Build a magnetic stirrer ?

Discussion in 'Darkroom Equipment' started by Smudger, Mar 24, 2006.

  1. Smudger

    Smudger Member

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    Hi all. I would like to give this a try. I have the components : motor,magnets etc, but my lash-ups don't work. Has anyone looked inside one of these devices?
    I would welcome advice on the layout of the magnet/s inside the base.
    And, is the stirrer bar a magnet, or simply a steel bar?
    All information gratefully received.
     
  2. Dave Parker

    Dave Parker Inactive

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    My Sidekick processor uses a "magnetic pill" stirring system, it is a iron pill that is activated when you start the processing, that spins the pill to keep the chems mixed, pretty simple system. You might get a hold of the guys at Phototherm, as they use this type of stirring system in many of their products.

    http://www.phototherm.com

    Dave
     
  3. avandesande

    avandesande Member

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    the stir bar is a teflon coated magnet.
     
  4. Dave Parker

    Dave Parker Inactive

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    Could be, I thought they told me the one in my processor is iron, alls I know is it works.

    Dave
     
  5. L Gebhardt

    L Gebhardt Subscriber

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    Last I looked you could get magnetic stirring hot plates for dirt cheap on ebay.
     
  6. avandesande

    avandesande Member

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    I was really talking about the ones you generally buy from chemical supply. Not sure about yours....
     
  7. glbeas

    glbeas Member

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    The stirrers use a strong bar magnet on a rotor under the plate, usually one of the super strong exotic alloys. The stir bar is a smaller but similar magnet encased in plastic.
     
  8. 25asa

    25asa Member

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    What would one have to do to use a kitchen blender?
     
  9. glbeas

    glbeas Member

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    You could engineer a bar to fit the motor shaft and a plate to sit on top of the unit. Most blenders go so fast though the bar would not be able to couple to the base magnet even at the lowest speed. It would likely just sit and vibrate.
     
  10. JLMoore3

    JLMoore3 Member

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    Why not just use a kitchen blender for your mixing? I've been using one dedicated to the darkroom- works for me.
     
  11. vet173

    vet173 Member

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    The problem with a blender that I see is that you would be introducing a lot of air into the solution. Not good with stuff that oxidises.
     
  12. pnance

    pnance Member

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    I have two stirrers. One has a bar magnet which is hard to control, it either spins too fast and or loses control of the stirring magnet.

    The other is a Corning heater/stirrer, the magnet is a round device like a donut, better balancing, and has very good slow speed control.
     
  13. Smudger

    Smudger Member

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    Thanks to all who responded. I will continue my experiments..
     
  14. donbga

    donbga Member

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    I have to ask why? High quality used stirrers can be purchased on e-bay. Spend your time making photographs.

    Don Bryant
     
  15. Gerald Koch

    Gerald Koch Member

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    This problem can be remedied by the choice of the proper size bar. One size does not fit all containers.
     
  16. Gerald Koch

    Gerald Koch Member

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    My stirrer has a very thin aluminum top surface in order to get the two magnets as close together as possible. Another design consideration is to get the internal bar magnet properly centered on the motor shaft so that there is no vibration. The motor must be chosen for its torque and maximum speed. A lot of design problems. Considering they are not that expensive I would just buy one wither new or used.
     
  17. Gerald Koch

    Gerald Koch Member

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    My concern in using a blender is their small capacity and mixing too much air into solutions.