ME 159 Technical Drawing - Unit 1: Introduction to Technical Drawing

Flashcards covering foundational technical drawing definitions, ISO/BS drawing standards, hardware requirements, sheet sizes, scale calculations, drawing techniques, and line classifications.

How is "visualisation" defined in technical drawing?

Visualisation is the ability to create and manipulate images, which are visualized by describing the object's geometric elements (surfaces, edges, vertices, and curves) and how they are related.

How is "geometry" defined in the context of drawing?

Geometry is a branch of mathematics that studies the sizes, shapes, positions, angles, and dimensions of objects.

What is the formal definition of technical drawing?

Technical drawing is a formal and precise way of communicating information via drawing about the shape and size of features and precision of physical objects. It serves as a universal language of Engineering used in the design process for solving problems, visualizing objects, and conducting analysis.

What are the two major aspects of technical drawing?

The two major aspects are Concepts / Principles and Creation techniques.

Which three categories of rules govern technical drawing concepts and principles?

Technical drawing is governed by Standards, Codes, and Conventions.

What are the four levels of technical drawing standards and their corresponding examples?

1. Local standards: Format proposed by COE
2. National standards: BS
3. Regional standards: ECOWAS format
4. International standards: ISO format

How is a newly established ISO standard designated?

It is designated by the format ISO XXXX:YEAR, where XXXX stands for the number allocated to the standard and YEAR stands for the year of publication.

What are the official national standards organizations for the UK, USA, Germany, and Japan?

• UK: BS (British Standards Institute)
• USA: ANSI (American National Standards Institute)
• Germany: DIN (Deutsches Institut fuer Normung)
• Japan: JIS (Japanese Industrial Standards)

Under what condition does a technical drawing become a legally binding specification?

Only when the governing rules (standards, codes, and conventions) are understood and implemented.

How is engineering drawing grouped based on principles?

• Fundamental: Geometric Drawing
• Specialised: Mechanical Engineering Drawing, Civil Engineering Drawing, and Electrical & Electronics Engineering Drawing

What are the two categories of CAD software listed, along with their examples?

• 3D Modelling: CATIA, Creo, SolidWorks, NX CAD, and Inventor
• Draughting: AutoCAD

What are the minimum computer hardware requirements for running CAD software?

1. CPU: Multi-core processor (Intel or AMD) with a minimum speed of $2\,GHz$, i5
2. RAM: $8\text{--}16\,GB$
3. GPU: $2\,GB$
4. Hard disk: memory capacity of $40\,GB$
5. Solid State Drive (SSD) for operating system
6. Monitor: IPS with $1920 \times 1080$ or higher resolution

How does standard ISO 216 classify paper formats into ranges?

ISO 216 classifies paper into A-Series, B-Series, and C-Series, where the A-Series is the primary range, and the B-Series and C-Series are subsidiary ranges.

What are the trimmed sheet dimensions for A0, A1, A2, A3, and A4 paper sizes under BS EN ISO 5457?

• A0: $841 \times 1189\,mm$
• A1: $594 \times 841\,mm$
• A2: $420 \times 594\,mm$
• A3: $297 \times 420\,mm$
• A4: $210 \times 297\,mm$

What drawing sheet layout orientations are allowed for sizes A0 to A3 compared to sizes A4 to A8?

For A0 to A3, only landscape orientation holds for layout. For A4 to A8, both landscape and portrait orientations hold.

What are the standard color and thickness specifications for technical drawing paper?

The color is white, and the thickness is measured in area-density as $125\,g/m^2$.

Which pencil hardness grades are designated for lettering and sketching versus technical drawing?

HB is designated for lettering and sketching, while H and 2H are designated for drawing.

What are the four mandatory components of a blank drawing sheet according to ISO 5457: 1999?

1. Borders enclosed by edges of trimmed sheet
2. Title block
3. Frame limiting the drawing space
4. Centring marks

What are the four optional components of a blank drawing sheet layout according to ISO 5457: 1999?

1. Grid reference system
2. Metric reference graduation
3. Folding marks
4. Orientation marks

Where are centring marks placed, and what are their dimensions and purpose?

Centring marks facilitate positioning when a drawing is reproduced. They are placed at the centre of each of the four sides of the trimmed sheet, starting at the grid reference border and ending $10\,mm$ beyond the drawing frame.

What rules govern the formatting and labeling of the grid reference system on a drawing sheet?

