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

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ballegre said:
I have a 2" also but I think it's causing me problems. I find that it gets off center easily and gets thrown a lot. I'm using a 1.5L coffee press as a vessel.
Click to expand...

What an idea! In my travels I worked for a failed dot.com and when we closed we raffled off the kitchen supplies and I won the Starbucks french press. I might have a starter vessel and didn't know it!!

Do you think you stir bar issues are due the french press vessel or fan speed
 
rcrabb22 said:
What an idea! In my travels I worked for a failed dot.com and when we closed we raffled off the kitchen supplies and I won the Starbucks french press. I might have a starter vessel and didn't know it!!

Do you think you stir bar issues are due the french press vessel or fan speed
Click to expand...

I'm thinking the stir bar is my problem but I'm not sure. I tried different fans, many power supplies and many magnets. It works most of the time with deep vortex but I have to play with it a bit. It's not consistent.

I bit the bullet and ordered a 1" stir bar from midwest to test. The french press vessel seems to work fine. Bottom is nice and flat. It might even be pyrex so I can boil and chill without transfer but I don't want to risk it if I'm wrong.

I'm wondering if the flasks have slightly concave bottoms so the stir bar auto-balances and spins better due to less friction ....
 
Hopefully not a stupid question but do you really need to glue the hard drive magnet to the steel washer? My magnet feels firmly attached to the steel washer on it's own. Will influence from the stir bar be strong enough to move the magnet from it's location on the fan?

Thanks so much to Tony for posting this. With parts and instructions even an all thumbs guy like me can build this (and I did Wooo Hooo!!)
 
My solution to all the different problems I have encountered, flasks shapes, sizes, etc.

The four magnets have a pull force of 5 lb each.
MagnetsBothSets.jpg


2" stirbar in action.

StirBarLargeInAction.jpg



Cheers,
ClaudiusB
 
Claudius's is similar to mine. I use 4 magnets across in a line, --++. I have had the most success with this orientation. It greatly reduces the tenancy of the plate to throw the stir bar at high speeds.
 
Very nice!! I'm going to start going through this thread to post different magnet setups people have used that have been successful in my original post.
 
rcrabb22 said:
Hopefully not a stupid question but do you really need to glue the hard drive magnet to the steel washer? My magnet feels firmly attached to the steel washer on it's own. Will influence from the stir bar be strong enough to move the magnet from it's location on the fan?

Thanks so much to Tony for posting this. With parts and instructions even an all thumbs guy like me can build this (and I did Wooo Hooo!!)
Click to expand...

I actually turned my fan all the way up and managed to throw the magnet right off the washer before I had glued it...
 
Claudius, what are the +/- orientation of the magnets?

++--?
Click to expand...

Claudius's is similar to mine. I use 4 magnets across in a line, --++. I have had the most success with this orientation
Click to expand...

NN SS pole

Info:
My fan is a 120mm, 24 VDC.
The 24 V fan I picked has more torque than the 12 V version.
Magnetic shielding (washer) is a good idea for most fans.
My selected fan has metal plates below the plastic covers, no washer required.

I'm going to start going through this thread to post different magnet setups people have used that have been successful in my original post.
Click to expand...
Great idea!


Cheers,
Claudius
 
gingerdawg said:
LHBS or scientific suply store. I got mine at Midwest. They have 1" and 2".
Click to expand...

I got mine from McMaster-Carr. I also picked up a stir bar retriever too....

I also did mine so I can bring the fan in closer, so I could adjust for the different stir bars and vessels I used. I have uploaded a video on youtube.



I'm just messing with it, but I ran it for 4 hours with no stir bar throw....
 
Last edited by a moderator:
alpo said:
Claudius's is similar to mine. I use 4 magnets across in a line, --++. I have had the most success with this orientation. It greatly reduces the tenancy of the plate to throw the stir bar at high speeds.
Click to expand...

I think part of the problem I'm seeing is that the hard drive magnets are curved so it's difficult to find the center of the magnet and balance on the fan. I found that if I used a single curved magnet with a 2" stir bar, which is longer than the magnet, the bar would not center over the magnet - it kinda favored one end of the magnet. I had to add a second curved magnet to make it longer than the stir bar and it centered. This, however, made it more difficult to find the center of the magnet to balance on the fan.

