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Thread: Cleaning of slow shutters

  1. #21

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    Re: Cleaning of slow shutters

    Quote Originally Posted by Pete Oakley View Post
    The advice about storing shutters uncocked and set to T (preferably) or on B if T is not an option was posted on this site several years ago by Carol from Flutots, if you don't want to take Carols advice..........get on with it!
    Pete.
    I've always stored all of my cameras/shutters -- of any format -- uncocked. I've never heard of the "T or B" idea. Why would that make a difference? I would imagine that there is no "tension" unless the shutter is cocked. This "B/T" notion sounds like yet another photographic myth, up there with the idea that higher silver content in papers produce blacker blacks.
    Last edited by xkaes; 26-Dec-2017 at 06:41.

  2. #22
    8x10, 5x7, 4x5, et al Leigh's Avatar
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    Re: Cleaning of slow shutters

    Quote Originally Posted by Mark Sawyer View Post
    Pocket watches are designed to run perpetually, days of continuous use per winding, one winding after another. Shutters are designed to slam relatively large shutter blades open and shut for fractions of a second, occasionally. Different mechanisms altogether.
    Irrelevant.

    Your earlier comment, to which I replied, stated that springs degrade with time/use.

    That is not true.

    - Leigh
    If you believe you can, or you believe you can't... you're right.

  3. #23
    Dave Karp
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    Re: Cleaning of slow shutters

    Quote Originally Posted by Pete Oakley View Post
    The advice about storing shutters uncocked and set to T (preferably) or on B if T is not an option was posted on this site several years ago by Carol from Flutots, if you don't want to take Carols advice..........get on with it!
    Pete.
    I don't know why she makes this recommendation. I know that she knows more about shutters than I do, so I follow her advice and don't lose any sleep about it. I don't see how it could hurt.

  4. #24

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    Re: Cleaning of slow shutters

    Quote Originally Posted by David Karp View Post
    I don't know why she makes this recommendation...
    If a shutter if well engineered you can store it cocked or with 1/125 speed set.

    Anyway "Carol from Flutots" gives a good recommendation to avoid problems, in special with old shutters.

    The reason is the "permanent set" an spring may have if loaded permanently, it can happen that the spring keeps a permanent deformation, so it will retain less energy/force because that. It has to be noted that this is not to happen if the spring is well designed, with the right steel and dimensions for the job, that would make "permanent set" level irrelevant.

    An example are mechanical clocks, having several springs that are properly designed to not have problems of permanent set or fatigue breakdown.

    ...but as we don't know what shutter models are prone to have that problem, better always store all in those (for sure) safe conditions, IMHO.

  5. #25
    Pete Oakley
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    Re: Cleaning of slow shutters

    Leigh, I might have misunderstood you but springs do degrade with use. Many, many years ago I was trained as a clock maker and if springs don't degrade with use why do / did suppliers to the trade sell new springs? I don't know the source of your information but it's wrong. I have replaced many clock mainsprings, through necessity.
    Pete.

  6. #26

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    Re: Cleaning of slow shutters

    Quote Originally Posted by Pete Oakley View Post
    Leigh, I might have misunderstood you but springs do degrade with use. Many, many years ago I was trained as a clock maker and if springs don't degrade with use why do / did suppliers to the trade sell new springs? I don't know the source of your information but it's wrong. I have replaced many clock mainsprings, through necessity.
    Pete.
    An spring well designed for a job do not degradate, but it can have a manufacturing defect that will end with breakdown after a lot of cycles.

    If a very small surface crack is present it can grow with cycles, as there is an stress concentration factor in the inner end of the crack. Polishing exposed surfaces improves a design because you get rid of surface cracks that would start cracking sooner if the design is to have fatigue. When the crack is big enough then the part is broken because ultimate tensile stress limit.

    https://en.wikipedia.org/wiki/Fatigue_(material)

    One can design an spring to resist an "infinite" amount of cycles (if no severe manufacturing defect), or one may calculate the part to have say a 10% risk of breakdown after say 10 million cycles...

