Question

Why Wide tolerance on core diameter of internal threads is given?

(a) To prevent binding at the root of the tap

(b) To prevent binding at the crest of the tap

(c) To prevent binding at the flank of the tap

(d) To prevent binding at the face of the tap

The question was asked in an interview.

Query is from Tolerance for Screw Thread Gauges and Screw Threads in division Metrology of Screw Thread, Gauges for ISO Metric Screw Threads of Engineering Metrology

Answer 1

The correct option is (a) To prevent binding at the root of the tap

Easiest explanation: To prevent binding at the root of the tap wide tolerance on the core diameter of internal threads is given. It permits a tapping drill being used of ample size. This follows a general practice and results in a flat crest to the root of the thread.