Finally we get to play with some power tools, but like always, safety first! Safety glasses are a must when cutting and drilling as it creates a lot of debris that could damage your eyes. I would also recommend checking your measurements and clearance again at this point, as it is the last chance. There are a few options when it comes to cutting fan holes, let's take a look at each of the preferred methods.
- Hole Saw
Instantly this is what most people think will be the easiest way to cut fan holes, but this method has some hidden catches. Firstly the larger hole saws capable of 80-120mm holes are fairly expensive and can range from $30 upwards. This is fine if you plan on cutting a lot of the same size holes, but for one off jobs, it can be an expensive odd job. Secondly to get a clean cut at these larger sizes ideally you should use a drill press to account for chattering. Unfortunately a drill press is a tool not everyone can afford or has immediate access to.
If you decide to proceed down this path using a hole saw and drill press, first drill a small pilot hole into the previously marked out center point. Once the pilot hole is complete, proceed with your hole saw cut slowly with your press at a high speed to avoid rough cuts. Some metal cutting fluid/oil may also help the process run a bit smoothly.
One thing that should be noted when using a hole saw is the resulting holes are always slightly larger, as the hole saw cuts to the size of its outside circumference. Keep this in mind as once you have cleaned the cut up it may be slightly larger than you were intending.
This is my preferred method of cutting holes. Start by clamping down your panel and then drill a pilot hole on the inside of you proposed cut. This needs to be far enough away to allow for the larger size hole that needs to be made next.
Now the pilot hole is completed move up to a larger size drill bit to extend the hole. I use a 1/4" size drill bit as this allows for the jigsaw blade to fit comfortably with enough leeway for easy manoeuvrability.
With the larger hole drilled hopefully as close to the cutting line as possible we now take our jigsaw with a sharp new metal blade as this will help with cutting out a circle. Place the blade through your drill hole and proceed to cut around the circle. The trick to cutting round patterns with a jigsaw is cutting slowly and trying not to twist and force the blade. Let the tool do the work for you!
Cutting rounded shapes with a jigsaw can be daunting and a bit tricky at first so if you are unsure its best to give it a trial run on some scrap first. The way I learnt to cut panels was by using old beige case side panels that I no longer needed.
- Rotary Tool
Another of the most preferred methods is using the always reliable rotary tool. It's always best to use diamond cutting wheels when working on thicker case panelling as they tend to last a lot longer. Clamp down your project making sure you have a clear cutting area below, hold your rotary tool at a 45 degree angle using both hands making sure not to block the tools ventilation. Although this method may be a bit more time consuming than the jigsaw, it allows a lot more control for the novice modder.
Still holding your rotary tool at 45 degrees, slowly work your way around the cutting line using the curve of the cutting disc to cut a perfect circle. Don't apply too much pressure and when you see the cutting wheel has made its way through to the other side, move onto the next section and continue cutting.
Again let your tools do the work and try not to use excessive force to try and speed up the process. With a slow steady hand you will find yourself wearing your cutting wheels out instead of shattering and snapping them at regular intervals, hence ultimately costing money.
Drilling the Mounts
Drilling your mounting holes is a straight forward procedure which can be done with your hand drill or a drill press. Clamp down your panel onto a thick scrap wood backing or bench, using a 1/4"³ drill bit and a straight vertical motion slowly work your way through the panel. If you are worried about slipping or rolling the drill bit, I would suggest using a center punch or pilot hole to pre-mark out planned holes.
Clamping Tip: When clamping down materials for cutting or drilling, it is best to clamp your item as close to the work area as possible. This will help reduce unwanted reverb and chattering while attempting delicate work.