Engineering Drawing Study Notes

A comprehensive set of vocabulary flashcards covering engineering drawing instruments, pencil grades, sheet sizes, dimensioning methods, projection types, conic sections, and solid geometry definitions.

Engineering Drawing

The way of representation of objects OR ideas on a plane paper with the help of some good instruments by systematic means of line to represent an object in its proper shape, size and dimension.

T-Square

An instrument consisting of 2 parts, blade & base, used to draw parallel and perpendicular lines with proper measurement.

$30^\circ - 60^\circ$ set square

An instrument used to draw lines at $30^\circ$, $60^\circ$, and $90^\circ$.

$45^\circ - 45^\circ$ set square

An instrument used to draw lines at $45^\circ$ and $90^\circ$.

Long/Large compass

An engineering instrument used to take a radius greater than $20\,\text{mm}$.

Small / wheel compass

An engineering instrument used to take a radius less than $50\,\text{mm}$.

Divider

An instrument preferably used to divide line, arc and circle into equal and proportional parts.

H Pencil Grade

Stands for Hardness; as the number increases, the ratio of clay increases so hardness increases and the pencil becomes light.

B Pencil Grade

Stands for Blackness; as the number increases, the ratio of graphite increases so softness increases and the pencil becomes dark.

IS 962:1989

The standard stating that the ratio of thick to the thin line shall not be less than $2:1$.

French Curve

An instrument used to join a series of points to form a smooth curve.

Mini Drafter

A combination of T-square, set square & protractor that works with some limitations.

A0 Drawing Sheet Size

$1189 \times 841\,\text{mm}$.

A1 Drawing Sheet Size

$841 \times 594\,\text{mm}$.

A4 Drawing Sheet Size

$297 \times 210\,\text{mm}$.

Continuous or chain dimensioning

A dimensioning arrangement used only where the possible accumulation of tolerance does not endanger functional requirements.

Progressive or parallel dimensioning

An arrangement where all dimensions are given from a common baseline, with smaller dimensions placed nearer the view.

Superimposed Running Dimensioning

A simplified parallel dimensioning method used where there is space limitation.

Combined dimensioning

A method of placing single dimensions by combining chain dimensioning and dimensioning from a common feature.

Perspective view

A view in which the observer is at a finite distance, mimicking what the human eyes see.

Orthographic projection

A parallel projection in which projectors are parallel to each other and perpendicular to the plane of projection.

1st angle projection

A method where the object is in the first quadrant (between observer and POP), the plane is non-transparent, and the Front view is above the XY line.

3rd angle projection

A method where the object is in the third quadrant, the plane of projection is between the observer and object, and the Front view is below the XY line.

Trimetric projection

An axonometric projection where all three axes of space appear unequally foreshortened and none of the angles is equal.

Dimetric projection

An axonometric projection where two of the three axes of space appear equally shortened and two angles are equal.

Isometric projection

An axonometric projection where all three axes of space appear equally foreshortened and all three angles are equal.

Ellipse (Cutting Plane)

A conic section formed when the section plane cuts all the generators and $\beta < \alpha$.

Parabola (Cutting Plane)

A conic section formed when the section plane is parallel to the generator and $\beta = \alpha$.

Hyperbola (Cutting Plane)

A conic section formed when the section plane cuts the double cone and $\beta > \alpha$.

Ellipse (Locus)

The locus of a point moving such that the ratio of its distance from a focus to a directrix is constant and less than $1$ ($PF/PM < 1$).

Parabola (Locus)

The locus of a point moving such that its distance from a fixed point (focus) and a fixed straight line (directrix) are always equal ($PF/PM = 1$).

Hyperbola (Locus)

The locus of a point moving such that the ratio of its distance from a focus to a directrix is constant and greater than one ($PF/PM > 1$).

Tetrahedron

A regular polyhedral with $4$ equal equilateral triangular faces.

Cube/Hexahedron

A regular polyhedral with $6$ equal square faces.

Dodecahedron

A regular polyhedral with $12$ equal regular pentagonal faces.

Icosahedron

A regular polyhedral with $20$ equal equilateral triangular faces.

Frustum

The remaining portion of a pyramid or cone after it is cut parallel to its base and the top part is removed.

Truncated

The remaining portion of a solid after it is cut inclined to its base and the top part is removed.