What does the "J" in thd description stand for?
What does the "J" in thd description stand for?
(OP)
1.125-18 UNJEF-3B is the thd call out, does anyone know what the "J" stands for.
Thanks Bodie
Thanks Bodie
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What does the "J" in thd description stand for?
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RE: What does the "J" in thd description stand for?
http://euler9.tripod.com/bolt-database/23.html
http://assist.daps.dla.mil/eAccess/index.cfm?ident...
MIL-S-8879
hope this is some help
ctopher
RE: What does the "J" in thd description stand for?
There is only two ways to inspect this feature on an internal thread either sectioning the part and using a optical comparator or using some expansion foam or clay and filling the thread form and removing the resultant form and checking the root radius.
I assume this thread form is used to reduce the stress riser at the root of the thread. I personally do not think this thread form has much impact on the servicability of the part but if its on the print you should try to conform.
If the part is manufactured on a lathe the threading tool will need to have the proper radius however, if this is tapped, a special tap will be required.
Good Luck
RE: What does the "J" in thd description stand for?
The "J" thread form is a modified thread form with a controlled, tangent root radius on the external thread, and an increased minor diameter on external and internal threads. It is usually specified in aerospace of in fatigue critical applications.
The sole modification to the internal thread form/dimensions (when compared to a “standard”, “non-J” thread) is a small increase in the thread minor diameter (the “pre-tap” or “pre-thread-cutting” diameter) to prevent interference of the radiused external thread root with the internal thread.
Example: The minor diameter of your 1.125-18 UNJEF-3B thread should be 1.0784/1.0709, where the minor diameter of a 1.125-18 UNEF-3B thread is 1.0730/1.0650.
UNJ internal threads can be inspected with standard threaded plug gages (of the appropriate class). The (modifed) minor diameter is inspected with a gage of the apporpriate size, or directly measured to the applicable requirements.
RE: What does the "J" in thd description stand for?
RE: What does the "J" in thd description stand for?
Chris
Sr. Mechanical Designer, CAD
SolidWorks 05 SP3.1 / PDMWorks 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716
RE: What does the "J" in thd description stand for?
Root Radius: 0.0063 TO 0.00752