US Patent 7665540 Multistage solenoid fastening device

A method of driving a fastener into a workpiece with a tool generally includes retracting a trigger into a housing of the tool to execute a driver sequence and establishing a magnetic field in a multistage solenoid. The magnetic field is established in at least one of a first stage and a second stage. The method includes drawing an armature member to an extended condition from a retracted condition with the magnetic field and determining a position of the armature member relative to at least one of the first stage and the second stage. The method also includes directing power between the first stage and the second stage during the driver sequence based on the position of the armature member.