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Magnetic stirrers


#1

G’day; Someone was asking about magnetic stirrers. In the '60s
it was almost impossible to get anything slightly unusual in NZ
(including money) - we were very isolated. But the Stage 1
Chemistry lab in the University where I worked needed a dozen
small, slow speed stirrers, urgently. So we managed to get a
dozen little electric clock motors, epoxied small, powerful
alnico magnets to the shaft, and fastened them into small
airtight plastic boxes. Next we found in a toyshop some 1"x1/8"
bar magnets which we sealed into Pyrex glass tube. So, put the
beaker/flask etc on the box, connect to the mains, put the
magnetic follower into the liquid in the vessel - and voila! - a
dozen magnetic stirrers in two days! But we didn’t get thanked;
it was part of the job.

    /\
   / /    John Burgess, 
  / /
 / //\    @John_Burgess2
/ / \ \

/ (___)
(_________)


#2

John,

TO THE RESCUE AGAIN(AND AGAIN)!

But, a couple of questions…

    • u attached the bars to the clock shafts… do u mean the
      clock arms??

– What are ALNIVO magnetic and where would I get them today??

– I’m sure we can come up with the stirring elements per the
people who are selling mag units today

– How fast would the unit turn … RPM…would this be fast
enough for a mag unit as per demo’ed in shows… My guess is
that the RPM is about 60 RPM give or take 20 RPM(COMMENTS …
IF U HAVE SEEN THE UNITS!!!)

We’re Goin Build a mou 'tain!! … hopefully

Jim


#3
- -  u attached the bars to the clock shafts... do u mean the
clock arms??  

G’day; yes. The motors we bought didn’t have any gearing, and
the shaft rotated at 60 revs per minute; SLOW - don’t confuse
stirrers with magnetic polishers! And they weren’t bars; they
were little cylinders.

    --   What are ALNIVO magnetic and where would I get them
today??

Sorry but it’s Alnico; short for aluminium, nickel, cobalt.
Don’t know where you’d get them in the USA; I live on the other
side of the globe. Most tool shops have them here. Modern
ceramic magnets are more powerful. If you can get them – How
fast would the unit turn … RPM…would this be fast enough for
a mag unit as per demo’ed in shows…

As fast as a second hand. I’ve never seen “mag units demo’d in
shows”; shows are like hen’s teeth where I live. Last one I saw
was in Wellington 25 years ago, 200 miles away across two
mountain ranges and a nasty bit of water. We made the magnetic
stirrers which were urgently needed to stir corrosive liquids in
narrow-necked vessels in a University chemistry lab. Because we
couldn’t buy them. Cheers,

        /\
       / /    John Burgess, 
      / /
     / //\    @John_Burgess2
    / / \ \
   / (___) \
  (_________)