Question

Mean diameter of conical spring is 100 mm, height of spring is 50 mm, angle between the base and slanting side of the cone is 45 degrees and diameter of the wire is 5 mm. What is the inner diameter at top edge of spring?

(a) 10

(b) 5

(c) 20

(d) 15

This question was addressed to me in homework.

This question is from Helix upon a Cone in section Curves used in Engineering Practice of Engineering Drawing

Answer 1

Correct answer is (c) 20

Explanation: Since the given angle is 45 degrees the max height of spring is equal to the radius of the base. Height given is 50 mm. Due to a diameter of wire height of helix is 45 mm. 50-45 =5 will be the radius of top end helix and due to diameter of wire the inner diameter of top end is 5 x 2 -5= 5 mm.