stirplate: fridge magnet works (for me)

[horsey]

I built a stir plate out of a cardboard cigar box, computer fan, hard drive magnet, and a glass apple juice jug. I was having a hard time getting the stir bar to spin effectively on the round bottom of the apple juice jug or perhaps it was the the cardboard cigar box but after a lot of messing around I ended up swapping out the hard drive magnet with a round refrigerator magnet and now it works great. So if anyone else out there is having problems with their DIY stir plate this may work for you as well.

 

[kansasbrew]

That must be one heck of a refrigerator magnet you got there.

 

[mattd2]

Can't speak from experience because I have never made/used a stirplate (yet), but did you have the hard drive magnet setup like the fridge magnet in you picture? or is the picture before you actually glued it to the fan? I always thought you needed 2 harddraive magnets positioned on either side of the fan centre, but again I have never actually made a stir plate!

 

[horsey]

I never tried to use 2 hard drive magnets. I don't even remember what I did with the other one. To be honest I built this thing last summer and since I didn't have a stir bar, it sat there without ever being fully tested. So I ordered some things from northern brewer and picked up a 25mm stir bar as well. The hard drive magnet kept sending the stir bar to the sides of the apple juice container. I figured either my fan was spinning too fast, the hard drive magnet was to strong, the bottom of the jug was too round, and/or the cigar box lid was too thin. So I had a kind of "why not" moment and saw this magnet stuck to the fridge (I think it had a bottle opener glued to it at one point in time, so it's a little big I suppose) and threw it on the fan and it worked. I didn't glue the magnet down, it sticks to the magnets in the fan motor I'm guessing. (I'm not good with motors, electronics, tools, or anything of that nature.) I don't know if you can tell by the picture but I took a PC fan from an old 486 computer, wired a small power supply that I think came from a charger from a toy RC car, and screwed it to a board, and then stuck the board into an empty box of "It's A Boy" bubble gum cigars.

I have the magnet out towards the outside of the fan blades like in the picture. I tried with the hard drive magnet on the outside and right in the middle and couldn't get either way to work. So funny as it may sound, I just threw this fridge magnet on the middle of the fan and plugged it in. The magnet slides to the outside and the only thing stopping it from being thrown is the fact that the fan blades are just a little lower than the outer "cage" of the fan.

I don't know, I'm not a handy guy and the only money invested into this thing was the $4.25 for the stir bar. Bottom line I guess is that it works so if if you got an old PC sitting around (and you're sick of shaking your yeast starter) you may be able to slop something together like I did. Maybe in the future I'd build myself a nice one but for now this one seems to be working.

 

[EricT]

I followed the directions as per the DIY Stirplate thread myself. It didnt really work for me either. I had to separate my magnets by about 1/4 inch since I was using a bigger stir bar (2"). I tried the single magnet in the middle and it was a no go. I then put the two magnets end to end guessing which was north and which was south and evidently got it wrong so had to switch them around again. After about 4 different configurations I finally got it and it works great. the only concern with your setup would be the imbalance of a single magnet as its positioned on the outside of the fan blades. How long have you had it running for at a given time? If it works, great! but I think I would put on a counterbalance just so it lasts longer.

 

[mattd2]

Bottom line I guess is that it works so if if you got an old PC sitting around (and you're sick of shaking your yeast starter) you may be able to slop something together like I did. Maybe in the future I'd build myself a nice one but for now this one seems to be working.

fair enough call, sometimes things do get overthinked and you need someone to just "slap" something together that works to realise how easy it is. The main thing putting me off building a stirplate is ripping apart a computer to get all the bits needed, now it looks like I might not need to

 

[L0F]

So, how does the magnet work?

 

[passedpawn]

I'd love to see a youtube video of that thing working.

 

[horsey]

Here it is. My knack for high quality film making almost rivals my knack for building high quality stir plates.