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

Four lines each 0.500 inches in length with a total variation of 0.005 inches

Answer

A single hole 4 times 0.500 inches in total depth

Answer

Four flat surfaces each 0.500 inches thick

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

To mark the location where material should be cut away

Answer

To indicate the part number assigned by the engineering department

Answer

To show the direction of the machining feed during manufacturing

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

The tolerance applies in only one direction — either above or below — the nominal value

Answer

Two separate engineers independently set the tolerance range

Answer

The tolerance applies to both mating parts simultaneously

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

The hole has internal threads cut through its full depth

Answer

The hole requires a through-hardened surface treatment

Answer

The measurement is taken through to the hole centerline

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-inch depth, 20 degrees of thread angle, Ultra Narrow Cut standard

Answer

1/4-inch pitch, 20 mm diameter, Universal Non-Circular thread

Answer

1/4-inch length, 20 threads total, United Nations Certified standard

Question 6

What is the difference between first-angle and third-angle projection in technical drawings?

Accepted Answer

First-angle (European) places views on the far side of the object from the observer; third-angle (US standard) places views on the near side

Answer

First-angle is used only for cylindrical parts; third-angle is used for flat parts

Answer

First-angle uses dashed lines for all hidden features; third-angle uses solid lines

Answer

First-angle projection is used only for section views; third-angle is used for detail views

Question 7

On a blueprint, what does the depth symbol (↧) indicate when it appears in a hole callout?

Accepted Answer

The required depth the hole must be machined into the material

Answer

The minimum wall thickness required below the hole

Answer

The depth of the surface finish treatment

Answer

The length of the fastener that will be inserted into the hole