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Thread: Motorized rocker for tray developing

  1. #1

    Join Date
    Jan 2015
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    Motorized rocker for tray developing

    I started shooting X-ray film and developing the negatives in trays got old pretty fast so I've been working on a motorized rocker to make it all a bit easier
    Made from some wood sheets, some 3d printed parts and a windshield wiper motor.

    I have not tried it yep so we will have to see if it works alright, maybe it's not enuff of a rocking motion.

    Here are som pics










    And a short video



    I can upload the 3d files if someone else would be interested of making their own.

  2. #2
    Tim Sandstrom
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    May 2006
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    San Jose, CA
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    244

    Re: Motorized rocker for tray developing

    this is awesome! I might place the tray on a slight diagonal to get more randomness, or add a little eccentricity to the cam.
    I think the concept is sound and your implementation is relatively frugal and elegant, nice work!

  3. #3
    Jac@stafford.net's Avatar
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    Dec 2012
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    Re: Motorized rocker for tray developing

    If it doesn't work out, then use it as a platform for a kitty litter box. If you hate cats.

  4. #4

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    Jan 2015
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    Re: Motorized rocker for tray developing

    Thank you.
    I was planning on rotating the tray some during devloping to add some randomness

    This is how the cam looks now and any suggestions on improvements is highly appreciated


  5. #5

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    Hemel Hempstead, UK
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    Re: Motorized rocker for tray developing

    I'd be tempted to slow the motor to about half the speed; it looks as if the fluid is mainly moving in place rather than moving across in bulk.

    Neil

  6. #6

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    Jan 2015
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    Re: Motorized rocker for tray developing

    I do have a speed controller which I intend to use to set whatever speed I want
    Last edited by OeT; 11-Mar-2017 at 11:54.

  7. #7
    Jac@stafford.net's Avatar
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    Re: Motorized rocker for tray developing

    I have a couple motor driven drum spinners. Randomness is assured by having one eccentric wheel, the other a uniform dimension. If this hint does not help I will try to find time to draw it up.

    ...and thanks for putting up with my earlier wise-crack.
    .

  8. #8
    Eric Woodbury
    Join Date
    Dec 2003
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    1,115

    Re: Motorized rocker for tray developing

    It needs to run slow enough that it isn't near resonance. You could cut you rocker speed in half by using a circular wheel and offset the center of rotation.

    What's your motor? Is that a car window motor?

  9. #9

    Join Date
    Jul 2006
    Location
    Collinsville, CT USA
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    616

    Re: Motorized rocker for tray developing

    When I was at RIT in the 1970s, remember seeing several random agitation rigs.
    From what I remember:
    They held up to 3 16x20 trays.
    They used 2 rotating oval cogs at 90 degrees to each other and placed at opposite ends (right and left)
    The rocking motion was way slower that you'd expect, and way less than you'd expect.
    "Board" under the trays was either Plexiglass or gray PVC.
    Wish I had taken a picture of the rigs....

  10. #10

    Join Date
    Jan 2015
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    43

    Re: Motorized rocker for tray developing

    Thanks for all the feedback
    I am going to try it with a more square wheel to give some more time at the end of the rocking motion.
    This combined with a offset center might be the way to go?



    If you have any other ideas please share an I will try and test them.

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