• Thread Form - the outline of the thread, for example 8 Round or Buttress. Our example is an 8 Round.
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Pitch Line - imaginary line that runs through the thread where the distance between parallel sides of the profiles of two adjacent thread forms is measured along the axis.

• Crest – the peak or top of the thread that joins the sides of two adjacent flanks.
• Root – the bottom of the thread valley or the bottom surface joining the sides of two adjacent flanks.
• Included Angle – the angle between the thread flanks as measured perpendicular to the thread axis.
• Stab Flank – the side of the thread that takes the initial force when a pin and coupling are tightened.
• Load Flank – the side of the thread that absorbs the surface load as the pin and coupling are tightened.