Technical Drawing: Layouts and Lettering

Comprehensive flashcards covering Chapter 2: Layouts and Lettering from Technical Drawing with Engineering Graphics, 15th edition, including projection systems, alphabet of lines, scaling tools, lettering standards, drawing media, and title block layouts.

Behind every 2D drawing of an object, what three "imagined" elements make up the space relationship?

1. The observer's eye, or station point; 2. The plane of projection; 3. The projectors (also called visual rays or lines of sight).

Which projection method is illustrated in this diagram, where visual rays converge from the object toward a single station point?

Perspective projection

Which projection method is shown in this diagram, where projectors extend parallel to each other toward the plane of projection?

Parallel projection

What are the two primary classifications of parallel projection?

Oblique projection and orthographic projection.

What are the standard line measurements and dash lengths specified for a centerline?

Long dashes are $19\text{ to }38\text{ mm}$ ($0.75\text{ to }1.5\text{ in.}$), short dashes are $3.2\text{ mm}$ ($0.12\text{ in.}$), and spaces between dashes are $1.6\text{ mm}$ ($0.06\text{ in.}$).

How do short-break lines and long-break lines differ in line weight and graphic style?

Short-break lines are thick and drawn freehand (or freely drawn using CAD), whereas long-break lines are thin with sharp zigzags and drawn freehand or freely drawn.

For what technical drafting applications is the hard group of pencil leads ($9\text{H}$ to $4\text{H}$) primarily used?

They are used where extreme accuracy is required, such as on graphical computations, charts, and diagrams.

Which specific medium-grade pencil leads are widely used on pencil tracings for reproduction?

$\text{H}$ and $2\text{H}$ leads.

Why are soft pencil leads ($2\text{B}$ to $7\text{B}$) considered unsuitable for mechanical drafting?

They produce smudged, rough lines that are difficult to erase and require continual sharpening.

How is an engineers' scale (civil engineers' scale) graduated in units of 1 inch?

It is a decimal scale divided into $10$, $20$, $30$, $40$, $50$, and $60$ parts per inch.

How is the half-size scale on a mechanical engineers' scale graduated?

It is graduated so that every $\frac{1}{2}\text{ in.}$ represents $1\text{ in.}$, acting as a full-size scale compressed to half size.

When selecting architectural units and entering length values in AutoCAD software, what unit of measurement does a numerical input of $1$ represent?

One inch (not one foot).

Why do engineering drawings primarily use single-stroke sans serif lettering?

Because sans serif letters are highly legible and quick to draw.

What is the standard height for most hand-drawn and plotted CAD notes?

About $3\text{ mm}$ ($\frac{1}{8}\text{ in.}$) high.

What is the standard slope angle from the horizontal for inclined (italic) capital letters and numerals?

About $68^\circ$ from the horizontal.

What are four standard rules for lettering fractions on technical drawings?

1. Never let numerals touch the fraction bar; 2. Center the denominator under the numerator; 3. Make the fraction bar slightly longer than the widest part of the fraction; 4. Avoid using an inclined fraction bar except in narrow spaces (such as a parts list).

Why should equal mechanical distances not be used between adjacent letters in hand lettering?

Putting equal measured distances from letter to letter makes them appear unequally spaced; letters should instead be spaced by eye so that background areas between letters appear equal.

Where is the title block standardly located on a technical drawing sheet layout?

In the lower right corner of the sheet format.

What are the standard dimensions for U.S. drawing sheet sizes A and B?

Size A is $8.5 \times 11.0\text{ in.}$ and Size B is $11.0 \times 17.0\text{ in.}$

What two "spaces" does AutoCAD use to transform a full-size CAD model into proportionate views that fit on a sheet of paper?

Model space and paper space.