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Calcimator

Thread Milling Calculator

Calculate helical interpolation feeds, speeds, and thread geometry for CNC thread milling operations.

Inputs

in
in
in
RPM
in/tooth

Results

Helical Feed Rate

8 IPM

Time per Pass0.05 min
Thread Depth0.03 in
Minor Diameter0.44 in
Threads per Inch20 TPI
Z Feed Per Rev$0.05
How to Use This Calculator
  1. Enter the major thread diameter and thread pitch (or TPI) for the required thread specification.
  2. Set the thread mill cutter diameter, spindle RPM, chip load per tooth, and flute count.
  3. Review helical feed rate, time per threading pass, thread depth, and minor diameter.
  4. Program a single helical interpolation pass using the calculated feed rate and thread depth.

How the result changes with Thread Mill Diameter

Thread Mill DiameterHelical Feed Rate
0.655.4 IPM
2.1318.4 IPM
3.9220.9 IPM
5.4121.8 IPM

What each input means

Major Thread Diameter
Nominal thread major diameter.
Thread Pitch
Thread pitch (1/TPI). For 20 TPI, enter 0.05.
Thread Mill Diameter
Diameter of the thread milling cutter.
Spindle RPM
Spindle speed for the thread milling operation.
Chip Load
Recommended chip load per tooth for thread milling.
Number of Flutes
Number of cutting edges on the thread mill.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Major Thread Diameter = 0.5, Thread Pitch = 0.05, Thread Mill Diameter = 0.375, Spindle RPM = 4000 = 6 input(s) provided
  2. Calculate Helical Feed Rate
    8 = 8
  3. Calculate Time per Pass
    Time per Pass
    0.049 = 0.049
  4. Calculate Thread Depth
    Thread Depth
    0.0307 = 0.0307

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