Features and working of an air drill

An air drill works on the principle of converting the latent energy of pressurized air into mechanical force. This energy provides the forward thrusting as well as rotational force to the drilling bit attached to the front of the drill. The operator presses this drill tip against the point on the surface of the material that is to be drilled into. The drill bit has a pencil-like construction with a serrated, rounded tip. This tip, through its rotational motion, is designed to shear of thin slices or grind away minute granules from the material it is burrowing into.

Most air drill are designed to be used by a single person with user friendly controls, and a sturdy, contoured handle which can be gripped with a single hand. Some drills have an auxiliary side handle aside from the main handle that the user can grip with the free hand to ensure an even tighter grip of the tool. In some drills, the user has the option of detaching this auxiliary handle. This feature becomes very useful when drilling into hard materials and also to increase accuracy. In addition to drilling, this tool also enables hole sawing, reaming, wire brushing, polishing, and honing. The drill is rendered with an exhaust built into the handle.

The body of the drill is made of a reinforced, rugged material to ensure durability and a long life. The angle of the handle in relation to the direction of the drill bit is ergonomically designed to ensure minimal stress on the hand and the wrist. The throttle to control the speed is adjustable. A planetary gear reduction feature equalizes the load on the bearings and the gears, prolonging the tool life. The drill chuck, which constitutes a set of jaws encircled by a collar, holds the drill bit in place securely and the most common measurement for the chuck is 3/8 inches. The power that the drill exudes depends on the flow of air, which is measured as cubic feet per minute (CFM). The CFM value for the different drill models vary from approximately 2 to more than 20. The rotational speed varies from around 1800 rotations per minute (rpm) to 2500 rpm. A majority of Air drills have a ¼ inch air inlet. Normal handheld air drills have a weight of around 1 to 2 kilograms. Aluminum housing helps to lighten the weight of the tool even further. Air drills can be lighter than electric drills as the compressor is capable of being separated from the actual grill body.

Another type of air drill called a spot drill is used to drill holes into steel plates and also to smoothe uneven welded portions. These drills have a hook to enable the user to hone in on the drilling position.     

What to look for in an air drill

Depending on the use of the drill and the budget, the user can decide on the power as well as the size of the drill. Normally, a heavier drill is more stable and prevents any kinks or dents being rendered in the area surrounding the drilling location, due to sudden jumping of the drill caused by the vibrations. Additionally, the controls and adjustments should be easily accessible even when drilling. The CFM value is a true indicator of the power of the air drill. Most air drills are shipped with a set of drill bits of varied sizes, ranging from around 3/64th to 3/8th of an inch. Popular manufacturers of air drills include Astro Pneumatic, Campbell Hausfeld, Chicago Pneumatic, Ingersoll Rand, and Viking.