Graded Pitch 1

[TangoCleveland]

I've seen UNC threads described as "graded pitch" threads. What is a graded pitch thread?

 

[vonlueke]

OhioLarry: The first thing that came to my mind is this might be a bungling of the term "constant-pitch series" threads, but I could be wrong. Constant-pitch series threads, as the name implies, have a constant pitch for the threads on all bolts throughout that series, regardless of bolt diameter; and are normally available only in larger diameters, say 25 mm and above.

 

[Kenneth]

The "grades" are in fact the "standard" pitch/diameter series combination designations. The "graded" pitches are Coarse ("UNC&quot, Fine ("UNF&quot and Extra Fine ("UNEF&quot, as opposed to the "constant" pitch series described by vonlueke, which are called out by the thread per inch numerical value and a "UN" callout, but without a "grade" (C, F or EF) designation.