IST Blueprint Reading and Technical Drawings 3

Question 1

What does the callout '4X Ø.500 ±.005' mean on a blueprint?

Accepted Answer

Four holes each with a diameter of 0.500 inches and a bilateral tolerance of ±0.005 inches

Answer

'4X' means four identical features, 'Ø' is the diameter symbol, '.500' is the nominal diameter, and '±.005' is the bilateral tolerance allowed above and below that nominal value.

Question 2

What is the purpose of a datum in GD&T (Geometric Dimensioning and Tolerancing)?

Accepted Answer

To serve as a theoretically exact reference point, axis, or plane from which measurements are made

Answer

A datum is a theoretically exact feature (point, axis, or plane) established from actual part surfaces that serves as the origin for all dimensional and geometric measurements on the part.

Question 3

What does bilateral tolerance mean?

Accepted Answer

The tolerance allows the actual dimension to vary equally in both directions from the nominal value

Answer

Bilateral tolerance (expressed as ±value) allows the actual dimension to deviate equally above and below the nominal, so a dimension of 1.000 ±.005 accepts any value from 0.995 to 1.005.

Question 4

When 'THRU' appears in a hole callout on a blueprint, what does it indicate?

Accepted Answer

The hole passes completely through the part from one surface to the other

Answer

'THRU' indicates the hole is a through-hole that penetrates completely from one surface of the part to the other, as opposed to a blind hole that stops at a specified depth.

Question 5

What does the thread callout '1/4-20 UNC' specify about a threaded hole?

Accepted Answer

1/4-inch diameter, 20 threads per inch, Unified National Coarse thread series

Answer

'1/4' is the nominal diameter in inches, '20' is the number of threads per inch, and 'UNC' stands for Unified National Coarse, a standard thread series widely used for general-purpose fastening.

IST - Industrial Skills Test Practice Test

IST - Industrial Skills Test Practice Test

IST Blueprint Reading and Technical Drawings 3