Thread Milling Operations

Introduction & Core Concepts

Thread milling is an advanced metal-cutting method used to generate internal and external threads using circular helical interpolation. Unlike traditional tapping, where a tool of the exact thread size is twisted into the hole under high torque, thread milling uses a smaller-diameter tool rotating at high speeds while tracing a helical path.

In Fusion 360, the Thread (or Thread Milling) operation gives programmers precise control over thread pitch, multiple radial passes, and cutter compensation. Thread milling offers distinct advantages over tapping:

• A single tool can machine a wide range of thread diameters (e.g., M12, M16, and M20) as long as they share the same pitch.
• Lower spindle torque requirements make it ideal for light-duty CNC machines.
• Broken thread mills can be easily removed, whereas a broken tap often ruins the entire workpiece.
• Threads can be cut close to the bottom of blind holes with excellent chip control.

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