My shamelessly cheap $12 DIY stir plate

[PerryS]

thanks for the advice, glad to hear you got yours up and running,, mine will have been on for 48 hours this afternoon, is it alright to jar right after full krausen?

The yeast will tell you when they're done. Usually 3 days.

Generally, the yeast will stop fizzing and floc out when they're done with the wort. Just like beer. Turn off the stir plate, and see if the wort on top begins to clear. May take 6-8 hours. At that point, I cold crash in the fridge, pour off the excess, and get the yeast into a jar.

If the yeast are going to be in the fridge for an extended period, boiled and chilled water helps to keep everybody asleep.

 

[PerryS]

So it seems getting the magnets in the right spot is crucial for this to work without being off balance.......but what about the washer people are gluing to the fan hub?

Center the washer on the fan by feel. Your fingers are amazingly precise.

Same with the magnets. Hold both magnets while feeling for the edge of the fan hub.

Then spin the fan manually and check visually.


It may take a few tries. I had to scrape super glue off the magnets once.

 

[rideincircles]

I stepped my starter up to 2 liters last night and turned the stir plate on for a little while and it was bubbling over with krausen so I turned it off. It still was filled with krausen this morning so I am leaving it off for now and will turn it back on when I get home. I turned it on briefly and it started to bubble like crazy.

Next time I plan on buying some fermcap for it. Is it pretty much standard to use fermcap with every starter? I need to get a 5 liter erlenmeyer, but until then, my 2 liter is near capacity most of the time.

Also, I had two of these that a coworker gave me, but you can get 100 magnets for $7 off amazon if you need any. I plan on getting some more just because they are awesome magnets.

http://www.amazon.com/dp/B0012AUU84/?tag=skimlinks_replacement-20

 

[GNBrews]

How do the speed controllers handle lower speeds? Is it difficult to keep the stir bar from being thrown when you start it up? I tried one of the rheostat kits a while back, and the speed was almost impossible to get dialed-in. It was either off, or running close to full speed and throwing the stir bar.

 

[finsfan]

i have the same fan with built in speed control and the lowest setting works perfect, it can go a little faster but iv left it on the stirplate for 3 days with no throws

 

[finsfan]

i am too, ive heard pretty long tho at least a few years. for under $20 for everything, thats a great investment if it lasts 2 years. normal stirplates online are at least $100

 

[fc36]

At that point, I cold crash in the fridge, pour off the excess, and get the yeast into a jar.

If the yeast are going to be in the fridge for an extended period, boiled and chilled water helps to keep everybody asleep.

I ran my starter for 24 hours and put in the fridge and was wondering why it seemed like so little yeast was in there.

Anyways, tonight I will decant off the liquid and make 2 liters of starter and pitch it on top of my decanted yeast. Then 24-48 more hours on the stirplate cold crash and hopefully make my beer in 3-4 days.

Why are you guys cold crashing starters? Seems like an unnecessary step to stress out the yeast before pitching into a new batch only a couple of days after making the starter. The only reason to cold crash would be prior to long term storage or packaging on a new batch. Dont cold crash starters if you plan to use them that week.

 

[finsfan]

Why are you guys cold crashing starters? Seems like an unnecessary step to stress out the yeast before pitching into a new batch only a couple of days after making the starter. The only reason to cold crash would be prior to long term storage or packaging on a new batch. Dont cold crash starters if you plan to use them that week.

well perryS said that he cold crashes and stores them until he has to brew, then i assume he makes another starter and directly pitches it from there. I do the same thing, when i get a new pack of yeast i make a starter as soon as possible to step up cell count tremendously. If you were to wait a month or two until you made a starter, ud have to step it up multiple times to get the cell count back to where you need it, i also dont think that putting yeast in the fridge stresses them that much. that is how all LHBS and companies keep their yeast, some even freeze them, and they all get good results down the road

 

[Hang Glider]

you can cold-crash them to get the yeast to settle to the bottom, and pour off the excess - then warm them back up to room temps before pitching.