I think there might be a difference between the "magnetic" center, which the stir bar requires for balance, and the "rotational" center, which the fan requires for balance. If these two points aren't the same, there's going to be problems. I'm not sure they are with this set up.
 
ballegre said:
I think part of the problem I'm seeing is that the hard drive magnets are curved so it's difficult to find the center of the magnet and balance on the fan. I found that if I used a single curved magnet with a 2" stir bar, which is longer than the magnet, the bar would not center over the magnet - it kinda favored one end of the magnet. I had to add a second curved magnet to make it longer than the stir bar and it centered. This, however, made it more difficult to find the center of the magnet to balance on the fan.

I think there might be a difference between the "magnetic" center, which the stir bar requires for balance, and the "rotational" center, which the fan requires for balance. If these two points aren't the same, there's going to be problems. I'm not sure they are with this set up.
Click to expand...

This is one of the main reasons I used the steel washer. It allows you to fine tune your magnet placement before committing with epoxy.
 
ballegre said:
I'm thinking the stir bar is my problem but I'm not sure. I tried different fans, many power supplies and many magnets. It works most of the time with deep vortex but I have to play with it a bit. It's not consistent.

I bit the bullet and ordered a 1" stir bar from midwest to test. The french press vessel seems to work fine. Bottom is nice and flat. It might even be pyrex so I can boil and chill without transfer but I don't want to risk it if I'm wrong.

I'm wondering if the flasks have slightly concave bottoms so the stir bar auto-balances and spins better due to less friction ....
Click to expand...

Now that I have a 1" stir bar everything is working really well. There are definitely some challenges using a 2" stir bar with a ghetto flasks/vessels.

I found that positioning the magnets while the stir bar is on top helped me find the magnetic center and the rotational center.

This is a magnet and the 1" stir bar configuration that works.
DSCF0833.jpg


Before, I had the 2" bar in this configuration and it just doesn't work.
DSCF0832.jpg


So that lead me to take a couple of smaller magnets and spread them out. Now the configuration looks like this for a 2" bar with a 2" magnet spread.
DSCF0831.jpg
[

The 2" magnet configuration also works with a 1" bar.
DSCF0830.jpg
 
So I'll keep the 2" magnet orientation. The stir bar is most fussy in my growler. The 2" stir bar will not stay put in that growler. The bottom must have some irregularity that throws the bar even at low speed. Interestingly the 1" works very well in the growler. The picture below is a 1" stir bar with a growler.
DSCF0835.jpg

The vortex is a bit narrow but I can kick up a lot of air when it's running at high speeds.

The 2" stir bar works well in the french press carafe that can be seen in the background. Very wide, frothy vortex from it but only 1.5L. Should work for most starters but for lagers I'll probably need the growler or something larger like a 3L flask.
 
Here's one I put together last weekend. Works great with the 25mm micro stir bar and 1 liter Bomex flask from Northern Brewer. I'm guessing it would also work well with a 2 liter setup too.

1001734.jpg


I wired the fan directly to a universal AC/DC adapter that I found in the basement and I can control the fan speed and vortex size by changing the voltage, current or both.

The washer is affixed to the fan with a piece of double sided tape and the rare earth magnets are simply...magnet-ed(?) to the washer. I haven't had any problems with them sliding around on the washer and I like this setup because it allows me to adjust them easily.

1001736s.jpg


The height of the fan is adjusted by raising or lowering the nuts on the bottom.

Nothing really original here, just thought I'd add it to the pile.
 
Anthony_Lopez said:
P1010512.JPG

Power Switch Wiring

Assuming everything has been done correctly, plug in your power supply, flip your power switch to the “On” position, and try turning the knob on the potentiometer back and forth. You should be able to observe the fan speeding up and slowing down as you turn the knob back and forth.

Now, we need to take the steel washer and glue it onto the fan. I used some 60 second epoxy so that I could turn the fan on and off to observe if the washer was centered on the center of the fan.

The next steps in this project is to fine tune the positioning of the fan within the enclosure, and try magnet combinations and positions until you get your bar spinning correctly.

I used 2 ½ inch 10/32 bolts with matching nuts and washers to mount my fan. I also used some ¾ inch stand offs to raise the fan. Instead of the standoffs, you can use extra 10/32 nuts to position the fan up and down the bolts. I also found that you need to drill out the holes of the fan to get the bolts through. 8/32 bolts will work without drilling.

