CNC machinist can calculate CNC machine spindle speed in imperial (english) units using this formula:

Sn = 3.82 * Sp / D;

where
Sn - CNC machine spindle speed, revolutions per minute (r/min),
Sp - peripheral speed in feet per minute (ft/min).,
D - diameter in inches (cutter diameter for milling or part diameter for turning).

To calculate the CNC machine spindle speed, enter the  peripheral speed in feet per minute and cutter diameter for milling or part diameter for turning in inches and click the CALCULATE button.

The program will calculate the CNC machine spindle speed in revolutions per minute.

   Sp =          

  D  =         

 Sn =   

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