ASME B [Revision of ASME B (R)] Unified Inch Screw Threads (UN and UNR Thread Form) A N A M E R I C A N N AT I O N A L STA N DA. Nominal Diameter, Major Diameter Inch, Major Diameter mm, Tapping Drill Size mm, TPI, Pitch mm. 5/16″ – 20 UNR, , , , 20, 5/16″ – IFI NOTES: 1. ASME B is a standard developed through the procedures of The This abstract presents the requirements of ASME B as they ap- ply to the.
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This is a seemingly innocuous statement, but this is where the pitch diameters change by 0. To get the complete details, buy a copy and read the Foreward. Well here we aeme in and I daily get screw thread b.1-2003 requests for the N-series thread. I expect that paragraph 8. The intention is to provide accurate information; regardless; errors may exist in the supplied information.
This statement is strong because it has been printed in the now current standard. Two basic things in B1. Standards Subscriptions from ANSI provides a money-saving, multi-user solution for accessing standards.
The seemingly random number changes hit many of the listed standard screw thread sizes. Live Chat Powered by jivochat. It informs all who make 60 degree inch screw threads that all previous versions of the standard have been as,e. Because of this, most gage makers are not moving to change to the new pitch diameters.
The N-series is fully mechanically interchangeable with the UN-series. The print requires the N-series and he does not dare deviate from the drawing. The drawings are not under his control and it takes an act of congress to get a b1.1-2003 change. Standards Subsctiption may be ssme perfect solution. The third-party inspector does not understand the finer points of subtle change over time in the screw thread standard so if it says NC-2 on the as,e, the gage had better read NC-2 or his part will get rejected.
You can download and open this file to your own computer but DRM prevents opening this file on another computer, b1.1-2003 a networked server. Several times b.1-2003 the standard they remind the reader that the N-series is mechanically interchangeable with the UN-series.
It has been over half a century and high quality ISO registered companies are still making screw threads to the long obsolete B1. Table 3B has been moved: This did not affect only the pitch diameters, but also several other unified inch screw thread dimensions throughout Table 2. How do we get the message across that when a standard changes, go with the flow and change your drawings and internal procedures to accommodate the revised version of reality?
It does not eliminate the UNS designation, but will eventually restrict their use to those willing to do the math to engineer the thread because as of the next revision of the standard the chart will disappear. Make drawing changes at the detail level of product designs.
UNR Thread ASME B1.1-2003
This is a smart move to encourage standardization. Please first log in with a verified email before subscribing to alerts. Already Subscribed to this document. After all that explaining the requestor replies that: Second, the thread nomenclature was changed from N to UN. As the voice of the U. Gage Crib Worldwide, Inc. Proceed to Checkout Continue Shopping. If the drawing change process is too daunting, issue a blanket engineering change order dictating that 60 degree inch series screw threads will be made to the most current version of B1.
There are several other changes in the standard, as would be expected. The revisions pose the risk of controversy over thread requirements and disputes over part acceptability.
UNR Thread ASME B
To purchase a copy visit an Authorized Reseller. I personally will do everything I can to eliminate the confusion which can lead to controversy.
This standard is also available to be included in Standards Subscriptions. For easy reference, a metric translation of this Standard has been incorporated as Nonmandatory Appendix C. When the drawing indicates the N-series screw thread, it is known that the thread is specified in B1.
First the pitch diameters of the threads were adjusted by 0. The customer is always right. This is something that all engineers need to address. Nonmandatory Appendices A through E contain useful information that is supplementary to the sections of this Standard.