 

[fc36]

well perryS said that he cold crashes and stores them until he has to brew, then i assume he makes another starter and directly pitches it from there. I do the same thing, when i get a new pack of yeast i make a starter as soon as possible to step up cell count tremendously. If you were to wait a month or two until you made a starter, ud have to step it up multiple times to get the cell count back to where you need it, i also dont think that putting yeast in the fridge stresses them that much. that is how all LHBS and companies keep their yeast, some even freeze them, and they all get good results down the road

I know how they store yeast and like I said in my original reply, I can understand it if you're doing long term storage. Regardless though, if you're going to pitch within a week, no need to cold crash. 1-2L of 1.040 LME or DME starter and a whole **** load of yeast will not change the flavor of your beer at all unless you're pitching into something like a Berlinner Weiss or other super thin beer.

Edit: This is coming from my perspective as a person who typically either buys yeast the same week as a brew day or making a starter from my stock of slants or isolated strain petri dishes.

 

[PerryS]

Regardless though, if you're going to pitch within a week, no need to cold crash.

True enough.

My considerations:

1. The spent wort is rather sour, and can affect the taste if it's pitched with the yeast. Cold crashing settles the yeast so I can dump the sour wort.
2. I don't want to leave a flask on the counter-top and possibly get contaminated - I have kids and cats and limited counter space.
3. I can't predict when I'm going to brew my next batch. My weekend could suddenly fill up.
4. Cold crashing does not seem to affect viability. In fact, it slows down the yeast's metabolism so it theoretically lasts longer.

The great thing about home brewing is that you get to decide how to run your brewery. Cheers!

 

[PerryS]

Currently building a 1.5L starter with the spare-parts DIY stir plate. Started with harvested 1084 that has been patiently waiting for 3 months. It has been spinning for two days, and is now at full krausen.

It's probably poor netiquette to quote yourself, but wanted to report the conclusion of the farming operation.

The krausen subsided, and I turned off the stir plate for 6-8 hours. The yeast settled and the wort cleared. When I swirled the flask and turned on the stir plate again, there was no fizz from the stir bar. The yeast was done.

I then cold-crashed the flask and poured off the excess. The slurry filled two 1-cup canning jars. After settling overnight and combining the two jars, 1.5L of 1.040 starter yielded just under 1 cup (200ml) of 1084 yeast.

mrmalty.com has some really good tools for pitch rates. Variables include slurry consistency and yeast farm date.

The yeast can stay in the fridge for a week or two without significantly affecting viability. Any longer than that, and I begin thinking about spinning up another batch of yeast.

 

[nebbles]

Great idea! Picked up the fan, and I have a cigar store near me that may have a spare box.

One question is everyone using a fender washer as the piece between the magnet and fan? Curious if anyone used anything else (only other deviation was someone posted a pic of a cutout plastic piece it looked like)

Thanks

 

[taulpepper]

One question is everyone using a fender washer as the piece between the magnet and fan? Curious if anyone used anything else (only other deviation was someone posted a pic of a cutout plastic piece it looked like)

I don't use a washer - I just use a flat steel bracket, following this project: http://www.kjmagnetics.com/blog.asp?p=stir-bars

I never even glued it. I taped the magnets to the bar, then taped the bar to the fan. I occasionally replace the tape just to be safe, but it doesn't move and gets a good vortex.

I used to use a cigar box, but moved it over to a shallow cardboard box that my cell phone came in because it was easier to cut out holes in to see where the bar was and line it up. It's important to be able to adjust the position over the magnets and move it around so you can get it centered and avoid noisy wobbling.

 

[PerryS]

I don't use a washer - I just use a flat steel bracket, following this project: http://www.kjmagnetics.com/blog.asp?p=stir-bars

I never even glued it. I taped the magnets to the bar, then taped the bar to the fan.

In tech-speak, the two magnets need a high-mu magnetic path. For this project, anything that sticks to the magnets and fits on the motor is a good choice.


Drifting a bit, but still on-topic, the kjmagnetics URL shows a 5-gallon bucket being stirred. Bigger fan, but the same idea. This project could be mechanically scaled up to de-gas a carboy of wine or mead. The idea is the same as starter wort - drive off the CO2 and increase the speed of fermentation. A stir bar is much smaller and cleaner than a degassing tool and electric drill motor. I don't know what's in electric motor brushes, but they're being pulverized and dropped into the carboy.

