Question

How is a spot face hole with 24mm diameter, 5mm deep and spot face diameter 10mm dimensioned?

(a) Φ24 and φ10

(b) 5 SPOT FACE, φ24 X φ10

(c) φ24 SPOT FACE, φ10

(d) φ10 SPOT FACE, φ24 x 5 DEEP

I have been asked this question in an interview for internship.

This is a very interesting question from Basic Principles in Dimensioning -1 in section Lines, Lettering and Dimensioning of Engineering Drawing

Answer 1

The correct answer is (d) φ10 SPOT FACE, φ24 x 5 DEEP

Easy explanation: Holes made by spot facing are dimensioned in this manner ‘φ10 SPOT FACE, φ24 x 5 DEEP’. This means the there is a spot face of 10mm diameter after the 24mm diameter and 5 mm thickness. Using this makes the reading of the dimension easy.