Question

What is the accuracy of top and supporting surface of type 3 precision polygon as per IS: 6987-1973?

(a) 0.005 and 0.04 mm

(b) 0.0025 and 0.005

(c) 0.007 and 0.0035

(d) 0.001 and 0.002 mm

The question was asked in an interview for internship.

This interesting question is from Precision Polygons topic in portion Angular Measurement and Circular Division of Engineering Metrology

Answer 1

The correct choice is (a) 0.005 and 0.04 mm

Best explanation: The top surface and supporting surface are made flat and parallel to accuracies of 0.0025 and 0.005 mm for type-1 and 0.007 mm and 0.0035 for type-2, 0.005 and 0.04 mm for type-3 and departure from flatness is permissible in concave direction only.