Fitting a case fan

Another, slightly more complex, variation of a fan hole is the ‘screw-less’ look top blow-hole. With this application the concept is to conceal the fan screws and give the mod an OEM look. The first step is to fabricate a ‘fan-to-tube converter’ out of an acrylic off-cut. The 8mm sheet is marked to match the size of the fan, and the central point marked and drilled with a 1mm bit. A compass is then used to scribe a circle that is just slightly smaller than the outside diameter of the tube, which in this case is 110mm. You might have noticed that there are two lines, the inner being for the initial cut, while the outer line is for the final dimension, and will be achieved by grinding out with a drum sander. The tube has to be an ‘interference fit’ inside the converter, which means that it needs to be as tight as possible so that they clamp together. A pilot hole is then drilled as a starting point for the jigsaw, using a Brad Point bit, which work really well in plastic. After cutting the hole out with a jigsaw, using a coarse wood blade at high speed, the edges are sanded and smoothed until the tube can only just be forced into the hole. The four mounting holes for the fan are then drilled and countersunk into the converter, on the side that will be pressed against the inner surface of the case top.

Once the case top has been cut to accept the port, in this case a flared bass-reflex tube from a sub-woofer, the tube can be cut to length so that it just reaches the bottom of the converter – the thickness of the case plus the thickness of the acrylic section, 9mm in this instance.



Removing the top panel from the case will make life much easier when cutting and sanding, even if it means drilling out the rivets used to secure it. As we have suggested previously, it is a good idea to use masking tape to cover any case panels that you are working on, as it will help avoid scratches in the finish – as well as providing a better surface for drawing templates and lines. The 110mm hole for the tube was marked out, and then cut out with a jigsaw using a fine-tooth blade. After filing and sanding smooth, the port tube can be cut and glued to the case with epoxy glue.



The assembly of the converter/fan component is a sandwich; the converter is screwed to the fan, with a square of speaker grill between them to act as a grill. A 120mm chrome wire fan grill is attached to the side of the fan that is open inside the case. The final step is to fit a siliceous fan sheet around the port opening, to reduce fan vibration, and press-fit the fan assembly onto the port tube. If the two components are not a very tight fit, epoxy glue can be used to make it a permanent fitting.



And beyond!

Running out of word space mid-topic is annoying, but there’s always next month! There are several more fan-fitting applications that are worth covering, including methods of painlessly replacing small existing fans with larger ones, that we can look at later. We will also have a closer look at some of the purpose-specific tools that are worth adding to your inventory. Meanwhile, if you’re new to the prospect of modding your own case but want to get involved, our suggestion is to grab an old case and jump right in. The easiest way to gain skills is to practice and make mistakes.