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

Chefencore said:

Think I fried it. Plug is hot and it's not working. Guess I need a smaller voltage plug after all. Darn.

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If it is getting hot there is probably a short in your wiring. Check everything. I didn't bother with a switch, just plug it in when i want it to go and unplug to stop.

Edit: Also, you may have problems with the 2" stir bar using hard drive magnets. Remember, HD magnets do not have the poles on the faces but are instead polarized radially. Most of the successful builds using HD magnets use a 1" stir bar which seems to balance in the magnetic field better. If you must use the 2" bar I'd suggest the small disc magnets that are polarized on their faces. I saw some at walmart in a three pack with the office supplies if that helps.

Ok so mine works great with a flat bottom vessel. I got my flask today and it just throws the bar right away. I have a1 and 2 inch bar. Both throw. I have 4 rare earth magnets two per side. Any suggestions? Adds more magnets?

Ok so mine works great with a flat bottom vessel. I got my flask today and they have a convex bottom so it just throws the bar right away. I have a1 and 2 inch bar. Both throw. I have 4 rare earth magnets two per side. Any suggestions? Adds more magnets?

Ok so mine works great with a flat bottom vessel. I got my flask today and they have a convex bottom so it just throws the bar right away. I have a1 and 2 inch bar. Both throw. I have 4 rare earth magnets two per side. Any suggestions? Add more magnets?

wegz15 said:

Ok so mine works great with a flat bottom vessel. I got my flask today and it just throws the bar right away. I have a1 and 2 inch bar. Both throw. I have 4 rare earth magnets two per side. Any suggestions? Adds more magnets?

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Well, if it isn't working with the convex bottom it's likely that the stir bar has become too far from the magnet. You could try raising the fan assembly closer to the top of the case, or adding more magnets.

Edit: didn't see your pic at first. Because of the way the magnets are paired up I surprised it runs stably. With two north polls up at one end and two south pols up at the other I could see the bar getting drawn off center one way or the other. Try putting a stacked pair at either end.

I would also suggest stacked pairs at either end. Also, you posted 3 times in 5 minutes with the same question. Could you delete two of them please?

wegz15 said:

Ok so mine works great with a flat bottom vessel. I got my flask today and they have a convex bottom so it just throws the bar right away. I have a1 and 2 inch bar. Both throw. I have 4 rare earth magnets two per side. Any suggestions? Add more magnets?

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I like the use of the lid from a container of frozen juice.

it could also be weak magnets. There are several strengths of magnets, and if the ones you bought didnt come with a n rating they are probably not the strongest. I am planning on buying some super strong n42 neodyniums from online here soon. The place I am looking at is cheap but absolutly RAPE you on shipping. I will probably order a bunch and resell them at a good price on here. Would people be interested in some at say $5 shipped/ pair. These suckers will be very strong and will probably make it near impossible to toss the magnet (each one is smaller than a dime and has a pull force of 13 lbs!)

edit: Also wanted to mention that these will be easier to balance than the hardrive magnets that are cuvered. If i get enough people interested ill place the order. PM me if you want to get in on this

check eBay as well

i got these for under $5 shipped

http://cgi.ebay.com/10-Neodymium-di...544?pt=LH_DefaultDomain_0&hash=item45fa74c700

yeah those are the weaker n35s. for the same $5 if people are interested i can get n42s. you wont get as many but wont have to worry about stacking a bunch up or having to get the fan super close to the top of the box

stacking helped me adjust the height properly

there are tons of options, just pointing out another source

good point

i was thinking about trying to pull a vortex on my brew pot after boil to help circulate the wort around the IC which is what got me looking at powerful magnets. My plan is to build a base for the kettle with a hole cut in the center. I would then mount a fan with a speed controler with those powerful magnets. I noticed that if I stir the wort as it cools non-stop as opposed to every few min, i can cool 5 gal in under 10min opposed to 20-30. Plus i wont have to stand there and stir for 10 min BORING!

Finished my second stirplate and thought I would post pics of both. Small uses 1 inch bar and is for yeast starters. The bigger uses a 2 inch bar and is for Mead. The glass is 2 gallon from Walmart for $10 I use for mead batches. The plan is to continuously stir the mead for the first week or so.

camiller said:

Because of the way the magnets are paired up I surprised it runs stably. With two north polls up at one end and two south pols up at the other I could see the bar getting drawn off center one way or the other. Try putting a stacked pair at either end.