 

[Radobrewer]

How big is the washer used with this fan? I want to pick one up before the fan arrives. Any help on this from anyone is appreciated!

 

[PerryS]

How big is the washer used with this fan? I want to pick one up before the fan arrives. Any help on this from anyone is appreciated!

I used a steel washer about the same size as the stir rod. Fairly thick. Not stainless. Grabbed it from the lower cheap-part bins at Home Depot.

 

[wildcatman17]

when I hook up my pot and turn it slow its starts to smoke whats wrong

 

[Hang Glider]

@wildcatman17:

We're going to need more than that -

EXACTLY how is it wired - can you draw it up and attach, or take a clear photo where we can all see the wires?

 

[PerryS]

when I hook up my pot and turn it slow its starts to smoke whats wrong

Probably too much resistance, or not enough watts. I recommend <12ohms wire-wound, 2 watts. Anything else puts too much power into too small an area on the pot, resulting in smoke.

I use an LM317T wrapped around a 10K pot. See:
http://www.reuk.co.uk/LM317-Voltage-Calculator.htm

R1 and R2 are another way of looking at a 10K pot.
input is 12 volts
output is the fan.

 

[jgonzo108]

Finished mine today. Found the fan local, bought some bolts and a fender washer. Buddy gave me the hard drive magnet and put it all in an old dry box I had lying around.

 

[hausofstrauss]

Easiest DIY stir plate ever! Great job!

I've got the same fan I use when soldering, but didn't think it would have enough grunt for a stir plate.

 

[zacster]

I started using mine as a computer fan too. When it isn't being used as a stir plate I have it up against a vent in my old iMac. The GPU keeps overheating while watching video. I can hear the internal fan struggling to keep up.

 

[smellie_hippie]

Ok Brew Folks…

Thermaltake fan purchased.
Stack of 30 Neodymium rare-earth magnets purchased (1/4 x 1/16 in. disc)
2000 mL flask (purchased)
1 1/2 inch stir bar (purchased)
Cigar Box (purchased from awesome local beer store)

I have the fan mounted to the lid, two magnets glued to either end of the center of the blade (super glue) with polarities properly aligned. (For clarification, that would be two stacks of two magnets). Very little clearance between magnets and lid of the box.

I'm not getting any sort of vortex or spiral from my stir bar (1 1/2 in). I haven't ground off the center bit as has been mentioned elsewhere in the thread. I also don't want to router out the top of the cigar box, because it just look so damn nice! It's pretty thin, and I think the material is barely more durable than balsa wood.

I'm using a 2000 mL flask, and only fill it about 800-1000 mL for test runs. I also didn't glue a washer to the fan blade, but rather glued the magnets directly to the blade housing itself…

Any suggestions or recommendations?

 

[PerryS]

I also didn't glue a washer to the fan blade, but rather glued the magnets directly to the blade housing itself…

Any suggestions or recommendations?

The stir bar provides half of the magnetic path. The washer provides the other half. Air (and glass) in the path diminishes the flux through the stir bar, which is the force that pulls the stir bar around.

You are successful if you can spin the fan blades manually, and the stir bar tracks with it. You may need to stack up more magnets, or get the magnets closer to the 2L flask to get enough force. The spin bar will work in a carboy (1/4" glass) if you stack up enough magnets and get them close enough.

I have a speed control to slowly spin up the stir bar. Otherwise, the spin bar never syncs with the fan and it just lies there, twitching.

 

[smAllGrain]

Flask gets here Tuesday.... BOOM!

 

[shemp]

This is the easiest diy ever!!

 

[moski]

Just ordered the fan, now looking for an enclosure.

 

[TheMadKing]

Just built mine! I pulled the magnets off the back of a name tag. I like the smaller ones better, because the big hard drive magnets were so strong that they bogged down the motor. And I used rubber lab vial stoppers as feet. These work like a charm!

View attachment 1436988588828.jpg

 

[aprichman]

Just got done building mine