Question

What is dedendum for external threads?

(a) Radial distance between pitch and minor cylinder

(b) Radial distance between major and pitch cylinder

(c) Radial distance between major and minor cylinder

(d) Axial distance between major and pitch cylinder

I had been asked this question in homework.

My question is taken from Screw Threads Terminology topic in division Metrology of Screw Thread, Gauges for ISO Metric Screw Threads of Engineering Metrology

Answer 1

Right option is (a) Radial distance between pitch and minor cylinder

Easy explanation: Addendum for an external thread is defined as the radial distance between the major cylinder and pitch cylinder and for internal addendum is the radial distance between the minor cylinder and pitch cylinder. Dedendum for external thread is the radial distance between the pitch cylinder and minor cylinder and this is the radial distance between the major and pitch cylinders for internal thread.