Question

What is a thread per inch in screw thread?

(a) Pitch in inches

(b) Axial distance moved by threaded part

(c) Reciprocal of pitch in inches

(d) Radial distance moved by threaded part

I had been asked this question by my school teacher while I was bunking the class.

The origin of the question is Screw Threads Terminology topic in chapter Metrology of Screw Thread, Gauges for ISO Metric Screw Threads of Engineering Metrology

Answer 1

Right option is (c) Reciprocal of pitch in inches

For explanation I would say: Thread per inch is the reciprocal of the pitch(inches). The angle made by the thread helix at the pitch line with plane perpendicular to the axis is known as lead angle. Lead angle is measured in an axial plane.