    Also a well designed business may get 30% of the profit from spare parts.

  7. #27

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    Re: Cleaning of slow shutters

    Quote Originally Posted by Pere Casals View Post
    Also a well designed business may get 30% of the profit from spare parts.
    Such cynicism, in one so young!

    For what it's worth; I agree with general theory that springs don't 'wear out' though if improperly designed or manufactured for the job they may fail in use. I wonder though, how much effect on the bearing points occurs due to the load from a spring on the pivot point?

    Neil

    p.s. in the company where I work, we try very hard never to need to supply spares (in fact, we don't have a spares programme; we generally supply a new or repaired unit). Spares are a pain to manage.

  8. #28

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    Re: Cleaning of slow shutters

    Quote Originally Posted by barnacle View Post
    I wonder though, how much effect on the bearing points occurs due to the load from a spring on the pivot point?

    IMHO again, only a very poor design would provocate a permanent deformation in the shaft or the bore from a permanet load and no movement, wear has to come from friction, and it is way more important if no lubrication. Here we can remember the interesting Tourbillon mechanism (Breguet clockworks) where the bore also rotates to have a uniform wear that conserves clock precission (https://en.wikipedia.org/wiki/Tourbillon).

    If the bore wears quickly to a not circular shape this would be because working with lack of lube, IMHO, as the shaft may be loaded with a radial force, in clocks can be just gravity, but of course that directional force can come from mechanism action, as in the gears case, where we have an equivalent radial force of constant direction plus a torque coming from force in the teeth.




    Quote Originally Posted by barnacle View Post
    p.s. in the company where I work, we try very hard never to need to supply spares (in fact, we don't have a spares programme; we generally supply a new or repaired unit). Spares are a pain to manage.
    Of course, and this will depend on product and manufacturer policy, but for sure a lot of products rely on parts and consumables.

    In the car industry we have timing belts instead timing chains. This allows the car seller to get an income that in practice is (partially) discounted from his margin in the sell, so the seller will get the profit from expanded servicing costs.

    In the consumables realm we have the infame ink business for printers. We are lured by a low printer cost but charged $15 for 4ml, this is $3750 per liter, while the 1L ink cost may be lower than $10.

    Also we have pre-programmed product autodestruction, this came with incandescent bulbs, but also it can come with refrigerators or cars, for the cars the 2nd owner should have increased service costs, and the car has to blow up soon in the hands of the 3rd owner, this would be a perfect business. Brands may be more or less prone to that, but today they have another tool for that, electronics and LCD screens onboard.

    In the DSLR realm cameras don't fail much, but there is a programmed obsolescence.
    Last edited by Pere Casals; 26-Dec-2017 at 05:31.

  9. #29
    Mark Sawyer's Avatar
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    Re: Cleaning of slow shutters

    Quote Originally Posted by Leigh View Post
    Irrelevant.

    Your earlier comment, to which I replied, stated that springs degrade with time/use.

    That is not true.

    - Leigh
    Quoting my comment, "If you store the shutter at a timed speed, there is tension on the spring that drives the shutter, and the higher the speed, the greater the tension. Over time, this will reduce the "springiness" of the spring, making it weaker, and the shutter more sluggish."

    It's tension over long periods of time that does the damage.
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  10. #30
    Mark Sawyer's Avatar
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    Re: Cleaning of slow shutters

    A quote from Carol Flutot's website at: http://www.flutotscamerarepair.com/Tips.htm

    Q What's the best way to store a shutter?

    A Keep it in a dry area (off the floor if it's cement, like in a garage). Best to set the speed dial on "T" or "B" and uncocked so there is no tension on the springs. To keep the shutter in shape, you should take it out and exercise it at least once a month, running through once at each speed, and at least 10 times at the lower speeds, to get that slow gear governor moving. Even if you're too busy or have too many shutters... get them out once in a while throughout the year and exercise them or they'll become sluggish over time.
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

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