Tapping

Tap cycles are similar to simple drill cycles except the feed and speed are coordinated to properly match the thread lead. CAD/CAM software calculates the feed according to the cutting speed and threads per inch (TPI) of the tap.

Figure 7.16: Tapping

Rules for Tapping

• Use the drill chart in Appendix F to find the correct drill diameter for cutting taps. Use the manufacturers recommended drill size for form taps.

• Consider brushing on tapping fluid instead of using coolant for small tapped holes to help prevent the tap from breaking.

• Tapped holes smaller than about #8 can be difficult to create on the machine without breaking the tap. Consider tapping these holes by hand rather than on the CNC.

• If the machine does not support Rigid Tapping, a floating tap holder is required to tap. Refer to the tapping head documentation for proper use.

• Be sure to specify a tip depth sufficient to account for the tip and initial taper of the tap.

• Older machines may require a larger feed height to allow the machine spindle to reach full speed before the thread engages the material.