded and cocked by turning the gear. The mechanism forms a series 6 filter retainer and lens hood that is turned clockwise to cock the shutter. The drive gear works similar to a ratchet allowing the drive force to be applied in one direction only. When cocked the spring tension on the main drive gear is increased. The speed ring selects which of the 3 speed gear trains controls the release of the spring tension when the shutter is tripped.

Conventional wisdom says the Graphic 1000 shutter is flawed and to junk it on failure. Because it operates differently conventional wisdom does not apply and anyone waiting for the speeds to become slow before seeking service wind up with a shutter that is jammed or has a striped eccentric gear.

Anyone with a high level of technical ability can get a service manual from Craig Camera and Clean Lube and Adjust this shutter.
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