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Jeff Polaski
Tinkerer
Username: Polaski
Post Number: 1
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 22, 2006 - 07:41 am: | 
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I picked up a Viogtlander 120 folder, with dual format (6x9 and 6x4.5). It has a clean lens (Voigtar 3.5) with a shutter (Commpur-Rapid) that goes up to 1/400, and sounds reasonable when I exercise it. In other words, it's worth working on to get it to user condition.
There is a 6x4.5 mask that slips in, and that has a tab on the lower left that seems like it's the gizmo that tells the camera back that the mask is in place. That means that the correct red window should open when I turn the window knob. Therein lies the rub.
The little metal triangle-shaped tab that is attached to something (quite unseen) under the pressure plate is frozen in place. When I turn the window knob, only one window opens. I see some rust on what might be the pivot for the tab. Gotta be careful here -- what steps (and what materials) should I take to try to free the swivelling tab so that the window selector might work?
(I realize that the spring mechanism under the pressure plate might be trashed already. But, hey, that's Plan B, which is not yet.) |
Glenn Middleton
Tinkerer
Username: Glenn
Post Number: 26
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 22, 2006 - 03:50 pm: |
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I always free up rusted pivots by the careful application of phosphoric or hydrochloric acid. However I have been around/worked with chemicals all my professional life. There are many proprietary rust removers that are suitable; basically the chemical should be water based and have a viscosity similar to water. These products are normally used in dip tanks or for flushing out pipework etc.
Apply the smallest drop to the pivot and leave to react, repeat if necessary. You can neutralise with a spot of bicarb and dry off with a hair dryer. I have always found that this method leaves the assembly completely free, never had to apply any force to 'break' the parts. |
Jeff Polaski
Tinkerer
Username: Polaski
Post Number: 3
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 23, 2006 - 01:16 pm: |
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Thanks, Glenn. I experimented last night with Ronsonol lighter fluid and then DW-40, but carefully applied them with a Que-tip swab. Nothing's moving yet, but it's a lot cleaner. (I experimented first with the gummy camera back opening catch, and it worked like a charm.)
I'm not completely sure that the little nub is actually supposed to move, but I can't see any way that the frame size selection mechanism could work otherwise. I'd love to get a look under the spring mounted pressure plate, but it's rivited on (plate and camera back panel). Friday I'll pick up some rust remover at an old-fashioned hardware store and see what a slow weekend brings. |
Jeff Polaski
Tinkerer
Username: Polaski
Post Number: 4
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 28, 2006 - 10:56 am: |
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No success over the weekend. Got some commercial rust remover from the hardware store (w/rubber gloves): active ingredient seems to be dilute hydrofluric acid. The rust I could reach gets cleaned off. Parts of this camera back are really clean.
But, peeking carefully into the section under the middle of the spring-mounted pressure plate, I see lines of rust between the (hopefully) moveable cams and the back plate of the camera.It looks like the moving parts are "glued" by rust to the flat camera back. Repeated applications don't seem to make a dent.
Worse, the spring that works the mechanism is rusty. It came unhooked as I probed back there. I could probably hook it back into place, but its condition looks bad.
This is pretty much the camera I have (credit to Matt Denton for his writeup).
http://www.mattdentonphoto.com/cameras/v_bessa_69.html
I'm at the point that I think I will not be able to salvage the nifty dual film number window counter feature. Add that to the fact that:
1. the shutter has a little knob up top that seems to lock a cocked shutter, but has been forced over the years and is best left disengaged;
2. the pop-up dual format optical viewfinder cover no longer latches closed (catch on the body missing -- probably a velcro solution here)
and I figure I might have to go to plan B. Plan B would be to detach the pressure plate from the camera back (not likely to be reversable since it uses many rivits), remove the red-window cover mechanism entirely, and remount the pressure plate, sans springs (they are really wobbly), with maybe some 1/4 inch pads of compressible foam at each corner of the pressure plate. Iwould then wind film by remembering which number goes where (you know, the old-fashioned way).
The thing is, I'm really enjoying working on this camera (my first crack at repair), but I am primarily interested in using it as a 6x4.5 format user.
Comments about the insoluble rust-between-2-flat-pieces-of-metal problem, and the foam pad solution would be very, very welcome. |
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