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Trick to assemble collapsible Summicron aperture?

Discussion in 'Camera Building, Repairs & Modification' started by Helinophoto, Jan 15, 2017.

  1. Helinophoto

    Helinophoto Subscriber

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    Hello

    My lens that I got needed a really good cleaning, so I took it apart completely, lubing up the helical and cleaning everything.

    The blades also needed cleaning (and the aperture ring needed lubing), so I also took that apart.
    - I knew it was going to be a challenge getting it back together but.......what the ...??

    How the heck to get it back together again?

    Is there some tool that the Leica-workers used to get the aperture blades aligned and in position?
    I just cannot seem to get the last 3 blades in, no matter what I do, something slips and it's back to start again.

    Anyone have any experience with this that can give some good pointers as to how assemble?
    Magnets?? Glue?? Some special tool??

    I cannot imagine Leica-factory workers spending 1 week on the aperture back in the day, how the hell did they assemble this thing?
     
    Last edited: Jan 15, 2017
  2. shutterfinger

    shutterfinger Member

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    While I do not have a clue what your aperture looks like or how many blades it has, here is a few things I learned from vintage Compur shutters.
    The blades may have different ends. The pin position, curvature of the blade ends may be different, or hole position different depending on how the aperture is made. The aperture will assemble and work correctly with the blades in one orientation only.
    Assembly is done with the aperture at full open.
    Factories had a jig that they assembled the aperture on.
    If the blade has a pin that goes through the case/frame then put strips of painters tape over the holes on the side opposite the blades then push the blade pin into the tape enough to hold it in place with a light bump.
    Blades go on in a counterclockwise order, starting point should not matter, each blade laying on top of the previous. Once all blades are in then attach the operating ring ensuring each blade engages the mount ring.
    Test by operating the aperture full range.
    No grease or oil should be used on an aperture. Some large format shutters say to use a trace on the aperture plates where they contact the shutter case. Extra fine powdered graphite or dry film teflon can be used on the blades and their pivots.
     
  3. OP
    OP
    Helinophoto

    Helinophoto Subscriber

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    Thanks for the reply.

    The collapsible summicron-aperture consist of 10 banana-shaped blades, one round edge and one flat-edge.

    Here's a photo of a started assembly.
    (better photo is coming)
    :smile:

    The biggest problem is space, there is hardly room to work, its steep and the rear-elements cannot be removed (I think), so rear access to the aperture is not possible.

    2017-01-16 09_07_37-D3S_6414-1200.jpg (JPEG Image, 1200 × 647 pixels).png

    The second issue, is that when I've laid the blades so that the edge of the last blade, meet the first one (and the following ones needs to be put under the first), I've built the blades gradually upwards, so the notch on that last blade isn't flush with the hole, the whole arrangement wobbles at this point, so any touching, will easily create havoc with all the blades.

    Magnets below the lens helps a little, but they are hard to place correctly and they may also put things out of alignment if one is not careful.

    I'm actually contemplating soaking the blades in water, before assembly, the droplets left on the blades will help bind them together.
     
    Last edited: Jan 16, 2017
  4. shutterfinger

    shutterfinger Member

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    The arc shaped blades are standard. 9 to 11 blades provide a circular opening, the number depends on the opening size.
    The rear elements/ group should be removable.
    Post a picture of the rear. The mount ring may have to be removed before the cell can be removed.
    A thread locker similar to clear nail polish was used on cameras and lens. If something is "stuck" saturate the threads or the screw head with nail polish remover and let it sit for 3 to 5 minutes then try it again. I usually dip a cotton swab in the remover then apply to the part rather than pouring the remover onto the part.
     
  5. OP
    OP
    Helinophoto

    Helinophoto Subscriber

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    Ok, I can look more closely on the rear group when I get home.

    From studying the aperture house and rear group though, the only thing I can see, is a small lock-screw about at the middle of the cylinder that house the rear-group glass.
    - But isn't that for for removing the lens-elements in the rear group? As far as I have read, the lenses inside, are seated by friction, so it is not recommendable to try and take them out. (impossible to get in again)

    There doesn't seem to be any other logical/easy way to remove the cylinder itself (unless it is screwed onto the aperture-housing itself from below, or is seated by the small set screw).

