5.7 VERTICAL BORING AND JIG BORING

The increased demand for accuracy in producing large parts initiated the refined development of modern vertical and jig boring machines. Although the modern CNC machining centers can handle small to medium-sized jig boring operations, very large and heavy work of high precision is done on modern CNC jig boring machines or vertical boring machines. Also, any size work which requires extreme accuracy is usually jig bored. The modern jig boring machines are equipped with high-precision spindles and x/y coordinate table movements of high precision and may be CNC machines with digital read-out panels. For a modern CNC/DNC jig boring operation, the circle diameter and number of equally spaced holes or other geometric pattern is entered into the DNC program and the computer calculates all the coordinates and orientation of the holes from a reference point. This information is either sent to the CNC jig boring machine s controller or the machine operator can load this information into the controller, which controls the machine movements to complete the machining operation.

Extensive tables of jig boring coordinates are not necessary with the modern CNC jig boring or vertical boring machines. Figures 5.38 and 5.39 are for manually controlled machines, where the machine operator makes the movements and coordinate settings manually.

Vertical boring machines with tables up to 192 in in diameter are produced for machining very large and heavy workpieces.

For manually controlled machines with vernier or digital readouts, a table of jig boring dimensional...