Threads & tolerances

Published on Sunday, 09. January 2005

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.

Tagged: Threads

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