mycotheologist
Hazard to Others
Posts: 154
Registered: 16-3-2012
Member Is Offline
Mood: No Mood
|
|
Devising new types of stirrers
I love magnetic stir bars but its often a pain in the ass getting a hotplate/stirrer under the reaction flask when using a particular apparatus so I'm
wondering how to improvise alternative devices for reactions that don't require heating. Devices that are small and easy to implement in any
apparatus. I have a good few neodymium supermagnets which will be perfect. I have some magnets this size:
which I'd been using as fridge magnets. They're so powerful I can't pull them off the fridge, I have to slide them to the edge so the big ones will be
able to interact with the stir bar from a good distance.
What I have in mind is a tiny little device that you can fit in anywhere, which would serve as a convenient alternative to using one of those big
stirrers that you have to place under the flask and make sure the flask is close enough to the magnetic field. What I have in mind is a little device
that you can attach directly onto the flask. So the bare necessities for what I have in mind would be some kind of plastic fan blade or something:
to hold the magnets. A little DC motor:
to turn the fan blade. A potentiometer
to vary the rotation speed. And some batteries to power the motor. Even that thing would be inconvenient though cuz you'd have to place it under the
flask though.
Heres a novel idea. A plastic ring that is hollow on the inside. Inside the hollow cavity is grease and neodymium magnets, and something to separate
the magnets from each other. Hydraulic pressure could be used to make the magnets travel around the loop. This ring could be clamped just like a ring
stand (in fact it could be used as a ring stand too) but bigger rings could also be clamped around the flask (rather than under it like a ring stand)
or over it so as not to interfere with the apparatus (i.e. the way a ring stand prevents a flask from being lowered into an ice bath. I might be
dreaming with this second idea though, I'd have no idea how to make something like this myself. It would be pretty cool though.
|
|
|
tom_servo
Hazard to Self
Posts: 52
Registered: 11-11-2008
Member Is Offline
Mood: No Mood
|
|
Just use a PC fan, rare earth magnets out of an old HDD, the PC Power supply and a PWM controller
DIY Stir Plate
|
|
|
Hexavalent
International Hazard
Posts: 1564
Registered: 29-12-2011
Location: Wales, UK
Member Is Offline
Mood: Pericyclic
|
|
I once built my own mag stirrer using an old bulky PC fan and a large neodymium magnet with a 12V DC power supply . . .it worked a treat and was small
enough to fit pretty much anywhere in my lab.
Regarding stir bars themselves, I think Magpie once discussed how you can make your own with materials from online or locally . . .seems like a nice
idea for weird apparati, especially custom glassware jobs where the usual shapes just aren't practical
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
