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

[TommyBoy]

My bar won't spin fast enough to get a vortex to the bottom. I am using a 1" bar and a 1.5" bar. I have a 9v power supply and the computer fan/hard drive magnet setup. I do not know if the power of the magnet is pulling up on the fan hard when the flask and bar are on the stirrer and the friction is slowing the bar or what. It spins fast when the bar is in an empty flask so maybe I just have a weak fan?

I would like some opinions before I open it up and solder another fan in.

 

[Hang Glider]

You don't need a vortex to the bottom, you're just trying to keep the yeast in suspension -
However, some folks here (myself included) have spaced the magnet off the fan some. The magnet definitely interferes with the motor, and depending on magnet and motor, your motor may overcome that or not.

Mine wouldn't spin slowly until I moved the magnet 3/4" off the hub. It was all or nothing. Now, I can slowly crank up the speed and get a nice small vortex, or work it slowly up the scale and get a pretty good sized one.

 

[Anthony_Lopez]

Thanks to everyone keeping this alive and posting about their successes or problems... Someone in my homebrew club pulled one out of his gear tool box, and said he found this thread here, and built it according to specs. He had no clue that it was me...

 

[TommyBoy]

You don't need a vortex to the bottom, you're just trying to keep the yeast in suspension -

Doesn't the vortex help aerate the starter?

 

[Arkador]

Hmm, will need to stop at Radioshack after work. I have most of these parts already. I bet i can get a stirbar at my LHBS next time I am there.

 

[the_merlin]

My bar won't spin fast enough to get a vortex to the bottom.

You need to drink 12+ beers to get your bar to spin.

 

[Catt22]

Doesn't the vortex help aerate the starter?

It probably does, but it isn't necessary at all to have a vortex. A sufficient gas exchange will occur at the wort surface. Stirring the wort keeps the wort "turning over" so that fresh wort will be exposed to the surface continuously. Stirring also keeps the yeast in suspension where the food is more accessible. I'm pretty sure that a vortex won't do any harm, but it isn't the holy grail either.

 

[Schnitzengiggle]

I just used mine for the first time last week, made two starters, I am able to get a vortex about 1/2 way down my growler for a 1 liter starter with a 2" stirbar.

I am using a 6v cell phone charger, but a buddy of mine has a bunch of old cordless phone chargers one is 9v and another is 10.5v.

I was wondering if using one of these would give my fan a little more power to pull the vortex down a bit further?

Also, if wattage is listed on the charger does that make a difference?

I think the 10.5v charger states 14 watts, and the 9v might be like 2 watts, I'm not certain, my cell phone charger that I am using now is .5 watt.

Can higher wattages burn out my fan if the charger is 12v or under?

 

[Catt22]

The wattage rating is probably for max output. IOW, the transformer is rated at 1.3 amps max draw at 10.5 volts. Don't confuse the power consumption rating that is usually listed on the transformer too. This will typically be a very low number like the 0.5 watts one that you mentioned.

So, I would ignore the wattage ratings and focus on the voltage only. So long as you do not exceed the 12 v fan rating you should be safe and not burn it out.

Forget the vortex. So long as you are stirring the wort it will work perfectly with or without a vortex. The bes thing you could do for an improvement would be to get a larger 2 liter flask. IMO, a 1,000 ml flask is pretty much a waste of time and effort. The one liter flasks just don't have enough wort to support a large yeast population growth. It's better than nothing, of course, but bigger would be better in this case.

 

[marubozo]

I don't really have anything meaningful to add, but +1000 for the hard drive magnets. I tried a setup with just two little round magnets on the fan and while I could get it to work, it was very sensitive and would throw the bar regularly. So I took a hammer to my old desktop computer and salvaged one of the hard drive magnets and it worked like a charm.

Top speed and no throwing the bar at all and it can pull a vortex down all the way in 2L without a problem. After my build I was about ready to throw everything out the window but a better magnet basically solved all of my problems.

 

[Catt22]

I gave up entirely on using the hard drive magnets. Far too much hassle to remove them from the HD and also too much hassle trying to position them properly. I now use store bought rare earth magnets. They are not at all expensive and they are much easier to position for more precise balance. The magnets cost about $2.00 each including shipping. I like the 1/4" x 1" size and I mount them vertically. I've built quite a few stir plates for my brewing friends and they're all working quite well.

