DieterVonBrauhaus
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Does a stir plate require only rare earth magnets? Can't I use fridge magnets and glue them to the fan?
Stir Plate question
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joeybeer
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Even with rare earth magnets from a HDD are barely strong enough.. The magnets on a fridge are way too heavy and way too weak.. I battled mine for about a year, and it drove me crazy.. Just got a Black MAXX and it does everything I want it to. Even as an avid DIYer, this is one thing I just couldn't get to work right.
Bensiff
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Yes you need rare earth magnets, buy some online though, mine are 1/4" and I wish they were a bit larger as I occasion to through the stir bar on startup. I'm on my second build as my first one got some blowoff onto the circuit board and rheostat which killed the circutry. It takes a little playing with distances and speeds, but you can get it down.
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DieterVonBrauhaus
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you think Radio Shack has them?
camiller
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probably, also harbor freight, wal-mart, ace hardware, probably hobby stores.
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DieterVonBrauhaus
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Thanks fellow brewers
you can also use hard drive magnet if you can get a hand on them.
Steelers77
Vendor
If you have a hobby lobby near you I think they have them.
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DieterVonBrauhaus
Well-Known Member
NO extra HD's as they are all in my PC, I will try Radio Shack. Also I am using as a power source a HO scale model transformer works well with the fan!!
thats a great idea...
You can buy hundreds of small ones online from China for a few dollars... They work well and I think they are easier to line up than the oddly-shaped HDD mags.
Radio Shack does not carry rare earth magnets, I checked 2 days ago. Lowes does not either.
DarkPhyre
Well-Known Member
I got mine from Home Depot. They are NOT rare earth and work better then the rare earth ones I got from radio shack. about 100 times better. I got it to work third try and at full speed. I pull a 1 inch vortex on a full 2L flask.
StirStarters
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A good source for rare earth (neodymium) magnets is www.magnet4less.com
I use the ND021 button style magnets for the stir plates I build, they are 1/8" x 3/8"
I use the ND021 button style magnets for the stir plates I build, they are 1/8" x 3/8"
camiller
Well-Known Member
https://www.radioshack.com/product/index.jsp?productId=2102642
emphasis addedRadio Shack said:
But there are plenty of lower cost alternatives.
CrazedArmadillo
Active Member
I bought these rare earth magnets at a local True Value hardware store
http://www.hardwareandtools.com/Master-Magnetics-07046-Super-Neodymium-Magnet-Discs-7380702.html
They are extremely strong...I have a 2" stir bar, and if I stacked two magnets on each end, i was able to run my stir plate perfectly at full speed without throwing the bar even once. The trick is to make sure you space the magnets the proper distance for your stir bar. To determine this distance, just stick one magnet to each end of the stir bar...they will position themselves with the appropriate spacing between them. For optimal results (ie no thrown stir bars) the magnets should be this far apart on top of your fan.
http://www.hardwareandtools.com/Master-Magnetics-07046-Super-Neodymium-Magnet-Discs-7380702.html
They are extremely strong...I have a 2" stir bar, and if I stacked two magnets on each end, i was able to run my stir plate perfectly at full speed without throwing the bar even once. The trick is to make sure you space the magnets the proper distance for your stir bar. To determine this distance, just stick one magnet to each end of the stir bar...they will position themselves with the appropriate spacing between them. For optimal results (ie no thrown stir bars) the magnets should be this far apart on top of your fan.
The Radio Shack in my town does not have them, I was looking for some for a stir plate and asked. All they had on the wall was ceramic and the employee said that was all that was available. I knew I should not have listened to the employee.
Maybe if I offered a trade of beer for them he would have found some for me.
CrazedArmadillo
Active Member
Those Radio Shack magnets are only 3/16" diameter...seems pretty small, and kind of expensive since you only get two in the package.
thargrav
Well-Known Member
If you are curious about the Black MAXX Stir Plate you can read more here:
http://www.stir-plate.com/BlackMAXX.htm
The best place to buy neodynium magnets is from here:
http://www.kjmagnetics.com/
joeybeer said:
Agree with everything here.
Fridge magnets wouldn't even have a noticeable pull on the stir-bar, much less be able to keep it spinning.
Hard drive magnets are mediocre, and much better ones can be bought extremely cheaply.
The Black Maxx stirplate is absolutely amazing.
camiller
Well-Known Member
I have had no problem whatsoever using a single hard drive magnet with a ~1" stir bar. I've also used it with a ~2" bar but it took a lot of tweaking to get it balanced. My build thread is in my sig.
The trick (if there is one) is to get the center of the magnetic field centered on the fan. Due to the kidney shape of a hard drive magnet, it might not be where you expect it.
thargrav
Well-Known Member
Hard drive magners are really a shot in the dark because the hard drive you break open may or may not have magnets suitable for a stir plate. If you do decide to go the hard drive magnet route you need to take apart the oldest drive you can because over the years the head, armature & magnets have been getting smaller to save weight & speed up the drive.
