My Stirplate... Cheap and Easy Build...

Easiest way is to put a volt meter on it.

Otherwise if you don't have anyone you can borrow from, just hook it up. With 5 volts dc, it isn't a safety issue. It will run backwards one way (reversed polarity).

Use a multimeter. You can frequently get a cheap one at harbor freight for like $3. Any crappy one will do tho. Analog or digital doesn't matter.

The fan is supposed to run clockwise right....so if I get it backwards it would run counter right? This means I could reverse it. Does it even matter which way the fan turns? I am using a 12vdc power supply.

Depends on the fan. Mine won't turn in one direction depending on polarity. The one I used previously wouldn't either. It just depends on the design. Mine were larger more expensive fans tho. If you plug it up and out doesn't turn with no load unplug and switch the leads and you'll probably be fine even if you have a fan that prevents counter rotation.

rlynge said:

Thanks for the quick reply! How do I know which is positive and which is negative?

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You will know you have it right if the fan runs. If it doesn't run, reverse the wires. It won't do any harm if you have it backwards on the first try, it just won't run.

If it runs your fine. I don't think most fans are set up to matter. It's cheaper to just let the electromagnetic field control the direction. They just usually are capable of less torque.

I've never had a fan which actually ran backwards (I've tried with 3 of them). Either way, there's no harm in trying to connect them both ways.

Jinx!

Tried it and it worked....thanks guys! I will finish the build soon!

Hope you have better luck balancing than I did. My new plate is neither adjustable nor well balanced.

Well I think I am going to do what Jakecpunuts did and use velcro to attach the washer. That way it should make it easier to adjust the balance.

Is great if you have the room. My tolerance was really thin. With magnets I have less than 1/64" to the top of my box.

We shall test it out and see....I have to go pick up some bolts, velcro, and some spacers to finish it. I might pick up some slow setting epoxy just in case. I am using a fan from an old dell(2001)....hopefully it works well enough!

So while I was at publix I just so happened to see some velcro. Of course I bought it so that I could work on my stir plate some more. I got my washer set in a pretty balanced manner. I was going to use the magnetism of my HD magnet to attach it to the washer but the fan throws it off. Should I glue it or should I buy some of the magnets suggested by the OP?

nice

Bump

After centering my washer on the fan, i glued it on then I used that tacky putty you can use to put up posters to get the magnet centered. Using tuis putty allowed me to move the magnet around and start up my stirbar to make sure it won't get thrown. The magnet is actually so well attached to the washer with the putty, I haven't glued it down.

There two different magnetizing types used on hd magnets. Some I pulled out of a scsi drive were perfect axial setup so I used one on each end. The recent one I built I had to snap some hd magnets in half but stacking have the power I needed. Alternatively many on here have bought disc or bar magnets with great results. I hear balancing is easier doing that. It just depends on your budget and/or need are. I'm broke atm so my total investment (other than the stir bar that I already had was $0.28 cents.

Maybe I will snap mine in half and give it a try. Worse thing that could happen is that I need to by magnets. The thing that kills me is that the magnets are wicked cheap but then they rape you on the shipping. A $2 magnet costs $8 to ship. That doesn't make sense.

The target is to have north on one side and south on the other. TBH I don't really understand why the halves work better but I tried a singles, doubles, and halves (both single and double) and only my old axial mags were better than the doubled halves.

Edit: Please note, the halves were magnetized through the length of the magnet rather than through the thickness (aka axially). I thought when you snapped them in half the north side near the south end then becomes the south end but it doesn't seem to act that way for me.

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rlynge said:

Maybe I will snap mine in half and give it a try. Worse thing that could happen is that I need to by magnets. The thing that kills me is that the magnets are wicked cheap but then they rape you on the shipping. A $2 magnet costs $8 to ship. That doesn't make sense.

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Go to Ace Hardware that is if you have one near you and get these. They work great and the are much cheaper than they are listed here. I got 2 packs for $6 out the door and my 2" stir bar pulls a helluva cone to the bottom of the flask.



http://www.acehardware.com/product/...0.2628078.1259402&lmdn=Brand&searchId=1259402

I just got some from KJ magnets and let me tell you those are some strong magnets. I just have to make a trip to the hardware store and I should be done with this build some time this week!

I thought that I would post what I bought today to build my stir plate.

I bought this fan (Comes With Fan Controler!!!)
http://www.newegg.com/Product/Product.aspx?Item=N82E16835200020

$7.99 - $1.59 (Discount Code BTEKAJA22) + Free Shipping = $6.40

mredge73 said:

I thought that I would post what I bought today to build my stir plate.

I bought this fan (Comes With Fan Controler!!!)
http://www.newegg.com/Product/Product.aspx?Item=N82E16835200020

$7.99 - $1.59 (Discount Code BTEKAJA22) + Free Shipping = $6.40

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This is the way to go. Not sure why more people aren't going this route. I tried the make shift power supply and fan route, but it just didn't work out for me.

