Betax #4--hard to repair?
I finally won an auction for a 12 inch lens for my 8x10. Had to do it the poor-man's way, like everything in my life. It's a Bausch and Lomb in a Betax #4. The ad said the shutter "used to work, but doesn't now". So it looks like I'm going to have to do either the naptha trick or the alcohol trick, depending on what the shutter blades are made of. And if that doesn't work, I'll have to open it up. I never worked on one of these. Rather than asking for detailed advice, should I expect things to go flying through the air upon opening it? Where is the access point to the interior of the shutter? I might mention that it looks like there's no retaining ring. So that means I'll have to carefully file my homemade wooden lensboard (which doesn't exist yet), so the shutter is jammed in the hole and put a bead of hot glue around the threads. Not having a retaining ring is disappointing, but not earth-shattering. Thanks.
From memory (and it's been a while....) they are easy to fix. Being so large there is lots of space to work, and from memory (well either the #4 or #5) has the shutter blades screwed in to the backing plate, so when oyu dismantle it things don't fall out when you least expect it....
I found these pics on the web - they should help you...
Now here's something really crazy. I just went way down deep into this shutter. To the point that shutter leaves are coming off their pins and fell out. I've got a picture of how they go, so that much I'm happy enough about. But I've got a leaf leftover. There are 5 pins, and the picture of the shutter I'm looking at on the web has 5 leaves. So why do I now have a 6th one leffover? BTW. Somebody has been into this thing before. The original problem was that the mechanism and timer worked OK but the shutter wasn't opening. Where in the world did this 6th shutter leaf come from? There's no place to put it back in. All the pins are taken. Strange.
I don't know about that model of shutter, but I would try putting it on top of the first leaf put in. In other words, say you are putting the leafs on in a clockwise manner. After putting the 5th one in, put the 6th on top of the first one you put in. Hope this helps.
That's what I thought too, and it seems to work. I'm beginning to think this whole shutter needs a good powdering of graphite the way it's designed.
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also check if there is a slight bend to any of the tips (the pointy ends) of the shutter blades - if there are the first one you pt on should point down, and the last one point up.
otherwise yes - the 6th is a capping blade and goes above where the first one went
The blades seem to be made out of plastic. I thought about that too, but I'm not sure plastic can keep any kind of meaningful bend. Plastic in 1912, I doubt it, but they sure don't seem to be metal. I,ve got that much of it back together, but I'll take it back apart tomorrow because it looks like 2 blades could be shifted to make the stack a little tighter.. As I hold it up to the light I can see a little light leaking around when I turn the assembly to a sharp angle to the light bulb. I only originally had 3 of the six blades fall out and get mixed up. I suppouse I was bound to disassemble the shutter more than I really needed to, but sometimes you have to do that before you understand.
Another thing. I looks like the actual timing mechanism does not have any viable way to correct the timing. Looks like a simplified Nikon F self-timer mechanism. Just no adjustment. Looks like the only real way to know what shutter speeds are is to buy a cheapo EBAY shutter-speed tester, and mark the dial according to that. I'm also amazed this shutter has no setting for 1 second. They give you 2, 5, 10, 25, 50 T and B, and that's it.
Well, lets continue on for the edification of future internet searchers. I've disassembled this shutter completely. I had to--the aperture blades had slipped out of their sockets after the solvent treatment. I discovered a past worker had likewise disassembled the aperture pivot plate and had bent a couple of the aperture blades slightly. I had the dickens of a time putting the upper pivot-slot plate back in proper position such that the aperture assembly could move full travel. After finishing, it has a tendency to jam and want to cause the blade pivots to slip under and past their slots.
Oiling does help, but not a lot--the blade pivots still want to slip underneath the slot-plate and jam the mechanism. And this is where I have reached a conclusion regarding lubrication. Lubrication MUST be used on this mechanism, but I think it should be graphite, not oil. I believe graphite should be allowed to migrate on the aperture blade surfaces, further reducing the binding problem which causes the aperture-blade pivots to slip underneath and past their slots, causing jamming, bending, and probable breakage of aperture blades. I'm going to soak it in naptha to remove any oil I applied tonight and go buy some graphite tomorrow. The design of this shutter inherently causes oil to migrate out onto the aperture blade surfaces. This is bad. If graphite migrates, it seems that would actually be for the better.
All you need for shutter CLA:
extra fine powdered graphite http://www.agscompany.com/lubricants/homehardware/183
light weight oil http://www.triflowlubricants.com/Tri...Lubricant.html
white lithium grease http://www.amazon.com/Permatex-80345.../dp/B000HBNV58
degreaser that leaves no residue and is safe to use on rubber and plastics http://www.amazon.com/CRC-Electrical.../dp/B003NTQCA2
3in1 oil is vegetable base and will dry out quickly and leave a sticky residue.
Water Disperant 40 contains a light weight vegetable based oil and leaves a sticky residue.
Lighter fluid leaves an oily residue.
Naphtha will damage plastic and rubber components used in shutters made form the 1940's and newer.
I rub the graphite into the aperture and shutter blades and their pivot pins with a q tip then remove any cotton fibers.
The #1 shutter blade has a special pin for the #6 capping blade, it will be different from the other blades.
Shutter speed testing, the last posts are the most up to date. I put a piece of dark red lighting gel equivalent to a #25 red filter over the sensor and use a 2 AA cell mini mag set to spot at 2 inches for tests.
Shutter blade starting point is adjacent to the release lever and goes clockwise as viewed from the front of the shutter. The photo below is inaccurate, I am unable to delete it. The correct on is above.
Last edited by shutterfinger; 08-06-2013 at 02:15 AM. Click to view previous post history.