 

[Donner]

i may have missed it, but is it possible to use a smaller computer fan? A buddy gave me two fans that are smaller than the ones i've seen people using here and i'm curious if they will work for this project. I'm not one that makes huge starters and just want something that will help along the process.

 

[Yunus]

i may have missed it, but is it possible to use a smaller computer fan? A buddy gave me two fans that are smaller than the ones i've seen people using here and i'm curious if they will work for this project. I'm not one that makes huge starters and just want something that will help along the process.

You might be able to use a smaller fan. But it will be putting the same load on a smaller motor so it might not last as long and you will probably need a very small stir bar unless you put a plate on top of the fan to spread out the magnets.

 

[Atticmonkey]

What size stir bars does everyone use? I got a couple of 2" bars for a 1000L flask and it just wont hold the bar and keeps throwing it off the center. Is the bar maybe to big? Also has everyone had better luck with the pivot rings or without?

 

[johnnyc]

For stirbar size I think people have had the best success with something no bigger than your magnet itself. I'm using a 1.5" with a hard drive magnet and it works well.

 

[Thumper]

I just wanted to say thanks for doing this thread with such great instructions and photos. My 14 year old boy just finished this last night. He is going to use it in his electricty project for 4-H, and then I get it for my use. We spent Sunday afternoon building it, and then a couple of hours last night getting the magnet placement and proper spacing set correctly. We are getting a full vortex with the bubbles just touching the bottom of a full 1 liter flask. I can't wait to the see the judge's face when he tells him what this will be used for. I am making sure he knows that these stir plates have labortory uses also. I will update after it gets judged. He is putting together a cost sheet today and I am intrested in seeing the final total.

Thanks again,

 

[json2001]

Thanks for the build notes. I soldered mine up yesterday. Spins the fan great!

I used a 9v power supply I found for an old piece of hardware and a 120mm case fan I had wasting space. But I have yet to glue my washer on. Namely because I haven't gotten my flask or stir bar yet so I'll just wait to test it.

I am planning on super gluing the washer on. To align it I have turned the fan on and used a pencil to inscribe circles that SHOULD be equidistant from the center. So hopefully I'll just line up the inner circle of the washer with one my my circles and have to do minimal adjustment while gluing it up.

Here are some pictures of my proposed method of alignment for the washer as well as the HDD magnets I am planning to use. I also noticed my hdd magnets came as 4, not as one bar. So hopefully this system with them spread out will work?





Thanks again for the thread. Good stuff.

 

[Hang Glider]

json2001,
looks good - I actually broke my 1-piece hard drive magnet in half and re-glued it (epoxy) to my fan much like yours looks. Spin bar stays put much better. So, you set up should be fine.
These Flasks are great, love the cork coating for sure grip and cool right off the burner.

 

[json2001]

json2001,
looks good - I actually broke my 1-piece hard drive magnet in half and re-glued it (epoxy) to my fan much like yours looks. Spin bar stays put much better. So, you set up should be fine.
These Flasks are great, love the cork coating for sure grip and cool right off the burner.

Oh very cool. I'm going to be ordering some ingredients and some other odds and ends from AHS soon. So I was considering just getting their yeast starter kit. Seems like I should get the 2L flask?

Thanks for the feedback!

 

[avibayer]

I just built one yesterday using a three inch fan from an old computer, the magnets from the HD, and the items listed in the first post. Used an old phone charger (6V) for power source. waiting for my flask and stirbar, but tried the plate out with a glass of water and one of the HD magnets, with not much luck.

I am totally new to building, and quickly slapped this together. The magnet jumps around in the glass, the stirplate rattles around a lot, and the vortex does not exist.

was thinking about putting both magnets on the washer on the fan, though i don't understand what everyone means by spacing them, and balancing the weight of the two magnets with smaller washers to prevent the rattling. Does that make sense/sound right?

