GB/T 20330-2006
Drill diameter for use prior to tapping screw threads (English Version)
- Standard No.
- GB/T 20330-2006
- Language
- Chinese, Available in English version
- Release Date
- 2006
- Published By
- General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China
- Latest
- GB/T 20330-2006
- Scope
- This standard specifies the diameter of twist drills for drilling holes before tapping for taps of normal screw-in length. The diameter of the twist drill is approximately equal to the nominal diameter (major diameter) of the thread minus the pitch. The listed drill sizes are applicable to the following threads: ——Common thread (coarse and fine thread series) of GB/T 193-2003: Table 1 and Table 2; ——Inch thread of ISO 263-1973 (UNC and UNF) ; Table 3 and Table 4; - GB/T 7306.1-2000 and GB/T 7307-2001 pipe thread: Table 5 and Table 6.
GB/T 20330-2006 history
- 2006 GB/T 20330-2006 Drill diameter for use prior to tapping screw threads
