CAD CAD Specialist Mechanical Design and Manufacturing 2

Question 1

What is the purpose of a 'datum' in GD&T on a mechanical drawing?

Accepted Answer

A theoretical exact point, line, or plane used as the reference for measurements and tolerances

Answer

A datum is a theoretically exact reference (point, axis, or plane) from which geometric tolerances and measurements are established.

Question 2

In mechanical CAD, what does the 'first angle' projection method indicate about view arrangement?

Accepted Answer

The object is between the observer and the projection plane, used predominantly outside the US

Answer

First angle (ISO) projection places the object between the observer and the plane, resulting in view layouts opposite to the US third-angle standard.

Question 3

What does the term 'feature of size' mean in GD&T?

Accepted Answer

A geometric shape defined by a single size dimension, such as a hole diameter or slot width

Answer

A feature of size is a geometric feature (like a hole, pin, or slot) that can be defined by a single size dimension and has an axis or center plane.

Question 4

Which file format is the universal neutral format for exchanging 3D CAD data between different mechanical CAD software packages?

Accepted Answer

.STEP (STP)

Answer

STEP (Standard for the Exchange of Product model data) is the neutral ISO 10303 format used to exchange 3D CAD models across different software.

Question 5

In a mechanical assembly, what is an 'interference fit' (also called a press fit)?

Accepted Answer

A fit where the shaft is larger than the hole, requiring force to assemble

Answer

An interference fit has a shaft diameter larger than the hole diameter, requiring press-fitting or shrink fitting to assemble.

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