I believe there is a mistake in that selection in that I cannot find any reference to a "UNC" (Unified National Coarse standardized thread) measuring any fraction less than 1/4" or 0.250" diameter. I believe it is some foreign (meaning some company that is not following the standards) invention that does not really exist.
From Wikipedia:
"Designation
The standard designation for a UTS thread is a number indicating the nominal (major) diameter of the thread, followed by the pitch measured in threads per inch. For
diameters smaller than 1⁄4 inch, the diameter is indicated by an integer number defined in the standard; for all other diameters, the inch figure is given.
This number pair is optionally followed by the letters UNC, UNF or UNEF (Unified National) if the diameter-pitch combination is from the coarse, fine, or extra fine series, and may also be followed by a tolerance class.
Example: #6-32 UNC 2B (major diameter: 0.1380 inch, pitch: 32 tpi)"
<end quote>
This has also been my experience over years of actually working in the fastener industry.
Put more simply, I thinks whats ya' gots dere is 'some guy's' imaginary version of a "standard" thread that is neither standard or even in use anywhere.
Brown and Sharpe (machine tool and measuring instrument Co. located in RI and an industry leader) used to make up their own threads, such as 17 1/2 TPI, but they were not standardized threads, rather a deviation from <any> standard to force a machine owner to purchase ONLY B&S hardware going forward. As you spec. sheet calls out "UNC", this would indicate a true, unified, standardized thread but I can not find any reference to any such thread. Such my thought that it is either some type of linguistic translation mistake, or a thread made up on the fly from someone's fertile imagination. At any rate, I betcha' you have several life- time supplies of rivets for screws you will never actually see and / or find. :-)
Brian
No, the set I purchased had those (#8) as well, and using a thread checker, the 5/32-32 would go loosely onto a 6-32 and only just start on a 8-32 but not go all the way on it.
I also found it strange that the rivet size for the 5/32"-32 was larger than for the 8-32 even thought the major diameter would be smaller.
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I'm beginning to think that the 5/32-32 is a Whitworth cap screw size possibly out dated, as I'm told it's listed in a 1957 version of Machinery's Handbook, but I couldn't find it in my '66 edition. Maybe if I reach down into the cushions of my sofa I'll find an earlier edition?