In the last section, we saw that a combustion nail gun has two separate firing triggers. Most modern nail guns are built with similar safety catch devices, to keep people from accidentally shooting nails through the air. In the diagram below, you can see how a simple safety mechanism might work in an electric nail gun. The gun has a catch that holds the blade in place. To release the catch, you have to press the gun against something.
This sort of device may reduce the risk of certain injuries, but it is not a foolproof system. With this type of gun, carpenters tend to keep the main trigger depressed at all times, using the safety catch as the actual triggering mechanism: When they press the gun down on a surface, it automatically drives a nail in.
When you use the gun this way, it's a lot easier to accidentally fire a nail. All you have to do is press the gun barrel against your leg or bump into someone with it. Every year, hundreds of people are rushed to the emergency room with these sorts of injuries. To reduce this risk, some manufacturers build a sequential trip system into their guns. In this type of nailer, you have to release and depress the trigger every time you want to fire a nail.
No matter how a gun is designed, it should be appreciated for what it is: an extremely powerful, dangerous machine. Just like a handgun, power nailers fire projectiles at high speed -- some designs launch nails at speeds reaching 1,400 feet per second (427 meters per second).
In this case, convenience definitely comes at a price. Fumbling with a power nail gun might put you intensive care, while the worst you can expect from your old hammer is a bruised thumb.
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