How are they getting them to work? None of the ones I looked at worked right. Assuming the stir plate works as all, the most common problem I've seen is the stir plate would only spin at slow speeds. Once you picked up speed it would throw the magnet every time.
phoenixs4r
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I got some 20lb magnets off of a cabinet repair section at ace. They are to keep cabinet doors close. Work great.
Before, we used magnets we busted out of the fish tank scrubbers. You know the ones that have a scrubby pad on them and u use the force of the magnet to clean your tank? We got them to clean the carboy but they didn't fit down the neck so we smashed them and took the magnets out, lol.
Before, we used magnets we busted out of the fish tank scrubbers. You know the ones that have a scrubby pad on them and u use the force of the magnet to clean your tank? We got them to clean the carboy but they didn't fit down the neck so we smashed them and took the magnets out, lol.
thargrav
Well-Known Member
The best place to buy neodynium magnets is from here:
http://www.kjmagnetics.com/
http://www.kjmagnetics.com/
I just built two plates using HD magnets and 2 in bars. They worked good with water. Wort is a different animal.
I had a starter going for two days, and my wife called me at work today to tell me "your beer thing is making a loud funny noise".
Please turn it off honey... "I already did, how much longer does this have to be in the kitchen???"
I'll move it today honey.
Luckily the starter is done, but it threw the bar on the lowest speed.
I may end up buying one.
I had a starter going for two days, and my wife called me at work today to tell me "your beer thing is making a loud funny noise".
Please turn it off honey... "I already did, how much longer does this have to be in the kitchen???"
I'll move it today honey.
Luckily the starter is done, but it threw the bar on the lowest speed.
I may end up buying one.
I have only made one starter, and this happened with my stir plate that I made with HD magnets. However, I put two carpenter pencils on top to raise the flask and everything worked fine. I did order some of the above recommended magnets and will use those for my next starter.
camiller
Well-Known Member
The only time I had this problem was due to the HD magnet shifting (At first I thought it would be strong enough to hold itself to the washer without glue. Once I re-centered and glued it I never had this problem again.
I bought the magnets from harbor freight, and had to make larger spacers to move the fan as close to the top of the stir plate as the bolts would let me, then hot glued 3 magnets on top of each other to make the rest of the gap. Works great with water on the lowest setting, but I am yet to try with wort. Will see how it goes.
thargrav
Well-Known Member
I finally took apart a failed hard drive and did some testing and at least with the one I took apart, can tell you why the hard drive magnet won't work well.
The hard drive magnets (there were two in the drive, opposite each other) were not rectangular magnets, they were made into a arc. The magnets seemed strong enough but because of the way they are made you can't center the N and S poles directly across from each other without throwing everything off balance. When mounted with the N and S poles directly across from each other, most of the magnet weight was to one side of center and this caused a serious vibration problem kind of like your cell phone buzzer but 10 times worse.
Then when I mounted the magnet so the weight was balanced the N and S poles wanted to pull the stir bar off center towards the N and S poles. The stir bar wasn't pulled far off center but it was enough to cause the stirbar to throw at any speed but the lowest setting.
Either of these issues will cause your stir plate to throw the stir bar. You stir bar has to spin centered above the motor with as little as possible to pull it off center.
It seems that hard drive magnets would work great if they were made into a straight bar. Has anyone taken a hard drive apart with magnets made this way? If so you should share the make & model number with the list.
I made mine with hard drive magnets and old power converters from ?? I glued the magnet on the fan and it quickly came loose from the glue. I now have it holding to the fan by its own magnetism.
The first power converter spun the fan too fast and would throw the stir-bar. I then used one from an old answering machine and it works like a charm. I am using a 1" stir-bar. I put a rubber o-ring in the center to make it spin better.
The first power converter spun the fan too fast and would throw the stir-bar. I then used one from an old answering machine and it works like a charm. I am using a 1" stir-bar. I put a rubber o-ring in the center to make it spin better.
camiller
Well-Known Member
I made mine with a single hard drive magnet and it works well at any speed except the very highest (any voltage from 3v-9v is OK, 12v was to fast, 1.5v and the fan stalls. My power supply is variable from 1.5v to 12v in 1.5v steps except there is no 10.5v). As you said, you have to align the magnetic field across the diameter of the fan and not the weight. With mine there is no significant vibration, although I did use a fender washer on the fan which gives the fan more rotating mass than without it so the amount of imbalance due to the uneven distribution of the magnet's weight is comparatively small. For my magnet the center of mass and the magnetic center are within perhaps 1/16" inch anyway, so there was not a huge imbalance to start with.
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