Mechanical shutter construction and design?

[adam_frisch]

<p>Is there a pdf or good instructive source on how mechanical shutters are constructed or built? I'm trying to understand exactly how the timing mechanism works on the older type shutters, like Copal etc. I've not been able to find any technical material online except for repair manuals, which don't really helps me understand the mechanisms.<br>

Thank you.</p>

[thirteenthumbs]

<p>At the bottom of the case is an <em>aperture</em> consisting of 5 to 11 blades. The blades close down limiting the size of the opening in a hexagonal, octagonal, or circular pattern depending on the number of blades used. This is used for controlling the light transmitted by the lens.<br>

Above the aperture is the main plate which holds the shutter blades and operator called the blade controller which is mounted on the bottom/back side of the main plate. On the top side of the main plate is the cocking/setting, flash sync, self timer if equipped, and speed delay mechanism.<br>

Upon cocking the shutter the main cocking spring is expanded and locked at full tension. On shutter release the shutter blade controller is moved by a low tension spring opening the shutter blades fully in .0001 to .0003 seconds (1 to 3 milliseconds). The delay timing takes over and prevents the blades from closing for the selected time then the shutter closes.<br>

The flash sync either closes the flash contacts when the shutter blades reach full open which is X or electronic sync or prevents the shutter from opening for 5 to 20 milliseconds depending on the type of flash bulb delay available and selected.</p>

<p>All timing mechanisms used in mechanical shutters use an <em>Escapement </em>https://en.wikipedia.org/wiki/Escapement and gear train similar to mechanical clock movement https://en.wikipedia.org/wiki/Movement_(clockwork) .<br>

Compur shutters employ a coiled torsion spring similar to a clock mainspring to operate the escapement while others use the tension applied by the cocking spring. Self timers also use the main cocking spring tension for the power source to operate. Flash delay mechanisms usually have their own timing spring.</p>

<p>Shutter speeds up to 1/125 second are achieved by reducing the travel of the delay gearing limiting how long it has to run to release the shutter blade controller, once released the main cocking springs forces the blades closed. Speeds above 1/125 second are achieved by adding additional closing force from a booster spring.<br>

Full travel of the delay timer is 1 second.</p>

[tom_chow]

<p>http://www.suaudeau.eu/memo/rep/Compur-shutter-repair-manual.html</p>

[adam_frisch]

<p>Thank you. I had found those before, but they don't really tell me how the timing mechanism works or how timing is achieved.</p>