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So what you're saying is use a stack of say two magnets on only one side of the fan?

Wouldn't that be unbalanced and cause vibration?

Also, I don't know how to delete my other over posts. My hbt app was acting up.

no you will have a stack of 2 magnets on each side of the fan. from your pic it looks likes you have 2 magnets on each side but they are side by side not stacked

Ok. I originally did it that way to use either a 1"or 2" bar. I guess I could buy more magnets and do two double stacks.

Finished mine up a couple of days ago. Waiting on stir bar to arrive for proper test. A few things:

The switch design definitely calls for 1/4" disconnects now. At your local hardware store, .250 22-18 or 22-16 AWG Terminal Insulated Disconnects is probably what you should be looking for.

My 5v power supply wires were very thin(greater than 20 gauge) and thus hard to strip. I found it much easier to score the casing and then pull it off with a pair of pliers(doing so gently.. squeeze too hard and you'll likely tear the wire).

And, uh, as one might imagine crimping the disconnects onto the wire with a pair of vice grips is much easier than with pliers.

Also, on both sides of the power supply hole I wrapped the power supply cord with electrical tape to prevent it from being pulled out accidentally.

Grip-It Shelf and Drawer Liner costs like $3 a roll. Invest in some. A square of it placed atop your stir plate should keep the flask from sliding around/being knocked off inadvertently.


Thanks for the write-up.

Works great. One inch stir bar is thrown at higher RPM. Guess I'll try a 1.5" bar. If that doesn't help, I'll see about adding another hdd magnet.

organ said:

Works great. One inch stir bar is thrown at higher RPM. Guess I'll try a 1.5" bar. If that doesn't help, I'll see about adding another hdd magnet.

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Or run at a lower RPM? Seems like somewhere along the line I read some babble about shearing effects...detrimental to yeast...bla bla bla. Yeah, it looks cool to pull a vortex to the bottom of a 6 gallon carboy, but totally unnecessary and possibly harmful. If you are pulling a dimple in the surface it's running fast enough to keep the yeast suspended.

wegz15 said:

So what you're saying is use a stack of say two magnets on only one side of the fan?

Wouldn't that be unbalanced and cause vibration?

Also, I don't know how to delete my other over posts. My hbt app was acting up.

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ekjohns said:

no you will have a stack of 2 magnets on each side of the fan. from your pic it looks likes you have 2 magnets on each side but they are side by side not stacked

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What ekjohns said. Basically the two magnets next to each other (no mater how many high) are fighting over the end of the stir bar. in my compleatly un-informed and unscientific opinion.

I finally finished my home made stir plate. A couple of changes:

1. I picked up a sweet cigar box for $1 at my local cigar shop. There's something very right about using a cigar box for brewing equipment. Sort of like the Most Interesting Man in the World's home made stir plate.

2. I got real rare earth magnets from a hobby shop. They were WAY easier to deal with than the HD magnets, and allowed me to use a 2" stir bar.

3. I got a 2" bar with a pivot ring in the center. They run quieter, and are more tolerant of non-perfectly flat surfaces.

I'm pretty happy with how she's running. My yeast starters are immeasurably better in quality. I usually get good vigorous fermentation in less than 6 hours!! :rockin:

A couple of shots:





And the requisite YouTube video:



Thanks guys!!

William

Hard drive magnet & 2" stir bar(with pivot ring). I actually lost my 1" bar and one of the other members of the club loaned me this one.


I did spend quite an amount of time getting the HD magnet lined up and centered. In the photo it is running at 3v but I had it running as high as 9v which pulled a pretty good vortex.

I just got my setup made, had some difficulty with my stir bar (1-3/8") staying in the center of the flask.
It wanted to spin off center quickly. I think I may try a 2" stir bar at some point if anyone thinks it might help?

camiller said:

Or run at a lower RPM? Seems like somewhere along the line I read some babble about shearing effects...detrimental to yeast...bla bla bla. Yeah, it looks cool to pull a vortex to the bottom of a 6 gallon carboy, but totally unnecessary and possibly harmful. If you are pulling a dimple in the surface it's running fast enough to keep the yeast suspended.

