Drill presses are most commonly used solely for drilling and are difficult to use for machining. If you do not have access to a mill, you can use a drill press for those types of operations. Since aluminum is a soft metal, it is relatively easy to cut, so using a drill press carefully to do so can allow you to avoid finding a mill or paying to use one to cut simple parts.
Insert the endmill you will use to cut the aluminum. Aluminum cutting endmills can be made of high-speed steel and come in two basic types, roughing and finish. If you are taking many cuts, use a roughing endmill, but when using a drill press for machining, you may only want top take small cuts with a finishing endmill. Tighten the endmill in the drill chuck with the chuck key as tight as possible to prevent slipping.
Set up the aluminum to be cut. Since neither the table nor head of the drill press will move, move the aluminum around to mill it correctly. Use a precision block on either side to guide the aluminum to make straight cuts. Clamp the precision block down next to the drill press and readjust it as necessary to complete the cuts needed.
Set the speed of the spindle of the drill press. To cut aluminum, set the drill press at maximum speeds in most cases. Aluminum is soft and if you use the correct endmill suited for aluminum cutting, you will not have any chip buildup regardless of the speed. Bring the endmill down to the require depth for slot milling or edge milling. Reset the spindle lock to maintain the required depth while machining.
Take the cuts slow and be careful as you guide the aluminum into the cutter as it can cause vibration. Cut against the grain, also known as climb milling, as the cutter will catch the material if you cut with the motion of the spinning action. Climb milling assures the part will not slip when you are cutting.
Clamp the aluminum down to mill holes. This is similar to drilling holes, but using a center cutting endmill in place of a drill bit. This requires a special endmill that will cut along the entire bottom edge. This endmill can be used for flat-bottom holes and will work better than a drill. Slowly lower the endmill into the piece, stopping every few passes to check depth.