    I will try and take some sensible photos when I get home from work, as I know it's no fun trying to help without seeing the actual problem. :smile:
     
  6. shutterfinger

    shutterfinger Member

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    Some lens were crimped in their mount and are not removable per say. I would not attempt to remove a crimped in lens cell.
     
  7. OP
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    Helinophoto

    Helinophoto Subscriber

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    Ok here are some photos of the rear part of the lens, holding the aperture:

    The lens itself with everything in place
    IMG_0039.JPG

    Split from focusing mechanism
    IMG_0040.JPG

    This is the part holding the aperture and rear lens elements
    IMG_0041.JPG

    This looks like a little screw-hole, but I am not sure what for.
    The hole is at 1/3 way to the wop, the aperture is about 2/3 from the top, IE, above the screw-hole.
    IMG_0042.JPG

    Pre-drilled mark/half-hole for the mini-screw, attaching the optical block to the focusing-mechanism.
    IMG_0044.JPG

    Down-view of the aperture itself, it is very narrow when the blades are in there.
    The various markings inside there, is me trying to keep track of where the holes are located during re-assembly. :smile:
    IMG_0046.JPG
     
    Last edited: Jan 16, 2017
  8. shutterfinger

    shutterfinger Member

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    4copy.jpg
     
  9. OP
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    Helinophoto

    Helinophoto Subscriber

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    Hm, I have not tried to unscrew that part, since the area available is so small (also, you can see the glass protruding out the end of that part, one slip and I scratch the rear-element.
    When I look into the lens, I see nothing special, just air. There is a tiny gap between the part you wonder will unscrew and the outer barrel, but I cannot really see anything special.

    I'll leave the lens for a while now, been working on the aperture for about a week without getting it back together again....need a break from it :tongue:
    - Maybe just mount it to the camera and shoot it at f2 for a while, just on spite (the glass is really nice on this one, a little yellowing of the front-group due to the thorium-radiation, but I plan to clear it using a UV-lamp).
     
  10. shutterfinger

    shutterfinger Member

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  11. Marcelo Paniagua

    Marcelo Paniagua Member

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    Would talk from experience here. Really advice you to send it to a tech for reassemble. Got a Summitar lens that I was cleaning. Having done this before with no issues, got careless and just tipped on the lens so it dropped sidewise. Apperture blades just dropped on my workshelf. Tried to assemble them again and it is a mess. Will send it for a total rebuild next week. Sending them along with another Summitar and a rigid summicron pre ASPH and the tech will charge me $240 for the 3 of them, so about $80.00 each. Summitar lens elements are on almos mint condition so it worth CLA's them.

    Wish you luck.

    Marcelo.
     
  12. Marcelo Paniagua

    Marcelo Paniagua Member

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    Wouldn't advise that. Try something that evaporate like alcohol.

    Regards.
     
  13. AgX

    AgX Member

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    The water will evaporate in a stream of warm air.
    BUT any fluid that will run inbetween lens elements will stay there and definitely will necessitate further disassembly. (Been there, done that...)
     
  14. OP
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    Helinophoto

    Helinophoto Subscriber

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    Thanks for your inputs indeed ^^

    I packed away the lens, just to cool my head and let time pass while my brain was working the issue on the back-burner, sort off, and checking the Internet for hints. (very little to find out there, very little and very old information, so the people involved haven't been active online for years).

    As for servicing.....well, where I live, I need to hand the lens over to a "pro photo service", and all they do, is tell everyone that the lens needs to be shipped to Germany, then charge a premium for the service.

    There are very very few people who can service Leica here (privately) and shipping it off to anywhere, will cost a lot in shipping, time and battling the customs and tax-issues.

    Yes, regular vodka should be ok, it's pretty clean and evaporates slow enough it seems. It's a question of having the blades in the spirit and mount them wet (not pour in vodka and use the lens as a shot-glass :D ), this amount should not be enough to soak much, other than the area where the aperture-seating holes are, it also evaporates fairly quickly, so it should be very little risk of it migrating into the lens.

    Also, when looking at the aperture-seating in the lens, it seems to be constructed so that the part with the holes, is actually resting on top of a solid shim. (you cannot see the lens trough the holes for the blades). This prevents light-leaks naturally, but it also protect the lens from any vodka I think.


