A machine for assembling fence panels. The machine includes rail supports, a plurality of rail transport assemblies, a picket hopper for storing pickets substantially perpendicular to the rail supports, a picket transport assembly, a picket spacing assembly, a picket skewing assembly, and nailing guns. The rail transport assemblies include a conveyor for moving rails longitudinally to an assembly position. The picket transport assembly uses a conveyor to move pickets from the hopper to the assembly position, delivering the pickets at an acute delivery angle. The picket spacing assembly increases the delivery angle for a picket to increase spacing between pickets. The picket skewing assembly pushes an end of a picket closer to a previous picket to adjust for spacing between warped pickets. The nailing guns secure a picket at the assembly position to the rails. A machine controller is used to automatically operate the components of the machine.