P1010504.JPG

Mounted Fan


P1010500.JPG

Bottom Side of Aluminum plate with fan mounted and secured.

Your project enclosure should have come with both an aluminum and a plastic sheet to close up the enclosure. I drilled out the pattern for my fan's mounting holes into my aluminum sheet, and then mounted the fan. Once I had everything drilled out and mounted, I put every thing together, and tried it out...

Good Luck!!!

Also, for all you other DIY'ers, let me know if you catch a mistake or typo on here so I can edit...
Click to expand...
Hey man, nice job! I got my stirplate up and running the other day and this was a great help, cheers!
 
Thats for the kind words! As of now, I have replaced my hard drive magnets with ones from K&J Magnetics. They are MUCH stronger and much smaller. I have tested this setup with a 12VDC wall wort and as of last weekend did a .75 gallon starter on it using a 1 gallon glass jug from whole foods apple juice. Worked great!
 
Anthony_Lopez said:
Thats for the kind words! As of now, I have replaced my hard drive magnets with ones from K&J Magnetics. They are MUCH stronger and much smaller. I have tested this setup with a 12VDC wall wort and as of last weekend did a .75 gallon starter on it using a 1 gallon glass jug from whole foods apple juice. Worked great!
Click to expand...

which magnets di you end up using from K&J Magnetics?
 
I've read the whole thread, and plan on building one. I need to get a flask still. Should I get the 1000 or 2000 ml??? Does the stir plate increase the yeast enough to use the 1000 ml?

Thanks.

-Aaron
 
AJWELLS said:
I've read the whole thread, and plan on building one. I need to get a flask still. Should I get the 1000 or 2000 ml??? Does the stir plate increase the yeast enough to use the 1000 ml?

Thanks.

-Aaron
Click to expand...

For most normal ales a 1L(1000ml) starter is sufficient. If you plan on doing bigger ales or lagers you might want to look for a larger vessel for starters up to 5L.

That said, you don't have to use a Erlenmeyer flask. Any container with a relatively flat bottom should work. Another member posted pics of a stirplate with a glass apple juice bottle and I've been looking at the 4L wine jugs for bigger starters if I need to.
 
I just built my own stir plate--haven't used it yet, but plan to do so next week. To answer the question above regarding flask sizes, etc.: I'm planning to use a cheap vase that has a flat bottom as the vessel for my starter. It's glass, easily washable/sanitizeable (is that a word?), and best of all, very inexpensive (I probably got it at Wal-Mart a few years back for under $3). I'm planning to put some sanitized aluminum foil over the mouth of the vase to try to keep the nasties out, but loose enought to allow at least a little bit of gas exchange; either that or some saran wrap and a rubber band...
 
Remember for a 1L starter, you need a vessel larger than 1L. I use a 2L flask for my starters, and a 1L flask for culturing.
 
I mocked up my stirplate and something just ain't right. I'm using a 12V power supply with a surplus .2 amp fan. I epoxied a big washer to the hub and am using 2 rare earth magnets, a 2" stirbar, and a 2L flask. So my problem is that it's very difficult to get the stirbar to "catch" and it usually gets thrown. When I can get it to catch the vortex only goes about halfway down the liquid level and certainly isn't the maelstrom of bubbles everyone else seems to have. What's the likely culprit? Magnets? Positioning? Spacing? I have a suspicion that my fan is spinning too fast and isn't torquey enough but would like to hear everyone's thoughts...
 
Another question for you....My power supply doesn't have color coded lines, just 2 braids of copper. Which is which? I seem to remember something about the printing on the outside, but I don't remember. Thanks
 
Damonic said:
I mocked up my stirplate and something just ain't right. I'm using a 12V power supply with a surplus .2 amp fan. I epoxied a big washer to the hub and am using 2 rare earth magnets, a 2" stirbar, and a 2L flask. So my problem is that it's very difficult to get the stirbar to "catch" and it usually gets thrown. When I can get it to catch the vortex only goes about halfway down the liquid level and certainly isn't the maelstrom of bubbles everyone else seems to have. What's the likely culprit? Magnets? Positioning? Spacing? I have a suspicion that my fan is spinning too fast and isn't torquey enough but would like to hear everyone's thoughts...
Click to expand...

