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Machining 4 uses Updated August 10, 2026

Lathe Cutting Time Calculator

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Enter the length of threaded portion
Enter the diameter of tap used
Pitch
Revolution of the job per minute

This lathe cutting time calculator finds the machining time for a turning or boring pass from the cut length, feed rate, and spindle speed. Enter the values above.

Formulas

Time T = L ÷ (f × N)
Spindle speed N = 1000 × Vc ÷ (π × D)
  • L — cut length, f — feed per rev, N — rpm, Vc — cutting speed, D — diameter

Example

L = 100 mm, f = 0.2 mm/rev, N = 500 rpm: T = 100 ÷ (0.2 × 500) = 1.0 min.

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Frequently Asked Questions

How do I calculate lathe cutting time?

Divide the cut length by the product of feed per revolution and spindle speed: T = L / (f x N).

How do I find spindle speed from cutting speed?

Use N = 1000 x Vc / (pi x D), with cutting speed in m/min and diameter in mm.

Does this cover multiple passes?

It gives time per pass. Multiply by the number of passes for the total roughing and finishing time.

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