from spiritplants...
Materials:
A motor with a shaft
A dimmer switch
Some plywood
A magnet with a sufficiently strong field
An extension cord
The motor: I used a small sump pump that had a long copper shaft with a blade like ending used to create the flow of water. Cut the end off and removed all of the casing except for that of the motor itself. Any decent sized motor will work though, but I recommend you get one that has a fair amount of power... You may not think you need it but it really comes in handy stirring thick goop (such as concentrated plant extractions)... If you cannot find a motor with a shaft ('ya didn't look very hard then, piker) you can always try to mount one on the motor, but make sure it is ABSOLUTELY straight, or your stirrer will be a useless noise maker... Puttering around in the shop, I found an electric welder to be the best way to mount a shaft, and I had some real problems with epoxy...
Take a strong magnet and mount it to the shaft of the motor. I used a magnet from a 100 Watt car stereo speaker, one of the circular ones... This was problematic, because the flat sides are each a seperate pole. I had to take a grinder and grind two of the round sides flat so that I could mount it on the shaft with epoxy... You want to have the surface with two poles at the face of the stirrer where it will approach contact with the bottom of the glassware... That way it will hold the magnetic stir bar firmly, without repelling either side of it and increasing (guaranteeing) that the bar will fly off and lose contact with the magnet. If you are not using a magnetic stir bar (I highly recommend it) this won't matter, but 'ya might as well do it right the first time... Edmund Scientific has cheap magnets that are perfect for the job, and they have a web presence...
Here's the tricky part, unless you have access to a wood shop... Making the structure it sets in, but it is also the least important set as long as the stirrer is 1) VERY Stable and 2) Has a top surface sufficiently large to hold your glassware.
Never use plastic and do not use plexiglass to top the stirrer, it will melt at the first contact with many solvents and then your stirrer will be a friggin' mess...
I cut a 12 inch circular base and matching top, the top has a hole approximately 3/4 inch for the magnet, and when constructed the magnet was 1/16th of an inch below flush... Remember you do not want the magnet to make any contact with your glassware... I was lucky in that my motor had a plastic case with a threaded holes to mount the motor, and I simply screwed it in to the base... Epoxy would more than likely work, but make sure your base is rigidly attached or you may wake up after an all night stir session and find everything lying on the floor in a puddle of caustic lye... And boy will your land lord be happy...
The sides of the stand are pretty much height dependent upon the length of the shaft on your motor... Mine are two 9 inch wooden squares, one with a hole cut through it to mount the dimmer switch... (see below)
Alrighty... If your motor has connections, strip the female end off your extension cord and wire it in right, use a drop or two of solder, or your old friend, electricians tape to hold it firmly in place, making 100 percent positive the wires are seperate and will not short... Cut the extension cord in half, and wire it to the dimmer switch, and then wire the plug end in to the other side of the switch... Now mount that puppy, either by screwin' it in as I did above, or by screwin' it in to the base... Remember, you want this puppy to run for hours at a time, so WIRE IT RIGHT OR YOUR HOUSE WILL BURN DOWN AND YOU WILL REGRET YOUR LAZINESS...
The top of your stirrer need to be FLAT... Check it once, check it twice... I am considering mounting a very thin piece of glass to the top because the spills discolor the wood, but hey, I don't think this is a beauty contest... One thing you need to be SURE of, is that the solutions cannot spill down into the motor if the flask overturns, frothes over, etc... It will short circuit the motor, ruin it and most probably YOUR HOUSE WILL BURN DOWN AND YOU WILL REGRET YOUR LAZINESS... I made a sheet metal shield, a simple cone that fits around the shaft closely without touching... Its just a cone that has a shaft sized hole in one end... Mounted it to the motor with our old friend epoxy... Glass would eliminate this problem...
Alrighty now, a hex bolt makes a decent stir bar, just make sure it is non-reactive, but you really can't beat the real thing... Fungi Perfecti has a beaut', but you can get them a variety of places, as well as borrow them from a universtiy laboratory... Not that *I* would do anything like that, seeing a how tuition costs are so low, and how well you are treated by universities to begin with...
Alrighty then, I'll post this and look back over it later...
This stirrer will completely transform the efficiency of your extractions folks, you can leave it on low for days on end... I cannot stress the benefits of using one... Yields are substantially improved, emulsions are almost completely eliminated due to replacing shaking with stirring, and most likely you will meet a beautiful sex partner with inordinate amounts of money and a nice car after completing it, once they see your practical ingenuity and outright scientific cunning...
Total cost, prolly less than 30 dollars, I used scrap wood and piece parts lying around the shop, my cost: $2.49 for the epoxy, and I still have over half a tube left...
Raver...