!!! Be careful when using liquid near electronics. Plan ahead in case there is a spill, work carefully !!!
This is an updated version of our original magnetic stirrer. The main addition is a magnetic stir bar that make the system 2-3 times more powerful without changing the fan or design.
To assemble the stir bar, you need to either glue it closed, or more preferably, use PLA plastic friction welding ( http://hackaday.com/2014/12/30/3d-printing-technique-friction-welding/ ).
There is a spacer inserted below the cover to add extra space between the magnets on the fan and the stir bar. Without it, the magnetic field will be too strong and prevent the fan from turning. Also, your fan may differ and so might your magnets. You might need the spacer or not, or you might need to print 2 or more and stack them.
Tuning your stirrer requires a little patience and some trial and error until you get consistent, reliable results. Also note that the container you use should have as flat and as thin a bottom as possible. We have found that from glass jar to jar, performance differs because of the thickness and shape of the bottoms of different jars.
We included the SketchUp file which contains the original version and all the updates.
Full list of changes:
(2x) 13mm nickle plated neodymium magnets added on the 80mm 12v DC fan;
a 1mm spacer for adjusting the height between the fan and the stir bar;
a stir bar for (2x) 6x4mm nickle plated neodymium magnets and;
new cover that allows for easier removal when the power adapter is plugged in.
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