Power tool plastic gear train

In a power tool including a housing and a motor mounted in the housing and having a pinion gear, a gear train assembly comprising:

• a non-metallic cylindrical ring gear adapted to be fixed to the motor in coaxial surrounding relationship with the pinion gear, a non-metallic carrier frame disposed within said ring gear, said carrier frame having a hollow shaft portion coaxially receiving the pinion gear therein, at least one non-metallic planet gear, at least one pin engaged with said frame and rotatably supporting said planet gear for meshing engagement with the pinion gear and with said ring gear, bearing means fixed in said ring gear and rotatably supporting said carrier frame within said ring gear, and a metal output shaft having a circumferential groove formed therein, said groove having a first side wall and a second side wall and a bottom wall with one of said side walls defining a stop surface, said carrier frame being insert molded on one end of said shaft and filling said groove during said insert molding and defining a portion bearing against said stop surface to resist axial movement of said carrier frame relative to said shaft, said one end of said shaft having first splines thereon with spaces therebetween, said carrier frame filling said spaces during said insert molding to form second splines, said first and second splines cooperating to prevent relative rotation between said carrier frame and said shaft about the axis thereof.