Recontituting a Unicum shutter

[Ole Tjugen]

Now I have a weird problem...

I have this fine old Unicum shutter, which works perfectly. As a shutter.
But the aperture blades seem to have shrunk! does anyone here have any idea about what I can treat them with, to make them swell to their original size so that the aperture can be adjusted without the end pins coming out of their slots?

See attached pictures - the shutter is fine, but picture 2 shows the shrunken aperture blades.

[Ole Tjugen]

I meant Reconstituting, of course...

[Nathan Potter]

Ole, would it be easier to fabricate a new pin capture plate but with a smaller inner diameter that would retain the aperture pins in their maximum inner radial movement? Using sheet shim stock say laser machined on a CNC mill?

Nate Potter, Austin TX.

[Ole Tjugen]

Perhaps it would Nathan - but I don't have a CNC mill at my disposal.

[cowanw]

I made a larger studio shutter blade out of fully exposed 8X10 film using a good one as to trace and mark holes. Maybe with a scalpel and a dremel drill. Maybe you can make a whole set of the right size.

[Ole Tjugen]

I could make new blades - but fitting the pins would be difficult. Making a new pin capture plate seems like a better option, if I can't find a way to make the old blades swell to their original size.

Searching the net for Unicum shutter information I have found reports that the shutter blades are vulcanite - in my shutter they are definitely steel. But it's possible the aperture blades are vulcanite, but I've failed to find any reports of vulcanite shrinking!

[cdholden]

I'm not aware of any steel alloy having the ability to shrink as much as you're talking about in this shutter. Are you sure this wasn't the victim of some parts pillaging frenzy?
Maybe someone swapped parts with another shutter.

[Jim Jones]

Could the shutter be assembled with the pins in the wrong slots?

[Jim C.]

I tend to agree with cdholden, and Jim, it was probably a victim of a frankensteinian
experiment or it was disassembled for a CLA and wasn't assembled properly, or
worst case scenario the aperture mech is missing a part that would prevent the
leaf pins from falling out.

It may be worth the effort to puzzle them back into their original positions.

[Paul Fitzgerald]

" But it's possible the aperture blades are vulcanite, but I've failed to find any reports of vulcanite shrinking!"

Well you can find plenty of large B&L Unars and Tessar sans iris blades for that very reason. Yes, those plastic blades do shrink and warp fairly often.

You could try paste wax with a Q-tip to clean each blade, the Stoddard solvent in the wax may help them relax back into shape. Any other solvent I can think of would be too strong and may warp them. Maybe butcher-block lemon oil could work.

"It may be worth the effort to puzzle them back into their original positions."

from the photo, they are in their correct position, they 'just short of' pull out normally. The blade have not shrunk very much.

Have fun with it.