The Quetzalcoatl CaseMod, Part 2

Part 2: Tear it down to build it up. or Removing parts not needed to make space for the ones that are.

Cover up that window!
This case design does not involve windows and fancy internal lighting, so the side case window and fan are removed and replaced with a solid panel. A piece of thin sheet steel is cut to fit the window opening and attached with sheet metal screws. I probably could have left the window in place, but the steel adds some strength and rigidity to the side panel.



As I mentioned in part 1, I will be mounting two radiators inside the case; one will fit in the front air-intake area, so the 3.5" drive bay assembly had to be removed. The second radiator is too large to fit inside the case where the rear fan is located, so I will mount it to the top of the case between the power supply and the optical drive.

To modify the 3.5" drive bay assembly, I drilled out the pop-rivets holding it into the case. With a diagonal grinder, I cut off the lower portion of this assembly and then folded the sides over to form a new bottom plate under the drives. With the six drive bay frame now shortened to a two-bay version, I reattached the assembly with sheet metal screws. Once drive bay modifications were complete, I mounted the optical and floppy drive, but covered them with paper and masking tape to keep dust, metal filings, and other craft-related debris away from their openings.

A simple 120mm fan template
To position and drill holes for installing a top fan and radiator, I took a 120mm fan and scanned it at 600 dpi, then adjusted the gamma until I could easily identify the mounting-hole positions. While I had the image in my photo editing software, I added white circles in the center of the mounting holes, and drew two diagonal lines between the corners to identify the approximate center point of the fan. After straightening and trimming the image, the result was a ready-made pattern to print out for a drill-hole template.

Click here for a pdf file with my 120mm fan image template. To print this at the correct scale, set your printer page setup for 600 DPI (or so that the image size is about 4.75 inches across on the page). When you go to print from Adobe, be sure to set the page scaling to "none". Check it against your actual fan before drilling.



Cutting a new one
A step-by-step process for adding a "blowhole" exhaust fan to the top of a case.



Step 1: Print the template.
Position and attach it to your case where you intend to drill and cut. Because I had to center the fan between the power supply and drive bays, these had to be installed to make sure I had clearance around the fan. Before drilling or cutting, remove your drives and PSU to avoid damage!



Step 2: Drill starter holes.
Even if you have a metal punch, starter holes will help the drill bit to stay in place when you switch to the larger size. I'm using a 1/8" drill bit for starter holes, and then a larger bit that just fits inside the fan holes for the outside four. (Don't worry about enlarging the center hole, the hole saw has its own drill bit.)



Step 3: Cut round hole into case.
Using a 4.5" multi-purpose hole saw for the 12cm fan, cut a nice round hole in the middle of your template.



Step 4: File the sharp edges off with a half-round file.
If you haven't drilled the screw holes larger yet, you can do that now. Vacuum out all of the metal dust you created; you don't want that getting into the drives or where it could short something out.

Fan Hole Cutting Tips:
To mount a fan in a case where you have to cut new holes, scan or make a photocopy of the fan as a template for positioning and drilling the mounting holes. You can use all-purpose or metal hole-saws available from your local hardware store to cut the large opening for air flow:

• A 120mm fan needs about a 4.5" hole


• A 80 mm fan needs about a 3" hole.


• Use a sheet metal deburring tool or a half-round metal file to remove sharp edges left from the cutting process.


• Mount a fan grill or filter over the hole keeps fingers away from any sharp edges as well as out of the moving fan blades.


• If you can find it, plastic edge strip can be used to line the sharp edges of hole.

Next time: Hinged panels