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

[Tripod]

Wow, ChillyP that looks great! I'm getting stir-plate envy over here! :cross:

 

[Anthony_Lopez]

Thats a 2" bar I'm guessing...

 

[Catt22]

...but only a one liter flask it appears.

 

[ChillyP]

Yes. That a 2 inch Octagon stir bar. It's a 1000ml flask, which is kind of small. I tried it with a Half Gallon Growler I had filled half way and with some tweaking of the switch and adjust the distance of my magnets I could get the same results.

 

[JCourtland]

I'm sorry if this is on here, but I couldn't find it. Where is everyone getting their stir stick.
Cheers,
Jeremy

 

[gingerdawg]

I'm sorry if this is on here, but I couldn't find it. Where is everyone getting their stir stick.
Cheers,
Jeremy

LHBS or scientific suply store. I got mine at Midwest. They have 1" and 2".

 

[joety]

LHBS or scientific suply store. I got mine at Midwest. They have 1" and 2".

Ditto, using a 2". Most expensive part of the project.

 

[JCourtland]

Cool I found one, it was the last part I needed.
Cheers

 

[Anthony_Lopez]

I bought my stirbars from Morebeer.

 

[ballegre]

Ditto, using a 2". Most expensive part of the project.

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.

How big are are your starters? You using a flask?

 

[rcrabb22]

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.

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

 

[ballegre]

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

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 ....

 

[rcrabb22]

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!!)

 

[ClaudiusB]

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.

2" stirbar in action.

Cheers,
ClaudiusB

 

[Tripod]

ClaudiusB, That is beautiful man!!

 

[slimer]

Claudius, what are the +/- orientation of the magnets?

++--?

 

[alpo]

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.

 

[Anthony_Lopez]

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.

 

[Anthony_Lopez]

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!!)

I actually turned my fan all the way up and managed to throw the magnet right off the washer before I had glued it...

 

[ClaudiusB]

Claudius, what are the +/- orientation of the magnets?

++--?

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

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.

Great idea!


Cheers,
Claudius

 

[ChillyP]

LHBS or scientific suply store. I got mine at Midwest. They have 1" and 2".

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....

 

[ballegre]

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.

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.

 

[Anthony_Lopez]

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.

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]

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 ....

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.

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

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.

[

The 2" magnet configuration also works with a 1" bar.

 

[ballegre]

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.

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.

 

[-TH-]

Here's my build:

 

[SilverKing]

Here's my build:

looks good!

 

[freddyb]

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.

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.

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.

 

[GAX]

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.

Mounted Fan

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...

Hey man, nice job! I got my stirplate up and running the other day and this was a great help, cheers!

 

[Anthony_Lopez]

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!