CNC turning commonly uses cutting speed, spindle RPM and feed per revolution. This reference keeps those variables separate so a lathe setup can be checked without mixing milling conventions.
Turning calculation chain
Use cutting speed and current diameter to calculate spindle RPM. Then use feed per revolution to calculate linear feed. CSS can change RPM automatically as diameter changes, subject to the machine’s maximum RPM.
Diameter changes
Because surface speed depends on diameter, a turning program that uses CSS can command different RPM values at different X positions. Review the spindle ceiling and the control’s CSS settings.
Rigidity
Part stick-out, tool overhang and workholding can dominate the stable condition. Record the physical setup with the calculated values.
Related tools
Use the Spindle Speed Calculator and Feed Per Revolution Calculator for the arithmetic.