Cutter-spline drive for portable electrical drilling assembly

A portable electrical drilling assembly configured for drilling holes in a surface of a workpiece, said drilling assembly comprising:

• a gear box comprising one or more gears contained within a gear box housing, said gear box housing remaining fixed in distance relative to the workpiece so as to define a machine height measured between a top surface of said gear box housing and the surface of the workpiece, with said gear box housing also defining a gear box height between said top surface and a bottom surface of said gear box housing;
• a feed mechanism coupled to said gear box and movable relative to said gear box between a plurality of positions including a raised position and a lowered position;
• a spindle coupled to said feed mechanism and having an outer ring portion and an inner ring portion positioned within and rotatable relative to said outer ring portion, said spindle configured to move rectilinearly toward or away from the surface of the workpiece as said feed mechanism moves between said plurality of positions with said spindle defining a spindle height between a top surface and a bottom surface and with said spindle also defining a chip clearance height between said bottom surface and the surface of the workpiece in each of said plurality of positions;
• a cutting component coupled to said inner ring portion, said cutting component having a shaft length with said cutting component defining an internal surface;
• and
• a splined shaft connected to one of said gears and rotatable when said one or more gears are rotated, wherein a length of said splined shaft along said shaft length includes a series of splines slidingly received within and engaged with said internal surface of said cutting component in each of said plurality of positions, with the rotation of said splined shaft rotating said cutting component, and with the rotation of said cutting component rotating said inner ring portion within said outer ring portion of said spindle;
• wherein a maximum stroke length of the drilling assembly is achieved when said feed mechanism is moved between said raised position and said lowered position but wherein a depth of a hole drilled within the surface of the workpiece increases in depth as said shaft length of said cutting component increases, wherein said maximum stroke length is defined by subtracting each of said gear box height, said spindle height, and said chip clearance height from said machine height when said feed mechanism is in said lowered position.

A method for drilling holes in a surface of a workpiece, said method comprising:

• positioning a drilling assembly onto the workpiece at a desired position, the drilling assembly including a gear box having one or more gears with a motor coupled to the one or more gears, a feed mechanism coupled to the gear box and movable relative to the gear box between a plurality of positions including a raised position and a lowered position, and a spindle coupled to the feed mechanism and having an outer ring portion and an inner ring portion positioned within and rotatable relative to the outer ring portion;
• coupling a splined shaft to the one or more gears, wherein a length of the splined shaft includes a series of splines;
• positioning the feed mechanism in the raised position;
• coupling a cutting component to the inner ring portion of the spindle, the cutting component including an internal surface with the internal surface defining a component cavity and with a maximum length portion of the splined shaft received within the component cavity and engaged with the internal surface of the cutting component;
• moving the feed mechanism to an intermediate position from the raised position to move the cutting component and the spindle rectilinearly toward the surface of the workpiece to position a tip end of the cutting component in contact with a surface of the workpiece while maintaining at least an intermediate length portion of the length of the splined shaft in engagement with the internal surface of the cutting component;
• activating the motor to rotate the one or more gears, wherein the rotation of the one or more gears rotates the splined shaft, wherein the rotation of splined shaft rotates the cutting component, and wherein the rotation of the cutting component rotates the inner ring portion of the spindle;
• and
• drilling a hole of a predetermined length in the workpiece by moving the feed mechanism from the intermediate position to the lowered position with the motor activated and while maintaining at least a minimum length portion of the length of the splined shaft in engagement with the internal surface of the cutting component, wherein a length of the intermediate length portion is between a length of the maximum length portion and the minimum length portion.