Portable boring bar apparatus

A boring bar apparatus for boring an opening through a workpiece centered with respect to a pilot hole of the workpiece, comprising:

• an elongate cylindrical boring bar adapted to extend through said pilot hole, said boring bar having an outboard portion in which is supported a rotary cutting tool for boring the opening in the workpiece;
• a drive apparatus receiving an inboard portion of said boring bar for rotating and axially translating the boring bar to bore the opening in the workpiece with the cutting tool;
• a workpiece mounting arm adapted to be welded to the workpiece;
• a drive apparatus support arm for supporting the drive apparatus and the boring bar, said drive apparatus support arm having an inboard end including a bearing rotatably supporting said boring bar and an outboard end extending radially beyond the drive apparatus for attachment to said workpiece mounting arm;
• and
• a set-up support arm temporarily attached to said workpiece mounting arm, said set-up support arm being identical to the drive apparatus support arm, whereby once said set-up support arm is positioned so that its bearing is centered with respect to said pilot hole, and said workpiece mounting arm is welded to the workpiece, said outboard end of said drive apparatus support arm is attached to said workpiece mounting arm in place of said set-up support arm.