It consists of alphanumeric fields with a length of $50\,mm$, starting at the axis of symmetry of the trimmed sheet. It is labeled from top downwards with capital letters (excluding I and O) and from left to right with numerals on both sides.

Where must the title block be positioned, and what is its standard length for a paper-based compact form under BS EN ISO 7200?

Irrespective of layout, the title block is located at the bottom right-hand corner of the drawing space, with a standard length of $180\,mm$.

What are the dimensions of the conventional COE (KNUST) title block?

The title block has an overall length of $150\,mm$ and an overall height of $45\,mm$, with the institutional identification block having a width of $50\,mm$ and rows of $10\,mm$ height.

How is Scale Factor expressed in terms of length, area, and volume?

$$\text{Scale Factor} = \frac{\text{Length of Drawing}}{\text{Actual Length}} = \sqrt{\frac{\text{Area of Drawing}}{\text{Actual Area}}} = \sqrt[3]{\frac{\text{Volume of Drawing}}{\text{Actual Volume}}}$$

What standard unit of measurement is specified by BS standards for technical drawing?

The millimetre ($mm$).

What is the primary function of a graphical scale on a drawing sheet?

A graphical scale is drawn on the drawing sheet to take care of shrinkage of the engineer's scale when the drawing paper is cold.

What are the five types of graphical scales?

1. Plain Scales
2. Diagonal Scales
3. Vernier Scales
4. Comparative Scales
5. Scale of cords

What is the formula for calculating Representative Fraction (R.F.)?

$$\text{R.F.} = \frac{\text{Length of an object on the drawing}}{\text{Actual length of the object}}$$

What are the distinguishing measuring capabilities of a diagonal scale compared to a plain scale?

A diagonal scale enables measurements to be made up to the second decimal place and measures distances in a unit and its immediate two subdivisions (e.g., $dm$, $cm$, and $mm$, or $yd.$, $ft.$, and $in.$), making it more accurate than a plain scale.

What three characteristics are used to categorise lines according to BS EN ISO 128-20?

Lines are categorised based on: a. Width / Thickness of line b. Continuity aspect of the line c. Colour of line

What is the standard width ratio for extra wide, wide, and narrow lines, and what ratio is used in mechanical engineering drawing?

The widths of extra wide, wide, and narrow lines are in the ratio $4:2:1$. Mechanical engineering drawing involves two line thicknesses in a $2:1$ ratio.

What are the description, standard thickness, and applications of Line Type A according to BS EN ISO 128-20?

Line Type A is a Continuous (thick) line with a width of $0.7\,mm$. It is used for visible outlines, visible edges, and the end of screws.

What are the description, standard thickness, and applications of Line Type B according to BS EN ISO 128-20?

Line Type B is a Continuous (thin) line with a width of $0.3\,mm$. It is used for fictitious outlines and edges, dimension and leader lines, hatching, outlines of adjacent parts, and outlines of revolved sections.

What are the description, standard thickness, and applications of Line Type E according to BS EN ISO 128-20?

Line Type E is a Chain (thin) line with a width of $0.3\,mm$. It is used for centre lines and extreme positions of movable parts.

What is the structural difference and application difference between Line Type F and Line Type G?

• Line Type F: Chain line that is thick ($0.7\,mm$) at ends and changes of direction, and thin ($0.3\,mm$) elsewhere; used for cutting planes.
• Line Type G: Chain line that is thick ($0.7\,mm$) throughout; used for indicating surfaces which have to meet special requirements.

What are the dimensional rules for spacing and dash lengths in D-Type (hidden) lines?

The gap between dashes must be $s = 1\,mm\text{ minimum}$, and the dash length must be $q = 2s\text{ to }4s$.

What are the dimensional rules for spacing, short elements, and long dashes in E-Type (chain) lines?

The gap must be $s = 1\,mm\text{ minimum}$, the short element length must be $q = 2s\text{ to }3s$, and the long dash length must be $p = 3q\text{ to }10q$.

What is the proper technique and pencil angle for drawing horizontal lines using a T-square?

Align the vertical edge of the T-square to the edge of the board with fingers, use a caterpillar motion with the fingers to hold the blade firmly, and draw the line holding the pencil at approximately $60^\circ$ to the paper while rotating the pencil slowly.

What rule governs the drawing of hidden lines at intersections and corners?

Hidden lines must directly butt against outside lines (touching without a gap) and join precisely at corners rather than leaving empty gaps.