JIG BORING The jig boring machine is the most accurate of all machine tools. This was first developed in the year 1910 in Switzerland and used as a locating machine. The real jig borer was first built in the year 1917 by Pratt and Whitney 1. Spindle head 2. Quill 3. Column 4. Spindle housing 5.7. Spindle 6. Table 8. Bed Jig boring machines are now used for production of jigs, fixtures, tools and other precision parts which   require   high degree of accuracy. They are characterized- by provisions of highest accuracy through rigidity, low thermal expansion and precise means of measuring distance for accurately locating and spacing holes. The machining accuracy is very high, within a range of 0.0025 mm. A jig boring machine resembles in, appearance to a vertical milling machine, but so far its operation and accuracy are concerned there cannot be any comparison between the two. The -spindle and other parts of the machine are extremely rigid to, resist deflecti...