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creating a new threaded hole in hole wizard/toolbox customization

Question asked by Mike Russell on Jul 21, 2011
Latest reply on Jul 21, 2011 by Mike Russell

I have a question on two terms used in defining a new thread.


"Thread Minor Diameter" and "Thread Minor Diameter Inside"


The data for a 1/4-20 from the hole wizard data:


       "Thread Minor Diameter"  = 0.1905

       "Thread Minor Diameter Inside" = 0.1959


I can not find any thread data close to the numbers given above for a internal thread in any of our thread data books.


Is the "Thread Minor Diameter" the theoretical diameter for 100% full thread?


I just need to know exactly how the terms above relate to physical thread geometry.


And where I can find the data or what formulas are used to derive them.


The answer in S-04970: Thread Minor Diameter = the diameter of a cylinder formed by the roots of the threads

                                        Thread Minor Diameter Inside = the diameter of a cylinder formed by the crests of an internal thread


Is unclear at best as to how the number relate to the actual thread geometry.