    Shutterfinger, thanks but I really don't dare to try and remove the rear portion of the lens without reading up on how it it actually attached.....so far I've found diddly-squat on the collapsible Summicron and only a little information on the very similar Summitar.

    As far as I know, the elements themselves are inserted into the back-end and fixed by friction, I have no idea how the back-end tube is actually attached to the aperture-end. Messing too much with that, I am afraid is going to ruin the lens for real :smile: (just too many things telling me "no" about this part of the lens, which is a shame, because it could have given access to the aperture from below).

    However, I did see an interesting video on youtube about maintenance on various lenses, among them, cleaning rusty aperture blades. (here it is, from 16:00 minutes:
    [Play YouTube Video]
    ).

    Now the aperture on that lens is quite different from mine, however, he uses a different technique; He gets the blades in there and then use the (what do you call it?) aperture control cup(?) to hold the blades, while gently pushing the lower blades into the holes.

    I found that very interesting, as the biggest (by far) issue about rebuilding the aperture, is that the blades will come out of the holes if you just look at them hard enough.

    Using the control-cup to keep the blades in check could really work well, as long as at least one blade is actually seated, , the starting point for the rest of the blades should be correct.

    It is very easy to check if blades are seated correctly. By turning the control-cup very slightly (say to f3,5), blades attached properly, will start to move towards the middle, the places not moving, needs to be adjusted "about 5 notches in the counter-clockwise direction", since they are actually supposed to be seated into the hole there. That is also what the guy in this video does. he twists to check operation and adjust any misalignment by locating the notch further down, in the counter-clockwise direction.

    I use a small piece of band-aide patch (the ones you stick onto a small wound) while I work. I cut out the sticky parts and have the (circular cut) felt resting on-top of the lens-element below the aperture. This is very light and it should protect against any falling blades or ill-formed movements with my wooden tooth-picks.

    Looks like I need another tool though, in the video, he use a horizontal, very fine, pick of some kind, it needs to be very very fine (like a dental-tool), and should probably also be secured by a little tape on the bottom-end, to prevent any accidents, should it slip.

    I am doing this in parts, trying various ways 2-3 times, to gauge how hard/easy the process was. Up until now, the closest and "easiest" (less of a hell) I have been to a full rebuild, was using tiny kitchen/hobby magnets, placed around the barrel (held together with tape). I actually only had one blade left to seat, but the last blade ruined the house of cards on that one. :smile:

    I have found that stronger magnets tend to pull on the blades located on the other side of the lens. A few weak ones, seem to work better.

    This isn't impossible, one just has to be careful and find the smartest way to work the problem.
    Like I pondered in my original post, I doubt the factory-workers spent weeks assembling these things, so there simply must exist some other way of cracking this nut, other than fiddling with a house of cards. :smile:

    The biggest problem with the Summicron f2 collapsible, is depth and available space. The narrow passage down to the low-seated blades, makes it all but impossible to insert the last blades, without disturbing the others to a point where they start jumping out of their holes.

    The technique in the video may just solve a lot of issues (while maybe creating others, like trying to locate the misaligned blade with the cup, obscuring the view).
     
    Last edited: Jan 18, 2017
  15. Marcelo Paniagua

    Marcelo Paniagua Member

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    Thanks for the video. Wil look to it tonight.


    Regards

    Marcelo
     
  16. OP
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    Helinophoto

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    Alright!

    I finally cracked this b*tch :smile: :smile:

    Two points:

    1. The blades.
    They go in both ways and since I never saw how the blades were actually seated to begin with, I opted to insert them with the square-end, face down and round-end up.
    They will go in, but this is the wrong orientation.
    When the curve end is showing, the blades can lie way towards the edge of the lens, and it will be very hard to get the notches of the square-end into the holes.
    Here is an example of a mix of right and wrong placements of the blades, as one can see, they go in, either way.
    Note the notches that are showing: On the round-end, they are centered and on the square end, they are slightly off-center.
    When you keep the square end facing UP, it's basically a matter of pushing the blades into the holes, they cannot go way off to the edge and off-center to the hole. (took me a week to notice the difference in the notches and figure that out, so this is a gold-nugget for ya)


    Summicron_coll_blades.jpg

    2. Procedure and tips: Just insert the blades :tongue:
    Using the control-cup to get the final blades into the holes works very well, but you still need to be careful and you still need to get all the blades in.

