A compressed air nailer or stapler has two positions – idle and activated, or ‘not fired’ and ‘fired’ if you prefer to think about it that way.

It’s useful to understand what is happening in terms of the compressed air inside the tool in either position, in order to be able to use it at an expert level.

To begin with, in the idle position, compressed air is able to flow into the main body of the nailer or stapler through the connection at the back of the tool.

It also typically passes into the inner trigger module too, forcing the bottom disk of the firing valve down to prevent air from entering the main cylinder sleeve.

Significantly, the driver or piston assembly is up at this point, waiting for its next downward stroke, while return air pressure is able to escape if necessary.

When the trigger is pulled, compressed air is exhausted from the firing valve assembly, while air rushes into the main cylinder sleeve, forcing the piston down quickly.

The return air chamber fills once the piston has fired and, once the trigger is released, this allows the piston to be forced back up to the idle position, ready for the next stroke.