Threads & tolerances
Published on Sunday, 09. January 2005
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Content Guide：Below is an example of a common CNC thread and tolerance requirement table for reference
Below is an example of a common CNC thread and tolerance requirement table for reference:
Thread Type | Thread Specification | Tolerance Grade | External Thread Tolerance | Internal Thread Tolerance | Remarks |
|---|---|---|---|---|---|
Metric Thread | M6x1 | 6g | -0.028 to -0.148 mm | - | Suitable for general fasteners |
M8x1.25 | 6H | - | +0.025 to +0.140 mm | Suitable for internal threads | |
M10x1.5 | 6g | -0.032 to -0.172 mm | - | Suitable for external threads | |
Imperial Thread | 1/4"-20 UNC | 2A | -0.0014 to -0.0055 inch | - | Suitable for external threads |
1/2"-13 UNC | 2B | - | +0.0014 to +0.0055 inch | Suitable for internal threads | |
Pipe Thread | G1/8" | B | -0.014 to -0.034 mm | - | Suitable for external threads |
G1/4" | A | - | +0.010 to +0.030 mm | Suitable for internal threads | |
Trapezoidal Thread | Tr20x4 | 7e | -0.050 to -0.200 mm | - | Suitable for power transmission threads |
Tr30x6 | 7H | - | +0.050 to +0.200 mm | Suitable for internal threads |
Thread Type: Common thread types include metric threads, imperial threads, pipe threads, and trapezoidal threads.
Thread Specification: Indicates the thread size and pitch, e.g., M6x1 represents a metric thread with a diameter of 6mm and a pitch of 1mm.
Tolerance Grade: Indicates the precision grade of the thread, such as 6g, 6H, 2A, 2B, etc.
External Thread Tolerance: Applicable to the dimensional tolerance range for external threads.
Internal Thread Tolerance: Applicable to the dimensional tolerance range for internal threads.
Remarks: Provides explanations for the application scenarios or special requirements of the threads.
Tolerance values may vary depending on the standard (e.g., ISO, DIN, ANSI, etc.).
Actual machining requires adjusting tolerances based on specific drawing requirements and material properties.
The selection of thread tolerances should consider assembly requirements and functional needs.
If a more detailed table or tolerance data for specific standards is needed, please provide additional information.
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