A method of manufacturing a crankshaft includes the steps of: (1) forming a crankshaft blank via a first half and a second half; (2) measuring a plurality of surface variations between a predetermined surface in a first region and a corresponding predetermined surface in a second region of the crankshaft blank; (3) calculating centering offset data based on the plurality of surface variations; (4) machining a pair center holes based on the centering offset data; (5) machining a counterweight and a journal relative to the pair of center holes to produce a partially machined crankshaft; (5) milling and grinding the partially machined crankshaft to produce a finished machined crankshaft; and (6) rotating the finished machined crankshaft typically on the outermost main journals in a final balancing machine and then modifying the counterweights to eliminate undesirable vibration generated during the rotation and engine operation.

A method of manufacturing a crankshaft includes the steps of: (1) forming a crankshaft blank via a first half and a second half; (2) measuring a plurality of surface variations between a predetermined surface in a first region and a corresponding predetermined surface in a second region of the crankshaft blank; (3) calculating centering offset data based on the plurality of surface variations; (4) machining a pair center holes based on the centering offset data; (5) machining a counterweight and a journal relative to the pair of center holes to produce a partially machined crankshaft; (5) milling and grinding the partially machined crankshaft to produce a finished machined crankshaft; and (6) rotating the finished machined crankshaft typically on the outermost main journals in a final balancing machine and then modifying the counterweights to eliminate undesirable vibration generated during the rotation and engine operation.

A center for use on a tailstock of a lathe is disclosed. The center comprises an elongated shaft having a proximal end to be secured in a tailstock of a lathe, and a distal end that includes a conical tip for insertion into a center hole in a workpiece. The center also comprises a pivotable arm having a proximal arm end that is rotatably and slidingly secured to the elongated shaft. The pivotable arm has a distal arm end that is rotatable into a position atop the conical tip. The distal arm end has a distal side that includes a center drill, and a proximal side that includes a recess that is seatable onto the conical tip. The conical tip and the center drill have the same rotational centerpoint when the distal arm end is positioned over the conical tip and the conical tip is placed within the recess.

A rotary tool can be adapted for removing material from a workpiece such as a lower receiver. A rotary tool can have an adapter with a major diameter, and a cutter head with a minor diameter. The major diameter of the adapter can reduce deflection and chatter, while the minor diameter of the cutter head can be used to manufacture lower receivers with accuracy. The rotary tool can be adapted to be engaged with a rotary power tool.

A rotary tool can be adapted for removing material from a workpiece such as a lower receiver. A rotary tool can have an adapter with a major diameter, and a cutter head with a minor diameter. The major diameter of the adapter can reduce deflection and chatter, while the minor diameter of the cutter head can be used to manufacture lower receivers with accuracy. The rotary tool can be adapted to be engaged with a rotary power tool.

A method and apparatus for center height alignment of a boring bar is disclosed. The apparatus includes a seat member with a bottom and a back, and a digital angle gauge mounted to the seat member. The method includes the steps of: assembling an apparatus comprising a seat member and a digital angle gauge; calibrating the apparatus such that a Display of the digital angle gauge reads zero degrees; and aligning the center height of the boring bar by rotating the boring bar such that the Display of the digital angle gauge reads zero degrees when the apparatus is mounted onto the boring bar.

A method and apparatus for center height alignment of a boring bar is disclosed. The apparatus includes a seat member with a bottom and a back, and a digital angle gauge mounted to the seat member. The method includes the steps of: assembling an apparatus comprising a seat member and a digital angle gauge; calibrating the apparatus such that a Display of the digital angle gauge reads zero degrees; and aligning the center height of the boring bar by rotating the boring bar such that the Display of the digital angle gauge reads zero degrees when the apparatus is mounted onto the boring bar.

A crankshaft machining system includes a center hole boring device, a post-centering balance meter and a cutting device. The post-centering balance meter is configured to measure the shape of a post-centering crankshaft blank on the basis of a pair of center holes. Additionally, the post-centering balance meter is configured to set a principal axis of inertia on the basis of the shape of the post-centering crankshaft blank and generate center hole positional information for correction that indicates intersections between the principal axis of inertia and both end surfaces of the post-centering crankshaft blank. The center hole boring device is configured to bore a pair of center holes on both end surfaces of another crankshaft blank to be loaded next on the basis of the center hole positional information for correction.

A crankshaft machining system includes a center hole boring device, a post-centering balance meter and a cutting device. The post-centering balance meter is configured to measure the shape of a post-centering crankshaft blank on the basis of a pair of center holes. Additionally, the post-centering balance meter is configured to set a principal axis of inertia on the basis of the shape of the post-centering crankshaft blank and generate center hole positional information for correction that indicates intersections between the principal axis of inertia and both end surfaces of the post-centering crankshaft blank. The center hole boring device is configured to bore a pair of center holes on both end surfaces of another crankshaft blank to be loaded next on the basis of the center hole positional information for correction.

A pocket hole jig includes base with a base plate and first and second lateral side walls extending along the base plate, and a body disposed between the first and second lateral side walls and slidable along the base in a forward direction and a rearward direction. The body includes a drill bit aperture angled downward toward the base plate. The pocket hole jig also includes a fence movable between a raised position and a lowered position and having a contact surface engageable with an end of the workpiece when the fence is in the lowered position to position the base a predetermined distance from the end of the workpiece. The contact surface is in a first position when the fence is in the raised position and a second position when the fence is in the lowered position. The second position is forward of the first position.