About Machining Spindle RPM & Cutting Speed Calculator
Calculate optimal CNC milling, lathe turning, and drilling spindle RPM based on tool diameter and material surface cutting speed (Vc in m/min or SFM). Also calculates milling table feed rates (mm/min) and electric motor synchronous speeds.
Key Capabilities & Features
- Calculates spindle RPM from tool diameter and cutting speed: N = (1000 · Vc) / (π · D)
- Simultaneous metric cutting speed (m/min) and Imperial Surface Feet per Minute (SFM)
- Milling table feed rate calculation based on chip load per tooth and flute count
- AC induction motor synchronous speed calculator for 2, 4, 6, and 8 pole motors at 50Hz/60Hz
- Presets for common cutting tool and workpiece combinations
How to Use Machining Spindle RPM & Cutting Speed Calculator
Select Calculation Mode
Choose CNC Machining Cutting Speed or AC Induction Motor Speed.
Enter Tool Geometry & Speed
Specify endmill/part diameter (mm) and recommended surface cutting speed (Vc).
Obtain Spindle Speed & Feed
Set your CNC controller to the calculated spindle RPM and table feed rate.
Privacy & In-Browser Execution Guarantee
100% local workshop calculation without cloud dependencies.
Frequently Asked Questions
What is the formula for cutting speed (Vc) to RPM?
In metric units: Spindle RPM = (1000 × Vc) / (π × Tool Diameter in mm). In Imperial units: Spindle RPM = (3.82 × SFM) / Tool Diameter in inches.
Why does synchronous motor speed differ from nameplate RPM?
Synchronous speed Ns = (120 × f) / p is the rotational speed of the stator magnetic field. Induction motors experience 2-5% rotor slip under load, resulting in nameplate ratings of 1750 RPM for 1800 RPM synchronous motors.