As a general rule at work, we always use the following to determine feed and speed for taps.... Feed always equals 9.9ipm and RPM is 10 times the pitch.
So for a 1/2-13 tap, we would use 9.9ipm and 130RPM. In some instances we will use a dividing/multiplying factor. Sometimes slower for hard metal and faster for soft metal. But make sure you multiply/divide both RPM and feed (for example - 19.8ipm and 260RPM for a 1/2-13 tap, or 4.95ipm and 65RPM for titanium). Dividing is only done when problems with breakage can't be remidied by other means.
Make sure to use tapping fluid. Coolant will somtimes work on aluminum, but any hard metal really should use a dedicated tapping fluid. |