Build a magnetic stirrer ?

Smudger · Mar 24, 2006

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.

Dave Parker · Mar 24, 2006

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

avandesande · Mar 24, 2006

the stir bar is a teflon coated magnet.

Dave Parker · Mar 24, 2006

avandesande said:
the stir bar is a teflon coated magnet.

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

Dave

L Gebhardt · Mar 24, 2006

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

avandesande · Mar 24, 2006

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

glbeas · Mar 24, 2006

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.

25asa · Mar 24, 2006

What would one have to do to use a kitchen blender?

glbeas · Mar 24, 2006

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.

JLMoore3 · Mar 24, 2006

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

vet173 · Mar 24, 2006

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.

pnance · Mar 25, 2006

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.

Smudger · Mar 27, 2006

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

donbga · Mar 27, 2006

Smudger said:
Thanks to all who responded. I will continue my experiments..

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

Don Bryant

Gerald Koch · Mar 28, 2006

pnance said:
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.

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

Gerald Koch · Mar 28, 2006

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.

Gerald Koch · Mar 28, 2006

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

Build a magnetic stirrer ?

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