Negative rake angle shims are required when using right-hand tools to cut left-hand threads and left-hand tools to cut right-hand threads.

High flexibility; the same insert can be used for different pitches, provided the thread profile angle (60° or 55°) and radius are the same.

V-profile inserts do not cut the thread crest. Therefore, the screw's outer diameter and the nut's inner diameter must be turned to the correct diameter before threading.

Note: Leave an extra allowance/material of 0.05-0.07 mm (0.002-0.003 inches) on the workpiece to ensure the final threading process can finish to the crest.

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Adequate space must be left behind the last thread to allow the final tooth of the insert to pass through, achieving full thread depth.

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There are three common types of inserts for threading on CNC lathes: full-profile, V-profile, and multi-tooth inserts. Each type has its advantages and disadvantages.

When performing threading on a CNC lathe, it is crucial to select the most suitable threading inserts for your application based on the insert type, flank/radial clearance, and insert profile. These factors significantly impact chip control, insert wear, tool life, and thread quality.

After selecting the appropriate insert for a CNC lathe, choosing the right insert shim is essential. Insert shims provide different inclinations, making the insert rake angle (λ) equal to the thread's helix angle. Refer to the table below for selecting the correct insert shim.

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Multi-tooth inserts are similar to full-profile inserts but have multiple cutting edges (NT > 1). A double-edged insert can double productivity, a triple-edged insert can triple it, and so on.