ANSI B1.1

Unified Inch Screw Threads (UN and UNR Thread Form)

An American National Standards Institute Standard. This Standard specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads. (In order to emphasize that unifiedscrew threads are based on inch modules, they may be denoted unified inch screw threads.) Several variations in thread form have been developed for unified threads; however, this Standard covers only UN and UNR thread forms.

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