By the way, thanks for a truly amazing and helpful thread,

cheers

 

[Hang Glider]

avibayer - waiting for flask and stirbar -
while many types of magnets exist for the underside with the fan, I don't think you'll be able to test it without a stirbar - that plastic casing is somewhat essential in getting things to spin. As far as the spacing - two meanings exist - 1) look at post 287 - spaced apart, and 2) height off the fan motor. Some of the stronger magnets interfere with the motor spinning (it's essentially a type of electromagnet in itself), so raising the magnet away from the hub of the motor often helps. Good luck, I think you'll probably be pleased when your stirbar arrives.

 

[avibayer]

Thanks hang glider

 

[Homercidal]

I'm building my second one. The first worked out so well, that I'm building one for a friend. I got lots of HDD magnets and a few old printer selection boxes that are obsolete now that network print servers come in every printer sold.

I find the HDD magnets work very well, and even though I can pull a vortex down to nearly the bottom with a 1" stirbar, I never run it that fast. I just turn it on low and let the thing keep the yeast mixed up.

The results have been just as good as cranking it.

 

[c0bra]

So think I've got mine wired up right, however it doesn't seem like the fan has much variability at all through the rheostat. The only way I can tell is to tape the magnet to the fan and listen to frequency of the vibrations it causes in the case. It seems a bit faster with the rheostat dialed all the up vs all the way down, but it's not much at all.

I saw elsewhere in the thread that some people were using a resistor. Would doing so help my problem? Any particular rating (or whatever you call it) to use?

Unfortunately I don't have my stir bar so I can't see how well this current setup will work.

 

[avibayer]

stir bar came, and after playing with the magnets for an hour, i was able to get a vortex down to the bottom. my yeast were super happy. I used a washer with a hole in the middle that was so big, the HD magnets wouldn't rest across the middle. So i glued a piece of metal across the gap, put the two HD magnets on it, and it did the trick.

the only issue i have, is i have to make sure the stir bar is in the middle of the flask to get it to spin properly, and with murky starters that can be tricky. but its kinda fun too. finding the sweet spot.

thanks for an awesome thread, helping non-engineers like me build a stir plate on the cheap.
cheers

 

[inspector13]

Great instructions. I was finished in about 35 minutes and it works great.

Thanks,
Wade

 

[Anthony_Lopez]

Well, I'm back from a long tournament Bass fishing season. I'm glad to see my thread has continued to stay on the first page... 30 pages!?!?

 

[quixand]

In case anyone cares, 64-3134 is not the right part numbers for quick disconnects that fit that rocker switch. So you don't have to make another trip like I did, get 64-4040's. You need 1/4" disconnects for the rocker switch.

In other news, I have a 120mm pc fan in mine, which I cut all the blades off with a dremel, and it doesn't seem like it spins fast enough to make a vortex to the bottom. Do I need to use both of the HD magnets? I can't tell if I can't get a vortex to the bottom because the fan speed isn't fast enough, or I don't have enough magnet force.

 

[Anthony_Lopez]

In case anyone cares, 64-3134 is not the right part numbers for quick disconnects that fit that rocker switch. So you don't have to make another trip like I did, get 64-4040's. You need 1/4" disconnects for the rocker switch.

Unless they have changed the design of the rocker switch, the 3/16 disconnects should work. I built 3 stirplates for club members following my own "how to thread" to make sure I didn't miss anything or mess up the instructions. I'll take a run down to the SHACK today and take a look at what they are stocking. 3/16" vs. 1/4" disconnects shouldn't make much of a difference, however I will verify and edit the thread for now.

Thanks for the input!

 

[quixand]

Unless they have changed the design of the rocker switch, the 3/16 disconnects should work. I built 3 stirplates for club members following my own "how to thread" to make sure I didn't miss anything or mess up the instructions. I'll take a run down to the SHACK today and take a look at what they are stocking. 3/16" vs. 1/4" disconnects shouldn't make much of a difference, however I will verify and edit the thread for now.

Thanks for the input!

Well...I can most assuredly tell you the part number of the quick disconnects wouldn't even come close to fitting the part number for that rocker switch.

When I went back later that evening, the part number I picked up was snug, but a perfect fit. Not sure if I got an older switch with the same part number before they went to a smaller size or what...but just wanted people to know to double check at the very least. There may be multiple sizes of the rocker switch part number, with different sized male ends. LOL