Copyright Goodheart-Willcox Co., Inc. 202 CNC Manufacturing Technology Unlike the other canned cycles in which the tool will then rapid out, the tool will exit the hole at the feed rate in a G85 cycle. Note that some small amount of material will be removed on the exit move because of the reduced tool pressure. This cycle will give the best surface finish. G0 G90 G54 X1. Y1. M03 S700 (X1. Y1. is location of first hole) G43 H1 Z1. M8 G0 Z.25 G99 G85 Z−1. R.1 F5. X2. Y2. (Second hole) X3. Y3. (Third hole) Explanation of cycle: ■ G99: Returns to reference return position (.1″ in this case) between holes. ■ G85: Turns on fine boring cycle. ■ Z: Final depth of hole. ■ R: Reference return plane. ■ F: The feed rate while boring, usually slower for boring tools. 9.8.7 G86 Cycle (Spindle Stop Boring Cycle) The G86 cycle is also used when boring or reaming holes. The tool will be positioned over an existing hole and feed down to the final Z depth. Unlike the other canned cycles, the spindle will stop at final Z depth and the tool will rapid out. Note that this can create a small scratch in surface finish as the tool drags out of the hole. This cycle will usually be performed for rough or semi-finish operations, as it is faster than G85. G0 G90 G54 X1. Y1. M03 S700 (X1. Y1. is location of first hole) G43 H1 Z1. M8 G0 Z.25 G99 G86 Z−1. R.1 F5. X2. Y2. (Second hole) X3. Y3. (Third hole) Explanation of cycle: ■ G99: Returns to reference return position (.1″ in this case) between holes. ■ G86: Turns on spindle stop boring cycle. ■ Z: Final depth of hole. ■ R: Reference return plane. ■ F: The feed rate while boring, usually slower for boring tools. 9.9 Tool Setting To this point, this chapter has addressed how to plan a program, analyze a print in depth, determine the best workholding option, and create a pro- gram. It is time to load the program into the machine and assemble the