See-Saw Shutters

Does anyone have any practical experience of using a see saw shutter? I am hoping to use the one pictured on my quarter plate Instantograph once the film arrives.
I am guessing that the speed delivered by a full squeeze on the bulb to be around 30th sec. Can anyone bear this out for me I wonder. Also I have worked out that to use the shutter on B you flip over the switch at top left to stop the see-saw arm going through its full travel. But when the exposure time has finished it looks like you have to move this out of the way manually to let the arm complete its travel. There is a possibility of camera movement here or am I missing something obvious?

If you have the "B" lever down to limit upward travel of the piston, then, if the piston and shutter are clean and move freely, you should be able to create suction on the bulb and cause the piston to fall, thus closing the shutter.

So, you would squeeze the bulb, with your finger over the hole on the end of the bulb to open the shutter, keep the bulb squeezed, finger over hole, and
at the end of your exposure release squeeze pressure-still keeping finger over hole-and allow the bulb to reinflate thus causing the piston to drop. This is how it should work for "B" exposures. Remember, don't take your thumb off the hole at end of bulb during the whole exposure and close.

Thank you for your very clear reply; this makes perfect sense.
I think however I still need to do some some more work to completely free up this old shutter. While it is firing well enough it is still a little too sticky to return fully from the open position when using it on B.
Do these come apart (and more importantly) go back together easily for cleaning do you know?

Steve,
The quick answer is that yes, they are easy to disassemble and put together for as long as you keep track of what goes where. The real trick to getting the most efficiency from this particular shutter design (air-piston regulated) is to make sure that the inner surfaces of the cylinder and the outer surfaces of the piston are impeccably clean. Having said that, you should also continue to expect a certain degree of variability in the actual speed possible from the mechanical arrangement. Clean and lubricate with the thinnest oil available to you all critical pivot points. Do not under any circumstance lubricate the piston and the cylinder walls. They should be as dry as possible.

dmax said:

The real trick to getting the most efficiency from this particular shutter design (air-piston regulated) is to make sure that the inner surfaces of the cylinder and the outer surfaces of the piston are impeccably clean. Having said that, you should also continue to expect a certain degree of variability in the actual speed possible from the mechanical arrangement. Clean and lubricate with the thinnest oil available to you all critical pivot points. Do not under any circumstance lubricate the piston and the cylinder walls. They should be as dry as possible.

Click to expand...

I think you have it here. The piston and cylinder walls did have some gummed up greasy stuff on them when I received this shutter and while I thought I had removed enough of it to make the shutter workable, obviously I have not. I shall revisit my cleaning efforts.

Steve,
The best cleaning liquid for these things is lighter fluid (naptha). If necessary, soak the cylinder and the piston, and then clean the insides of the cylinder. If you have some metal polish, polish the piston to eliminate minute galling and surface imperfections. Then wipe it clean with some naptha prior to re-installation. I hope this helps.