-=Jason=-

Sent from my HTC Incredible using Home Brew talk

Edit: I bought a fan off Amazon.com it uses USB for power do your don't need some special 12V power supply.
http://www.amazon.com/dp/B00080G0BK/?tag=skimlinks_replacement-20

Flomaster said:

This is the way to go. Not sure why more people aren't going this route. I tried the make shift power supply and fan route, but it just didn't work out for me.

-=Jason=-

Sent from my HTC Incredible using Home Brew talk

Edit: I bought a fan off Amazon.com it uses USB for power do your don't need some special 12V power supply.
http://www.amazon.com/dp/B00080G0BK/?tag=skimlinks_replacement-20

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I just used bits and bobs I already had laying around except a $4.99 case fan I bought new locally at a shop I drive past daily anyway so no shipping cost. I have substantially more spare 12v power supplies laying around (although I used a multi-voltage power supply I had laying around) than special 5v ones with USB sockets and I don't do my starters in the office with my computer so that is why I didn't go that route.

The important thing is there are more ways to skin this cat then there are cats and everyone should do what works for them.

mredge73 said:

I thought that I would post what I bought today to build my stir plate.

I bought this fan (Comes With Fan Controler!!!)
http://www.newegg.com/Product/Product.aspx?Item=N82E16835200020

$7.99 - $1.59 (Discount Code BTEKAJA22) + Free Shipping = $6.40

Click to expand...

so do you just pick up a 12v power adapter like this one and hard wire that puppy? http://www.newegg.com/Product/Product.aspx?Item=N82E16812125018

camiller said:

I just used bits and bobs I already had laying around except a $4.99 case fan I bought new locally at a shop I drive past daily anyway so no shipping cost. I have substantially more spare 12v power supplies laying around (although I used a multi-voltage power supply I had laying around) than special 5v ones with USB sockets and I don't do my starters in the office with my computer so that is why I didn't go that route.

The important thing is there are more ways to skin this cat then there are cats and everyone should do what works for them.

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I guess I wasn't as fortunate. The fans I had on hand burnt out, none of my power supplies would turn the fans I had. When I did find a combo that worked the slowest setting was still way to fast

-=Jason=-

Sent from my HTC Incredible using Home Brew Talk

Just built one today. OP saved me about $110 from what the LHBS was selling them at.

I did have to monkey with the magnets a bit. Ended up using both the magnets I salvaged from the old HDD.

I think speed can be almost anything so long as the magnets are strong enough. My old plate would go full speed once I got it balanced. It was 2900ish rpm in the case so with weight it was probably 2500+. My current had an external rpm control but the base fan is slower (2400rpm) which is fine cause I didn't have anymore scsi drive magnets. It will turn full speed (shows 1920-1960ish) but I still don't have it remotely balanced. It will also turn without throwing containers up to about 7/16ths thick without losing the bar which is good because the fan doesn't seem to be adjustable.

for a sub $10 box people should look at lock cash boxes. They are metal so they can hold a good amount of weight, are big enough to have lots of room to mess around in and are cheap.

http://www.sears.com/shc/s/p_10153_...19x00001a&ci_src=14110944&ci_sku=SPM241831844

ekjohns said:

They are metal so they can hold a good amount of weight

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Metal top and magnets, probably not a good combo. But hey, maybe it's aluminum (doubt it).

I was thinking along the lines of cutting out a hole over the fan to allow easy access to the magnets if you need to adjust spacing and height. Then there will not me metal over the magnet

10-4 wth the part list anyone can do this! Thanks to the Builder and HBT!

ekjohns said:

I was thinking along the lines of cutting out a hole over the fan to allow easy access to the magnets if you need to adjust spacing and height. Then there will not me metal over the magnet

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I have a hole in my lid do I could raise the fan up higher

-=Jason=-

Sent from my HTC Incredible using Home Brew Talk

Just got my 1000ml flask and stir bar today. The stir plate works great. Thanks for the excellant tutorial.

just finished my stirplate. I have a 1" stirbar and 2000mL flask. After tinkering w/the magnets (how do magnets work?!?!?!? ) I got it to work flawlessly. brings a strong vortex all the way down on a full flask.

I used home depot magnets for 2.19 a two pack. rectangle shape.

Sounds like you got it right. If serious about the magnet question (sorry I don't do sarcasm early) the magnetics place people have linked to as a good place to buy magnets (k&j magnetics or something like that) throughout the thread has some good write-ups about the poles and fields. You want north on one side, south on the other. It's why hd magnets can be hard to use as their not all magnetized axially.

www.magnet4less.com is also a good place for magnets, they have a large variety of shapes and sizes. I use the 1/8" x 3/8" button style magnets, 2 for each stir plate.

+1 to Accidic, it's important to get ones that are polarized axially. In my case, through the 1/8" dimension.

Just finished my stirplate and it works awesome. Well kinda I need to source a higher voltage power supply, I started with 4V then stepped to 5V which works but I would like more power. Stupid me cleaned out my tangled mess of old power cords about a month ago.

But that being said Thanx a bunch to the OP really saved a lot of money.