If your bar is getting thrown, then its either too fast a fan speed or not enough of a magnetic attraction. I would try getting the bar centered perfectly in your flask while its on the plate, and then mark the outside circumference of the flask's bottom on some masking tape. This will help you center your flask.

The next issue of magnetic attraction is more a matter of trial and error. Extra magnets are quite helpful. I can tell you from first hand experience, I have had much more issues using a 2" bar than a 1" bar. My flask needs to be perfect to get the 2" working. The 1" centers easily and will catch and spin almost 100% of the time. Try a single magnet in the center, or two magnets stacked in the center... then try moving magnets out opposite each other. Its just a matter of tweaking it til it works with your equipment.
 
JGDrng said:
Another question for you....My power supply doesn't have color coded lines, just 2 braids of copper. Which is which? I seem to remember something about the printing on the outside, but I don't remember. Thanks
Click to expand...

There has to be some sort of insulation, or the power supply would short out with just bare copper. I'd bet that the insulated wires are inside the copper braids.
 
I guess I didn't explain that very well. The cord looks like you cut an extension cord off at the end. There is no black or red line. Just 2 copper strands inside the insulation.
 
Damonic said:
I mocked up my stirplate and something just ain't right. I'm using a 12V power supply with a surplus .2 amp fan. I epoxied a big washer to the hub and am using 2 rare earth magnets, a 2" stirbar, and a 2L flask. So my problem is that it's very difficult to get the stirbar to "catch" and it usually gets thrown. When I can get it to catch the vortex only goes about halfway down the liquid level and certainly isn't the maelstrom of bubbles everyone else seems to have. What's the likely culprit? Magnets? Positioning? Spacing? I have a suspicion that my fan is spinning too fast and isn't torquey enough but would like to hear everyone's thoughts...
Click to expand...

I chose to go against the popular dogma and use a 110 V AC muffin fan with an ordinary light dimmer for speed control. I had much the same experience as you describe trying to get a 12 V DC fan to work.

I use a 2 liter flask with a 2 inch (50mm) stir bar and typically fill the flask well above the 2000 ml mark to about 2300 ml. Foam control is a must when boiling wort with the flask filled to that level, but I do it all the time without problems.

I used two off the shelf very strong rare earth magnets to achieve the magnetic coupling strength needed. I got tired of trying to balance the salvaged hard drive magnets and the hassle of removing them from the drives. The store bought magnets are inexpensive and well worth the cost.

3213621211_f19ac62649.jpg


3214468874_7f5b31f7bf.jpg


3214468632_fcfa557578.jpg


3214470406_32d1bdd118.jpg


3213623577_07e810ee26.jpg
 
JGDrng said:
I guess I didn't explain that very well. The cord looks like you cut an extension cord off at the end. There is no black or red line. Just 2 copper strands inside the insulation.
Click to expand...

Take a close look at the outer insulation. There may be one with ribbs and that would be the positive side. The other possibility is that one of the wires is a gold (copper) color and the other silver. The gold one is the positive wire in most cases.

You could also just hook it up and see if it works. If it doesn't work then switch the wires.
 
Another question for you....My power supply doesn't have color coded lines, just 2 braids of copper. Which is which? I seem to remember something about the printing on the outside, but I don't remember. Thanks
Click to expand...
Here is what you can do, I am assuming it is a 12VDC fan.
Connect the two wires of your 12VDC fan to your power supply.
The fan can only do two things, spin or no motion.
DC fans come only in two versions, with or without polarity protection.
If the fan doesn't spin reverse the wires, the fan has to move.
The non polarity protected fan will rotate as soon you connect the 12 VDC.
Since you are not using the fan to move air, the direction of fan rotation is not important.
If the direction of rotation is important, look at the fan marking for rotation direction.

Cheers,
ClaudiusB
 
I built my stir plate this weekend and it was a success. However, I did get frustrated with the wiring because previously posted wiring instructions did not work for me, so I drew a wiring diagram for others who may find it useful. The colors of the wires all match up correctly. You only need to provide a spare wire that is depicted in green, or cut the yellow ground wire from your fan and use that.

wiring3.jpg


I hope someone finds this diagram useful and it wasn't a bunch of wasted time.
 

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