Metric thread
Feed F in mm/min equals speed S multiplied by pitch P in mm/rev. Example: 500 rev/min × 1.5 mm = 750 mm/min.
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CNC tapping calculator
Calculate synchronized tapping feed, convert pitch and TPI, and check the practical values needed to prepare an operation.
Metric threadsUNC / UNF threadsFeed and travel timeNo data upload
How it works
How is tapping feed selected?
In synchronized tapping, axis feed must match thread pitch for every spindle revolution. The calculator preserves this relationship and presents values in both metric and imperial units.
Imperial thread
For TPI, feed in inches per minute equals spindle speed divided by threads per inch. The result is also converted to millimetres.
Drill and time
Tap-drill size is a quick approximation and time is theoretical. Both are planning aids and require process verification.
FAQ
Frequently asked questions
How is tapping feed calculated?
For a metric thread, multiply spindle speed by pitch. For an imperial thread, divide spindle speed by TPI to get inches per minute.
How do I convert TPI to millimetre pitch?
Divide 25.4 by TPI. For example, 20 TPI corresponds to a 1.27 mm pitch.
Does the calculator support left-hand threads?
Yes. Hand is included in the configuration and copied results. It does not change absolute pitch or feed; spindle direction and cycle must be configured for the machine control.
Is the tap-drill result a final selection?
No. Nominal diameter minus pitch is an approximation. Final selection depends on material, tap type, tolerance, desired thread percentage and manufacturer recommendations.
Is any data sent to a server?
No. Calculations run locally. Shared settings are stored after the # character and are not sent as part of a server request.
Custom tools
Need a calculator, macro or postprocessor tailored to your machine?
NCTune develops postprocessors, automation and dedicated tools for Siemens NX CAM and production environments.