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General Category => Pimp My System => Topic started by: green_dragon on April 01, 2011, 06:02:58 PM

Title: My homemade stir plate, aerator, and propane burner
Post by: green_dragon on April 01, 2011, 06:02:58 PM
So I decided to take the next step and construct my own magnetic stir plate.  I didn't want to spend any money on it except for the stir bar.  I made it completely from parts laying around the house.  If you're not a computer geek you may have to buy some of this stuff.

Parts List:
80mm computer fan (scavenged from an old computer)
2 x rare earth magnets (scavenged from a Western Digital 30gb hard drive)
7.5v AC to DC phone charger (from an old phone I had at one point)
4 x #12 1.25" wood screws (had extra's laying about from a home improvement project)
8"x10" sheet of clear Acrylic (I mod my own computer cases so I have extra laying about)
Backing from an old picture frame (explained below)
Electrical tape

I started off with a 120mm fan I had laying around but I found out 120mm fans just don't have the rpm's needed to create a vortex so I went out to the garage and pulled an 80m fan off an old P4 system I keep around for parts.

I pulled apart a hard drive from an old computer.  The rare earth magnets are located in the base of the arm, as seen in the picture.

Insulating the fan hub
I found out that if I just glued the magnets strait to the fan hub the magnets would create enough resistance to cause the fan to slow down and sometimes not start on its own.  To remedy this I tried a double layer of some spare clear acrylic sheets I have laying about but evidently clear acrylic doesn't insulate against magnetic forces very well.  I wanted to use wood but don't have any spare wood laying about the house so I used the backing of an old picture frame and cut it into circles the same size as the fan hub.  I used two layers of it to be safe.

Mounting the magnets
I actually only used one rare earth magnet that I broke in half.  I made sure to make sure each piece was facing the right way first before super gluing them to the fan hub insulators.  I found that just a little space between them works best.

For some odd reason I've kept every cell phone charger I've ever owned.  I think I may be an electronics horder.  I pulled the box of chargers out of the garage and sorted through them.  I knew from reading web guides, and this forum, that 12v is way to much but 6v isn't quite enough.  I found one that was 7.5v and went with it.  Probably blind luck, but it works perfectly.

Part 2 incoming:
Title: Re: My homemade stir plate
Post by: green_dragon on April 01, 2011, 06:04:39 PM
Picture of my epic splicing job, lol.

Flask base
This is one that may not be "free" for some people.  I mod my own computers so I have spare sheets of clear acrylic.  They are about $3 at Home Depot.

Fine Tuning
I knew that I was going to have to dial in the right distance to get the stir bar working.  Really I was just being lazy on this part but it works out surprisingly well.  I just found some old wood screws from a home improvement project I did and screwed them into the case fan holes you use to mount the fan to the computer case with.  The screws are flat on top so the acrylic sheet lays flat and I can adjust the height with just a few twists.

Finished Product in Action
Here is the finished product in action.  The vortex goes all the way down to the stir bar, but it's hard to get a clean picture it.  I left it running for a long time.  Nothing got hot, or off balance so I'd say it's a success.  Stirs 750ml of water with no issues.  Did the Coopers wheat beer starter using Wyeast 3333 and it ran just fine for 48 hours on the stirplate.
Title: Re: My homemade stir plate
Post by: euge on April 01, 2011, 06:15:58 PM
Made nearly the same device, but you did some things more cleverly that me. Nice bit with the screws and paper. I also added a cheap rheostat from radio shack.
Title: Re: My homemade stir plate
Post by: dzlater on April 02, 2011, 10:59:45 AM
Using the screws to adjust the height was pretty clever.
Hadn't thought of that.
Title: Re: My homemade stir plate, aerator, and propane burner
Post by: green_dragon on April 10, 2011, 01:43:38 PM
For the burner I took an old propane smoker and cut the base off.  It took me 5 dremel blades but it was worth it!

Top I cut off:

View from the bottom where I did the cuts:

Better view of the cuts:

Finished product in action:
Title: Re: My homemade stir plate, aerator, and propane burner
Post by: green_dragon on April 10, 2011, 01:48:16 PM
The aerator is just a $9 aquarium fish tank pump from Wal-Mart.  There is a cheaper one but it's only a single tube.

I took the two tubes and zippy tied them to a metal coat hanger I had straitened out and sanitized:

Sorry no shots of it in action, I forgot to take a few yesterday, but it works well.
Title: Re: My homemade stir plate, aerator, and propane burner
Post by: bluesman on April 10, 2011, 01:51:35 PM
It never ceases to amaze me the clever ways that which homebrewers work.

Well done green_dragon !  8)