Super Stirbar

bio · Working Bee

Does anyone have one of these samarium/cobalt stir bars?

http://service.belart.com/cat/371740000.html

I'm thinking of getting one and was wondering if they are all the're cracked up to be?...... "transmits torque loads 2 to 3 times larger than those of conventional stirring bars of this length significantly improving efficiency.".... At $65 a wack for a 50mm (one size only) it should be pretty damn good. My octoganol 4x1/2 incher was only $20 and easily stirs a couple gallons unless it's thick sludge.

While you're at it check out this stirrer. ...."effectively mixes liquid volumes from 10 liters up to 208 liters"...

http://service.belart.com/cat/370280001.html

Definetly want one of these babies.The 12inch stirrer/hotplate I have is stalling out a lot lately. Wink

Will maybe try retrofitting some more powerful mags. I hear the neodyium ones from old generation hard drives are waaay powerful. Anybody ever try this?

MargaretThatcher · Sat Apr 23, 2005 10:44 am

Samrium-Cobalt is the dog's bollocks of magnetic media: very powerful and yet reistant to high temperature demagnetisation. If you have the cash to splash, then do so (otherwise make do with the usual model)

(cheaper stirbars are AlNiCo, which have a fairly high Curie temp. but low strength).

primathon · modified

Neodymium Iron Boron magnets are sensitive to heat. If a magnet heated above its maximum operating temperature (175°F/80°C for standard N grades) the magnet will permanently lose a fraction of its magnetic strength. If they are heated above their Curie temperature (590°F/310°C for standard N grades), they will lose all of their magnetic properties. Different grades of neodymium have different maximum operating and Curie temperatures.

http://www.kjmagnetics.com/specs.asp

Further Information: http://www.kjmagnetics.com/neomaginfo.asp

icecool · Insistent Chemist

I happen to have such a stirbar...

bio · Working Bee

MargaretThatcher · Wed May 04, 2005 6:34 am

Bio: just read your comment about hard-drive magnets. Yes, they are very powerful, but you might have problems retrofitting them to an existing stirrer: firstly, the pole geometry will not be optimal and secondly, balancing them is a real bastard. If you don't get the magnet balanced, you will know it at 1300 rpm.

bio · Working Bee

Still trying to rustle up an old generation hard drive to scavenge. I quess the new ones only have piss ant magnets. Technology advances and companies like Applied Magnetics go under cause nobody wants there stuff anymore. Some good info here on these mags.

http://www.wondermagnet.com/other/gentest.html

Balancing is a bitch. I found out the hard way and never even got close to 1300RPM. Was nice and smooth going slow though, lol. Also the motor in my stirrer just has a damn rheostat for speed control so the AC motor torque goes all to hell when the voltage drops even to half speed equivalent, maybe 80-90V but didn't measure it I deally for AC a switching pole setup would be ideal but PM motors are better.
There has got to be a way that's easier than this

http://www.otherpower.com/otherpower_experiments_motor_convert.html

to up the slow speed torque using the existing motor so am racking my
brain on this. Phase control is no good torque wise but maybe I could tap everyother pole to a selector switch which would give half speed full torque. (Whoops that's ass backwards, so much for brilliant ideas. ) At least theoretically.

grandpa · smurf

My 2 cents

Stirrbar like this one are certainly fine,
but I will suggest you to try to find a (used) IKA brand stirrer, compared to a "corning" stirrer they have a much more powerfull magnet.

Shocked

IndoleAmine · Dreamreader Deluxe

If a corning won't do, an IKAMAG will not do much better - just slightly, that is.

At least in my experience (I prefer IKA too, though for other reasons)..

Maybe better switch to a nice overhead stirring motor instead, its very cheap if bought used and, together with a heating mantle, also VERY applicable to big scale rxns instead of the usual hotplate/mag.stirrer/oil bath combo...

i_a