This is quite simple, a 120mm PC fan is attached to a stand. And has some nails placed in it to hold the carbon filter, for easy replacement.
- 120mm fan, easily scavenged
- 4 nails
- carbon filter, a 3 pack is $5 at DigiKey
- 1/8" thick polystyrene or acrylic or Masonite
- Methylene Chloride (acrylic cement) for styrene & acrylic or wood glue for masonite.
-Acetone will work for acrylic and styrene, takes longer though, look around online for info
- Drill and bits
- Something to cut a hole out.
- a Band Saw, Jig saw, rotary tool, hole cutter, key hole saw
UPDATE: Added a better air hood and painted it black. Added the images and notes.
Step 1: Cut the Hole
Without this front piece air was deflected back out between the edges of the fan blades and housing. This helps keeps that from happening to much, and creates a much better suction.
Cut a 12 cm x 12 cm square of styrene, acrylic or Masonite. ( 4.5" x 4.5" works fine )
Draw lines diagonally, corner to corner.
Use the center point to draw your circle, with a compass or however you draw circles. 4.25" diameter circle worked for my fan. It should overlap the edge of the fan blades, blocking the gap between blade and housing.
Depending on what medium your using (styrene, acrylic or masonite). Choose a good tool for cutting out the hole. I used a band saw and just cut into it from the edge, and I had to glue the cut closed again. It doesn't have to be pretty, just keep it pretty close. Then clean it up with a file or sand paper.
Place the fan on the circle and mark where the mounting holes will go.
Find some screws that fit your fan's mounting holes, then choose your drill bit. Drill them out.
Step 2: Rest of the Stand
The bottom piece should be at least an inch longer and about 3" wider. Mine worked out to 5.5" x 3"
Other 2 pieces are the same. Some scraps are fine, they should be at least 1/2" x 1.5"
Look at the picture below.
*note* I suggest moving the piece with the hole in more towards the center.
Draw some lines with a t-square to align the pieces and make them square.
Apply some glue to the edge of your medium, and glue it up. You might have to prop it up while the glue dries.
Step 3: Prepare the Fan
Simply enough, find a nail that fits well into the hole, and put it in head first, so the pointy end is up. If you need to, put some glue in the hole first.
See images for details.
If your carbon filters are to big, cut them down.
The bottom of the fan and filter need to be flush so it will fit in the stand.
The other 3 sides can hang off, just the one side needs to be flush with the fan housing.
Press the nails through, so there is one coming out each corner.
Using some plastic or rubber, push it onto each of the nails to hold the filter on snug. Some small corks or rubber stoppers would be preferred.
Step 4: Assemble and Finish
I made a new hood out of 100mil styrene and glued it on. And gave it a nice black paint job with some Krylon Fusion(for plastics)
After the glue dries, screw the fan, with filter attached, to the stand. It only needs two screws, find the two holes that match up best.
Adding a hood will really help direct airflow. See diagram in images.
Tape the seams together, then tape it onto the outside of the fan housing.
Check the fan for its current rating, should be 200-400ma.
Find a suitable 12 volt power supply, and wire it up to the fan, minding the polarity. Red to positive, black to negative. I use a modified PC PSU to power it.
Check out my website for more Projects, Info, and Kitst
Take a look at my other Instructables
High Power RGB LED Driver
Full Stepping Parallel Port CNC Driver
Look for my upcoming instructables
LED Infinity Mirror on the cheap soon with Chase Pattern Driver
Remote servo pan/tilt camera
Enjoy your cleaner air.
Step 5: Version 2
So I liked the one I built but it wasn't quite strong enough so I purchased a 120v AC fan of the same size with a cast iron housing, for $9.95 surplus.
I thought I could just swap the fans with the old housing but of course it wouldn't fit right, so i built a new one. The same way with polystyrene. Painted it silver. It is quite powerful and more than does the job, loud though.