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I'm not after a large vortex; at full throttle my fan wont form one anyway(although it may with a larger stir bar). I just wanna be certain that the bar isn't thrown five hours into an over-night stir.

cheffriz said:

Need some assistance with this

not sure how to get the magnets off the larger pieces of metal

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Put the metal bracket into a vise and stick a screwdriver at the base of the magnet. The screwdriver may require gentle persuasion with a few hammer taps. :cross:

For those of you that are saying that your bar is spinning off center, I'd suggest fine tuning the centering of your magnet until it spins in the center of your enclosure or the desired spot.

hs0656 said:

Put the metal bracket into a vise and stick a screwdriver at the base of the magnet. The screwdriver may require gentle persuasion with a few hammer taps. :cross:

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I've been able to bend the back plate enough to fit any flathead behind the magnet and pry it off with very little force. The magnets are stronger than the glue holding them on, so they don't bend with the backplate.

Anthony_Lopez said:

For those of you that are saying that your bar is spinning off center, I'd suggest fine tuning the centering of your magnet until it spins in the center of your enclosure or the desired spot.

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the problem is not so much the position of the magnet its the physics behind it. A nice stir bar is magnitized through the length giving it a N and S poll on each end. Hardrive magnets are polarized through the thickness giving each face a N and S poll. If you are using a small stir bar this is not a problem cause the hardrive magnet is large enough to keep it centered. However, If you are using a larger stir bar the bar spins off axis and gets tossed at very low speeds. The best was to make one is either to get a bar magnet polarized through the length similar to the stir bar or to buy small magnets that you can put on either side (one with N facing up and the other with S facing up) with a space in the middle. I have both harddrive magnets and small cirlce magnets that I have tested with 1", 1.5", 2", 3". The small circle magnets work well with all 4. The harddrive magents works perfect with the 1" so/so with the 1.5", okay at slow speed with 2" and not at all with the 3".

as a quick reference to people building these from now on follow this chart depending on what you already have or how much you are will to spend:

Magent type ............... stir bar size
1 hardrive magent ....... 1"
circle magnets ........... 1-2"
bar magnets* ............ 1-3"

*Bar magnets needs to be polarized through length and matching the length to the stir bar is ideal

hope this helps

ekjohns said:

Hardrive magnets are polarized through the thickness giving each face a N and S poll.

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NO, NO, NO, NO, NO!

Hard Drive Magnets are not polarized through the face, they are polarized lengthwise.



like this only flatter:



images from: http://www.kjmagnetics.com/magdir.asp

Edit: And for what it is worth, I have had no problem spinning a 2-inch bar once i "really" got the HD magnet spinning at its true magnetic center.

ive tested mine and they are not polarized like that. If they were, the one side of the stir bar would attract to the green and repel the red. However, all my stir bars attract to green and red side of the magnet with one side of the bar and repel will the other.

organ said:

I'm not after a large vortex; at full throttle my fan wont form one anyway(although it may with a larger stir bar). I just wanna be certain that the bar isn't thrown five hours into an over-night stir.

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If it runs fine for 5 hours and then throws the stir bar something else is the problem. When I had that happen it was because I assumed that the magnetic force of the magnet was sufficient to hold it to the washer glued to the fan. In reality the magnet was ever so slightly moving over time. I had set the starter stirring one evening and the next day my wife call me at work about lunch time and said it wasn't stirring any more.

ekjohns said:

ive tested mine and they are not polarized like that. If they were, the one side of the stir bar would attract to the green and repel the red. However, all my stir bars attract to green and red side of the magnet with one side of the bar and repel will the other.

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so like this?


image borrowed from http://www.kjmagnetics.com/magdir.asp

Because with mine one end of the stir bar will attract one end of the HD magnet and repel the other.

Edit: In fact I would expect my stir bar to want to stand up on end if what you are describing was the case with my magnet.

I built mine using a piece of scrap wood and some parts from Radio Shack and it works really good...

I built one today. Waiting for my flask and stir bar. I'll post back when they arrive.

Here is mine, based on your original design.

can you do this without the switch and just the rheostat? i don't really want an on off switch... i'll just unplug the power supply.

Apoxbrew said:

can you do this without the switch and just the rheostat? i don't really want an on off switch... i'll just unplug the power supply.

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That's how I do it

okay... so i've got mine wired up and working. problem now is that i can't figure out how to keep the bar from getting thrown to the outside. no matter what i try i can't keep the stir bar in the middle of the flask and spinning, it just gets thrown to the outside. any ideas?

Apoxbrew said:

okay... so i've got mine wired up and working. problem now is that i can't figure out how to keep the bar from getting thrown to the outside. no matter what i try i can't keep the stir bar in the middle of the flask and spinning, it just gets thrown to the outside. any ideas?

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Less power...or a different size stir bar.