I was eyeballing a project that I am going to have to retap something 1/8 NPT, grabbed my tap and die set and it dawned on me how small 1/8" actually is... when I measure a 1/8 fitting, it's actually more like 25/64 on the outside of the threads. Even measuring the inner diameter of a fitting, it's 1/4"? Perhaps this is a question, but where does the 1/8" come into play? On the same subject, what size tap would I use to tap a hole for a 1/8 fitting to screw into?