    Procedure
    * Insert the blades, as shown and explained all over the internet, blade over blade, until you need to start putting the next blades under the first ones.
    - This is fiddly, but use toothpicks (I use one straight and one that I have made into a "L", to lift the first blades). As I insert the final blades, i gently put the "L" toothpick below the existing blade, bend it back slightly and push it gently under the blade, then I let the toothpick rest against the lens-wall.
    - The (first) blades WILL eventually slip on you in the end, but if you are very careful, you will be able to keep at least 7-8 of them in their holes, adjust the rest, carefully, until they are "about so". That means; Align the rest as best you can, so they will fit the aperture control-cup.
    - Careful not to "poke" the blades, you will quickly notice that this tilts the whole arrangement, making other blades pop out of their holes.
    * Insert the "control-cup", or aperture-bucket or whatever it is called. Align it before you drop it (carefully in). Most knobs will enter the grooves in the cup-thing.
    * Use the tooth-picks to gently align any blades not entering the grooves in the cup properly (push and drag the blades below the control-cup while keeping a slight pressure), the cup drops in with a final 'click' when they are all aligned.
    * Do a test-twist of the control-cup to around f3.5, to see how many (if any) of the blades are actually seated, gently (I use a little down-force with my finger when doing this, to prevent any slipping from the cup).
    * Take the cup and blades back to f2.
    * Gently push the edge of any blades showing, towards the edge of the lens/under the control-cup.

    When you do that, you should actually hear the missing blades pop down into their respective holes, as long as you have a slight pressure with your finger.

    I had tried for a week to assemble this thing, with the curved-end of the blades showing. (worst part is, that the aperture will actually work in this configuration, should you ever be able to mount it that way!).
    If nothing else, it really sharpened my fine-mechanical skills (and I have a bunch of new magnifiers too :tongue: ), and the Internet has some new information you cannot google elsewhere, you are very welcome :tongue:

    I made the complete assembly, with the correct alignment of the blades, in about 26 minutes, the lens is now working properly (and I can finally start shooting properly with it) \o/

    I do not fear or dread to do this over again either, as long as the blades are oriented correctly, and the cup is used at the final stage, it's not really difficult.

    - For the record and the internet in the future; This is how I re-assembled/assembled/repaired/fixed my Collapsible Summicron f2 LTM / scew mount aperture.
     
    Last edited: Jan 19, 2017
  17. Marcelo Paniagua

    Marcelo Paniagua Member

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    Nice explanation. Will give it a try to my Summitar, which have a similar (but not equal) configuration next weekend.

    Will post how it went.

    Regards.

    Marcelo
     
  18. OP
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    Helinophoto

    Helinophoto Subscriber

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    Please, only do this if you really really have to, you will eventually also expose the glass inside the lens to scratches, dust and fingerprints, so you need to be absolutely certain that you need to do this before you start.

    Just be very very careful when you remove the aperture-ring and the inner aperture-bucket, make sure you
    - Take photos before each step.
    - Mark the lens, so that you are able to align the cup and the aperture-ring correctly in the end (no fun taking the cup out again to move it to the correct position).
    - Take photos of the original placement and orientation of the blades, even if they fall apart when you lift the bucket out. Very important that they are in the correct orientation before you begin indeed.
     
  19. Marcelo Paniagua

    Marcelo Paniagua Member

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    Thanks for the advise. Will only try it on the lesser (scratched and fogged) Summitar I got. Will send the 2 Summitars and the collapsible Summicron to a tech for proper CLA and blades replacement.

    Regards

    Marcelo
     
  20. OP
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    Helinophoto

    Helinophoto Subscriber

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    Roger that, smart ^^

    Good luck =)
     
  21. shutterfinger

    shutterfinger Member

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    From post #2
    Standard aperture blade design and operation. Compur shutters have aperture blades that are very similar at the ends and if installed incorrectly the aperture will not close down.

    Good to hear you got it figured out and operating. Now when you tackle another one in 5 to 10 years will you scratch your head and ask yourself "how did I do that last time"?
     
  22. OP
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    Helinophoto

    Helinophoto Subscriber

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    Hehe =)

    Welll the strange thing is that the aperture on the cron works both ways, I got 8 blades in the (as I know now) wrong way and tried to turn it, and it seemed to be ay-ok.

    Very deceiving ^^