Question

Base diameter of conical helix is 80 mm, height of spring is 30 mm, angle between the base and slanting side of cone is 45 degrees and diameter of wire is 4 mm. What is the outer diameter at a top edge of spring?

(a) 14

(b) 24

(c) 32

(d) 18

This question was posed to me in an internship interview.

The query is from Helix upon a Cone topic in division Curves used in Engineering Practice of Engineering Drawing

Answer 1

The correct answer is (c) 32

To explain: Since the given angle is 45 degrees the max height of helix is equal to the radius of the base. Height given is 30 mm due to wire diameter the total helix height will be 26. 40 -26 =14 will be the radius of top end helix and due to the diameter of wire the outer diameter of top end is 14 x 2 + 4= 32 mm.