Quick SFM/RPM reference and calculators for milling, turning, drilling, and tapping. Starting points for common materials — always verify with your tooling manufacturer.
RPM & Feed Calculator
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SFM Reference — Starting Points for End Milling
Material
HSS SFM
Carbide SFM
Chip Load (IPT) 1/2" EM
RPM = (SFM x 3.82) / Diameter Feed Rate (IPM) = RPM x # Flutes x Chip Load
These are conservative starting points. Adjust based on rigidity, tool condition, coolant, and depth of cut.
Turning RPM & Feed Calculator
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Turning SFM & Feed Reference
Material
HSS SFM
Carbide SFM
Roughing IPR
Finishing IPR
RPM = (SFM x 3.82) / Workpiece Diameter Feed IPM = RPM x IPR
Reduce speed 10-20% for interrupted cuts. Use lower feeds for finishing to improve surface finish.
Drilling RPM & Feed Calculator
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Drilling SFM & Feed Reference
Material
HSS SFM
Carbide SFM
IPR (≤1/4")
IPR (1/4"–1/2")
IPR (1/2"–1")
RPM = (SFM x 3.82) / Drill Diameter Feed IPM = RPM x IPR
Feed per revolution is heavily dependent on drill diameter — larger drills can handle higher feed per rev. Use peck drilling for depths beyond 3x diameter.
Tapping RPM & Feed Calculator
Select a tap size and enter SFM
Tapping SFM Reference
Material
HSS Tap SFM
Carbide/Coated SFM
Notes
RPM = (SFM x 3.82) / Tap Major Diameter Feed Rate = RPM x Pitch (in/rev)
Tapping feed rate is NOT optional — it is exactly 1/TPI (or pitch for metric). Rigid tapping = RPM x (1/TPI). Floating holders add compliance but the same feed rule applies.
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