Bluefront's Lanboy, Part 3: Acoustically Muffled Case Fan Box

Do-It-Yourself Systems
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Sept 3, 2003 by Carl Bohne

This is the last of a three-part article concerning the design, construction, and misc aspects of "Bluefront's Lanboy". The first part covered the intake muffler and filter. The second part described a solid aluminum duct for the CPU heatsink. Part three is about an acoustically muffled case fan box.

So why would you want one of these boxes? Actually it's a very useful project that could serve a number of purposes. Here's a few:

  • A neat roll-around stand that raises your computer about 9" off the floor, and with a drawer can hold CDs or whatever.
  • A hard drive cooler box which mounts the drives out of the case, removing all the heat from your computer with it's own fan.
  • An intake box which could be easily filtered, blowing ambient air into your case from the bottom.
  • Or you could use it like I am, an acoustically muffled exhaust fan box, drawing air out of the computer, cooling your hard drive(s) in the process, and exiting the exhaust out the rear.

Of course maybe you could come up with another use. In any case this box serves one important (to SPCR people anyway) purpose. It allows you to completely close off all the openings at the front of the computer case. I guarantee if all the vent holes in the front of your case are closed, maybe covered with a foam barrier on the inside, your computer will be quieter than before ¬ó no matter what brand of quiet fan you are using in the front.


This box is not hard to make, requiring a drill, a few drill bits, a screw-driver, some #180/120 sand-paper, and some stain of your choice. The wood is up to you. I used oak, but pine is also available, saving you a few dollars. The boards are called "stair risers". available at most places that sell lumber. In the USA they have a standard width of 7 1/4". So for the box (iF you use my dimentions) you need two boards of 7 1/4x48"x3/4". I paid about $21 at Home Depot for oak. Pine boards would have been about $13. Basically I used stair-risers because they were exactly the right width. I only cut the boards to the right length. And they are commoningly available (cheap). You could also use shelf boards (8" wide), but that would have made the box too wide for me.

To make it easy, have the place you buy the boards cut them for you. Home Depot does it for free. If you try cutting the boards yourself, you'll find it very difficult. Out of each 48" board, you'll get two boards 17 3/4", and one board 8 3/4". It is important that the four long boards are exactly the same length. .although they could be shorter or longer, depending on how long you want your own box. The two end boards are exactly 8 3/4".

When finished, my box is 19 1/4 long, 8 3/4 wide, 7 1/4" high. You could adjust the lenght, but if you wanted some other width or height, you could not use a stair riser board. My dimensions should fit almost all standard computer cases.


Take the boards and carefully sand the edges. The rough edge is the bottom of the cut, normally used as an inside edge (not visible). I used simple butt-joints to attach the boards to one another. Pre-assemble the boards to get the best fit. Put the best boards as the sides. the top and bottom board won't be visible.

Pre-drill all 16 holes in the two sides. I counter-sunk each hole because I covered each screw with a wooden plug, This is only an appearance item, not necessary. I used 16 screws, # 10x1 1/2" wood screw. The hole should be slightly larger than the screw. You want this screw to tighten into the second board, not the outer board.

The easiest way to make the setup square is to use devices as shown in the pictures below. Not sure the name of the things, but they work great. They're cheap. I used four, which held the whole box tight, before I drilled the final holes. (Editor's Note: They're probably called something like corner board clamps.) If you don't want to buy these things you'll need some way to hold the boards as you drill, maybe a helper. As you can see, the top board is 1/4" lower than the top edge of the side boards. This gives enough clearance for the rubber feet of the case to sit(prevents the computer from sliding off the case). You may have to trim these feet on the edges (I did) to fit the available width (7 1/4"). With the case clamped together you drill the 16 holes( slightly smaller than the screw), using the previously drilled holes as a guide. Screw in one screw as you drill each hole.

After screwing the case together tightly, I sanded everything. No matter how careful you are, you will have to sand the two ends of the box, making it as flat as possible. I then attached the carpet castors using 16 screws, #8x3/4".

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