The double-threaded screw is made to rotate one complete rotation

the-double-threaded-screw-is-made-to-rotate-one-complete-rotation

The double-threaded screw is made to rotate one complete rotation the screw advanced to 10 mm. Lead (pitch of helix) is given as 10 mm. The pitch of the screw is ____

A. 10 mm

B. 5 mm

C. 1 mm

D. 12 mm

The question was asked in an interview for job.

This intriguing question comes from Construction of Screw Threads topic in division Curves used in Engineering Practice of Engineering Drawing

Correct option is B. 5 mm

Explanation: In a double –threaded screw, the lead = the pitch of helix = 2 times of pitch of the screw. The pitch of screw = 10mm / 2 =5 mm. Even if the single- threaded screw is changed to double threaded screw the cross-section of thread and pitch of screw won’t change.