Stupid Simple Stir Plate. ~$12

[TorMag]

you'll have issues with that. block magnets have the north and south poles on the larger surface. it will stick to the fan just fine but the stir bar wil want to stand on end. you need to place two block magnets end to end to get the desired effect. you'll either need to cut it in half (hard to do) or get some smaller ones.

So is there a good magnet on Amazon to use?

 

[olephart]

Gavin,

It looks like quite a few people have been reading this article, recently. See the attached screenshot from amazon. Funny that a computer fan would be bought by people also looking at flasks, stir bars, and project boxes.

Haha, gotta love messing with the marketing data. 😂

 

[bionut]

This is my stupid simple build. First time i used a DVD case as a box, but it was too thin to hold the flask so i made a box from some scrap OSB boards. The speed controller is made by me as well. I power it with a phone charger so the vortex is smaller even at full speed.

 

[lincolnubrewer]

Has anyone buy the mag craft magnet from home Depot? Free shipping to the store. They have multiple sizes and come in rods, discs,cubes, and blocks. The one I was looking at is nsn0635 2"×1/2"×1/8" block and has 12lb pull force. I was thinking of cutting in half. Am I ok with this magnet?

 

[itsnotrequired]

So is there a good magnet on Amazon to use?

i ordered these direct from magcraft:

http://www.rare-earth-magnets.com/magcraft-nsn0834

 

[CJ-3]

Finally got around to making mine today, this fan works very well. Got a starter going already.

Thanks again for posting about the fan!

 

[CJ-3]

Has anyone buy the mag craft magnet from home Depot? Free shipping to the store. They have multiple sizes and come in rods, discs,cubes, and blocks. The one I was looking at is nsn0635 2"×1/2"×1/8" block and has 12lb pull force. I was thinking of cutting in half. Am I ok with this magnet?

I bought these from Home Depot and put my stir plate together this morning.

http://www.homedepot.com/p/MASTER-MAGNETICS-1-2-in-Neodymium-Rare-Earth-Magnet-Discs-6-per-Pack-07046HD/202526367

It is a 6 pack of 1/2" magnets. I have 2 of them on the fan and my stir bar spins darned near perfectly without being thrown. I have a 1500ml starter spinning right now and only need to run the fan at half power.

 

[TorMag]

So what have I done wrong? My stir bar does not spin around but rolls, like a log rolling down a hill.....

 

[day_trippr]

Pictures might be helpful...

Cheers!

 

[AkBrew907]

Something with your magnets would be my guess. Might have to flip one side over

 

[itsnotrequired]

So what have I done wrong? My stir bar does not spin around but rolls, like a log rolling down a hill.....

do you have a single, large bar magnet across the washer on the fan? or multiple smaller magnets as indicated in the original post?

 

[TorMag]

do you have a single, large bar magnet across the washer on the fan? or multiple smaller magnets as indicated in the original post?

This is my set up so far
View attachment ImageUploadedByHome Brew1466699257.758885.jpg

 

[TorMag]

I've noticed that the bottom of the flask I got is concave. I think this could be the problem?

View attachment ImageUploadedByHome Brew1466699439.842804.jpg

 

[day_trippr]

What happens if you lay the stir bar directly atop the middle of those stacked magnet?

Cheers!

 

[TorMag]

What happens if you lay the stir bar directly atop the middle of those stacked magnet?

Cheers!

I will try that when I get home tonight.

 

[day_trippr]

Those bars physically look like the ones I used on my builds (although I only used one pair per each).
Mine are "broad face polarized" so the entire broad side is a pole, with the opposite pole on the other side.

Hopefully you got the same type, as I'm not sure what the heck happens if those are end-polarized...

Cheers!

 

[TorMag]

Forgot to take a picture when I got home, but I did place the stir bar on top of the magnets and it stuck to the middle. Overlapping both magnets equally.

 

[itsnotrequired]

I've noticed that the bottom of the flask I got is concave. I think this could be the problem?

the curved bottom certainly doesn't help the situation. mine is fairly curved as well and if i crank up the speed beyond halfway, it is very likely the bar will be thrown. i use a 2" bar in a 5 liter flask. my bar is also very loud when in operation (clinking against the glass). i tried some o-rings on the bar for sound deadining but the bar was thrown even on the lowest setting. now i just setup the stir plate in the unfinished part of the basement and noise is not an issue. i'm going to try a 1" bar in the future and see if that helps.

another trick that worked from me is to place a thin fender washer on top of the magnets. it seems to 'spread out' the magnetic field and my bar makes less noise, implying to me that it is more balanced when spinning.

 

[mattrox]

I finally got a box to put mine in.

View attachment 1475745688805.jpg

View attachment 1475745702566.jpg

 

[Partagas]

I was wondering if cutting the top off like in the picture is a must. Would it work without cutting the circle? Or would i need stronger magnets (those have a pull of 4.83lbs only) if i wanted to skip that step?

 

[Gavin C]

I was wondering if cutting the top off like in the picture is a must. Would it work without cutting the circle? Or would i need stronger magnets (those have a pull of 4.83lbs only) if i wanted to skip that step?

All depends on the height of the box. No need to cut a hole if the setup can spin underneath the box lid and not be too far from the stir bar in the flask. The magnets in the OP are beefy. Not cutting a hole if the box allows should be a non-issue.

My assaulted cigar-box is as ugly as they come. Hole for necessity. YMMV

 

[TorMag]

I have the plastic box, no hole needed in mine.

 

[Partagas]

My attempt turned out pretty cool. Midway through the build i found a bigger box from a gun cleaning kit which was perfect since i will be doing 5l starters.
View attachment ImageUploadedByHome Brew1488821284.878784.jpgView attachment ImageUploadedByHome Brew1488821523.087664.jpg

 

[Gavin C]

My attempt turned out pretty cool. Midway through the build i found a bigger box from a gun cleaning kit which was perfect since i will be doing 5l starters.
View attachment 391678View attachment 391679

Very neat build.

 

[augiedoggy]

the case that a 100 (or less) cd/dvd roms come in works well too.. it holds the flask perfectly centered too...

 

[VagueSkunk]

Quick question for those harvesting magnets from old HDDs:
I've managed to disassemble a couple old, dead HDDS and remove the magnets from them. Unfortunately the magnets are affixed in some unknown way to an oddly shaped, kind of curved 'backing plate' for lack of a better term. There are no screws or fasteners that I can see holding the magnet in place, so I'm assuming that an adhesive is used.
So, how are you removing the actual magnet from this backing plate?

 

[arnobg]

Quick question for those harvesting magnets from old HDDs:
I've managed to disassemble a couple old, dead HDDS and remove the magnets from them. Unfortunately the magnets are affixed in some unknown way to an oddly shaped, kind of curved 'backing plate' for lack of a better term. There are no screws or fasteners that I can see holding the magnet in place, so I'm assuming that an adhesive is used.
So, how are you removing the actual magnet from this backing plate?

I used vice grips to hold the backing plate while using a flathead screwdriver to wedge between the magnet and plate and pry off. It popped off this way, yes it had an adhesive between them.

 

[VagueSkunk]

I used vice grips to hold the backing plate while using a flathead screwdriver to wedge between the magnet and plate and pry off. It popped off this way, yes it had an adhesive between them.

Thanks!