Guerry Shutter "Refurbishment"

[Steven Tribe]

For Christmas I am getting a couple of Guerry "trap-door" shutters which are the front mounted type. I have been allowed to have a quick look at them and they are shown below. They are designed for 7" and 3" lenses, respectively. They are surprising light 500g and 120g.
Current condition is that one doesn't react to air, whilst the other does - to some extent.
I thought that I would post a series of notes about construction and repair (if possible!) after Christmas. I realise these may not be the commonest of front shutter available but I have a feeling that it may be one of the easiest to steal ideas for own construction projects.
The first thing of note is that the trap doors are just a wire frame with velvet (still light tight) streched across on both sides.

[Steven Tribe]

I couldn't resist loosening the 4 screws and having a look at the innards.
The reason why one wasn't moving is that the expanding rubber bellows has gone (removed)!
The other has hardened so expansion is very limited. Everything else appears to work perfectly and in good condition (hinged wood, tape connection and single spring. Really, really simple compared with focal plane shutters.
Guerry knew the weakness of their product and had glued instructions about the series number of the rubber bellows that should be bought to replace it. So I need a no.4 and no. 8 bellows! Lots of Darlot-like pencil marks, included the date 1903.

I don't think making a rubber bellows will be too difficult!
There is an excellent account of the Guerry and illustrations of front and rear mounting at lungov.com/wagner/c/091c

[Emil Schildt]

I have one in perfect shape.
however I don't use it much, as even as it is very light, the trap door movement is kind of "violent"... And makes the camera/lens shake very easily.

That's why I prefer the barn door shutter made by Norka (and others).

But it is a beautiful thing!!

[Steven Tribe]

The design of the Guerry is very simple and well suited to new home fabrication! The only problem is the folded expanding rubber bellows. I think I have a quick solution based on cycle inner tubes which already have a reliable tube/rubber joint. I am working on it at this moment. Can't understand the vibration problem - must be something wrong under the 4 screws, Emil!
This thread will be continued with "How to make an adjustable (lens diameter) Guerry Shutter" I think.

[Emil Schildt]

Can't understand the vibration problem - must be something wrong under the 4 screws, Emil!
.

hi Steven.
I just think I have been a little stupid...

Just read this article about vintage shutters:

http://randcollins.wordpress.com/2010/08/01/shutters/

they put the shutter at the back of the lens board - not on the front of the lens...

A couple of questions arise though..

1: There are no indications on how to fit the lens on a board...
2: how to make the "T" function work without a lot of trouble...

3: why hide such a beautiful contraption from sight?:o

[Steven Tribe]

The original Guerrys were sold with a slightly larger bulb than usual and a stop valve in the first 10cms of the rubber tubing.
Here are the screws holes where the larger one was was attached to a giant lens board (at least 10x10").
Our visitors are delayed by a dead car battery so I thought I might as well make some images!

[Emil Schildt]

yes - mine looks like the one on the picture drawing. Except for the thingys for electronic flash...

Which, of course makes it impossible to place inside the camera....

Back to square one..

[Steven Tribe]

Easily solved with a very small hole in the front standard, a small cord and a flash terminal.

[Steven Tribe]

More resurrection reporting! I am well aware that this is of specifc interest for only a small minority only - but serve as a stimulus for self construction of simple front shutters for our big barrel lenses.
I have removed the decrepit (but attractive design) actuating bellows from my smaller Guerry. The rubber looks good but is no longer flexible.
I have experimented with cycle inner tubes and they appear to work very well. Butyl rubber doesn't age so rapidly as natural rubber so I expect these to still be flexible in a 100 years.
The cycle tube idea gets around the problem of making a successful seal from the "bellows" to the rubber tube. The inner tube is shortened to a length that fit into the side box when folded double. The ends are sealed with square puncture repair patches using the same glue found in the repair kit.
Next posting will have more photos showing the results.

[Steven Tribe]

And here are more photos.
The clothes peg is used to show how the shortened inner tube will fit when installed. One of the two flat surfaces is glued to the flap which is compressed (like the original bellows). The other is pushed down by a wood distance piece (roughly adusted by a finisher/inspector at Guerry's!) glued to the lid of the mechanism box.
The last photo shows the kind of secure pressure that can be reached in the new "actuating bellows".
Next time will I show the Guerry system in X section drawings.

[Steven Tribe]

X section must wait until another time!
Here is the cycle inner tube "bellows" mounted in position with the connecting rubber tube. The old rubber had to be sandpapered off the brass connector. The cycle tube valve metal was shortened to remove the slots for the internal valve and the external thread was filled up with epoxy to secure air tightness. It works!
Just in case anyone else is doing similar - a few hints! The width of the box containing the "works" does vary quite a lot for the various Guerry sizes. The narrower the cycle tube choosen (racing cycle rather than mountain bike) - the better. Otherwise the expanding tube will foul the long compression spring so that the flap doesn't close light tight.