Magnetic stirrer and springs.... Answered
Wanted to try how far the magnetic field of my new stirrer is reaching and observes something weird...
If you have a normal stirring rod in a beaker then these things do excatly what they are supposed to.
Even if you try to add the rodd to an empty beaker while the stirrer is already running.
The first option gives you a nice rotation, the later often just some jumping and bouncing rod.
Fun fact though: Inside a stirrer rotates a magnet and the rod is just a steel bar enclosed in polyethylen or teflon.
Trying to make a stirring rod roll around the center instead of rotating is next to impossible - it always tries to use the max binding force and centers itself.
So I tried different things for the end goal of designing a stand up stirring twoer instead.
You know, like these fancy ones found in huge water towers to agitate the water.
I found a small steel ball with two magnets attached quite interesting but an accident made me wonder...
For some reason I did not turn the stirrer fully off when searching my little box of goodies for new stuff to try.
A small spring for some motor bushes landed on the stirrer...
And although it moved dead center it did not spin at all.
A slight vibration was all I could see.
First weird behaviur happen when I tried to move the spring around to check why it is not spinning.
Pushing it a bit lengthwise suddenly made it spin!
A bit of fiddling a trying showed it works best slightly off center to the magnet with one end while sitting on the radius.
The spring rotated like a horizontal drill but in no relation to the stirring speed.
Second and even weirder things happened when the spring slipped through my fingers.
It started to roll around the center of the plate but in the opposite direction to the magnets rotattion!
An increase in speed made it roll faster until the g forces made it fly off the plate.
If you have a magnetic stirrer then try it out one day.
I have a few theories why the spring starts to rotate or roll but none make fully sense.
Can try to take a video for those with no stirrer but for the fun of it it might be good to just mount a magnet on a motor and try LOL