Lesson 2: Drawing Tools, Line Types, and Dimensioning Techniques

Learning Goal

Demonstrate the ability to create basic 2D technical drawings using appropriate drawing tools, line types, and dimensioning techniques.

Learning Objective(s)

1: Describe basic drawing tools to produce accurate 2D technical drawings.

2: Identify and describe different types of lines used in 2D drawings.

3: Apply standard dimensioning techniques to accurately annotate 2D drawings.

Instructional Content

Basic Drawing tools to produce accurate 2D technical drawings

To produce accurate 2D technical drawings, a variety of basic drawing tools are used, either manually or through computer-aided design (CAD). The following are the manual drawing tools:

Drawing Board: A flat surface used as a base for drawing. Ensures stability and precision during manual drafting. It is a flat, rigid surface used as the foundation for manual technical, architectural, or engineering drawings. It provides a smooth and stable surface to work on, helping ensure precision and accuracy when using tools like T-squares, compasses, and set squares.
T-square: Used to draw horizontal lines and align other drawing instruments. Slides along the edge of the drawing board for accuracy. It is a fundamental drafting instrument used in engineering, architectural, and technical drawing. It's primarily used to draw horizontal lines and serve as a base for using other tools like set squares, compasses, and scale rulers.
Set squares (triangles), also known as triangles, are essential drawing tools used in engineering, architectural, and technical drawing. They help draw accurate angles, particularly 90°, 45°, 30°, and 60°, and are used in combination with other tools like T-squares and drawing boards.
Compass: In engineering drawing, a compass is a precision drafting instrument used to draw circles, arcs, or to transfer measurements. It's a fundamental tool for technical drawing, especially when exact dimensions are critical.

Protractor: Used to measure and draw angles accurately. It is a tool used in geometry to measure and draw angles. It’s usually made of plastic or metal and is semi-circular or circular, marked with degrees from 0° to 180° or 0° to 360°.

Drawing Board:

A flat surface used as a base for drawing. Ensures stability and precision during manual drafting. It is a flat, rigid surface used as the foundation for manual technical, architectural, or engineering drawings. It provides a smooth and stable surface to work on, helping ensure precision and accuracy when using tools like T-squares, compasses, and set squares.

T-square:

Used to draw horizontal lines and align other drawing instruments. Slides along the edge of the drawing board for accuracy. It is a fundamental drafting instrument used in engineering, architectural, and technical drawing. It's primarily used to draw horizontal lines and serve as a base for using other tools like set squares, compasses, and scale rulers.

Set Squares (Triangles):

Set squares, also known as triangles, are essential drawing tools used in engineering, architectural, and technical drawing. They help draw accurate angles, particularly 90°, 45°, 30°, and 60°, and are used in combination with other tools like T-squares and drawing boards.

Compass:

In engineering drawing, a compass is a precision drafting instrument used to draw circles, arcs, or to transfer measurements. It's a fundamental tool for technical drawing, especially when exact dimensions are critical.
A compass (also called a divider when both legs have points) is a two-legged instrument, usually made of metal, with:
One pointed leg: Anchors at the center point of the circle or arc.
One leg with a pencil or pen: Draws the circle or arc.
Adjustable hinge/screw: Allows precise control over the radius.

used in geometry to measure and draw angles accurately. Typically semi-circular or circular, made of plastic or metal, marked from 0° to 180° or 0° to 360°, with a center point for alignment on the angle's vertex

Protractor: Used to measure and draw angles accurately. It is a tool used in geometry to measure and draw angles. It’s usually made of plastic or metal and is semi-circular or circular, marked with degrees from 0° to 180° or 0° to 360°.

How it works:

Place the center point (usually a small hole or mark at the bottom center) on the vertex of the angle.
Align one side of the angle with the baseline of the protractor (the straight edge).
Read the number on the curved edge where the second side of the angle points. That’s your angle in degrees.

Videos

Watch the video of Drawing tools below.

https://docs.google.com/document/d/1TYBc04X58H28fAeNG2M-QH_XbsoP-aG0Miz4fy8feA4/edit?tab=t.0

Different Types of Lines used in 2D Drawings

In engineering drawings, various line types are used to convey specific information clearly and accurately. The followings are key line types in engineering drawings

Visible (Object) Line: Represents the visible edges and outlines of an object. It is thick and continuous line.
Hidden Line: Represents edges and features not directly visible (behind or inside an object) and it is thin and dashed line.
Center Line: Indicates the center of holes, cylinders, and symmetrical objects. Thin line with alternating long and short dashes.
Construction Line: Used as a guide for drawing and layout, not part of the final drawing. It is very light, thin continuous line
Cutting Plane Line: Indicates where a section is cut to show internal features. Thick dashed line with arrows
Section Line (Hatching): Represents surfaces exposed by a cutting plane in sectional views. Thin diagonal lines within a cut area

Illustration of various line types used in 2D engineering and architectural drawings.

Diagram showing different types of lines used in 2D technical drawings, including visible lines, hidden lines, center lines, dimension lines, extension lines, section lines, and cutting plane lines—each with distinct patterns and purposes

Different Types of Lines used in 2D Drawings

Standard Dimensioning Techniques

Standard dimensioning techniques are essential for accurately annotating 2D technical drawings to ensure clear communication of size, shape, and features. It provides clear, accurate measurements to guide manufacturing, inspection, and assembly of parts. It Ensure clarity, accuracy, and uniformity in communicating sizes, positions, and tolerances of features in technical drawings. These techniques involve applying consistent measurement units, such as millimeters or inches, and using proper symbols like the diameter symbol (⌀) and radius (R) to specify circular features. Dimensions should be placed outside the object’s outline whenever possible, avoiding clutter and overlapping lines. Two common dimensioning methods are chain dimensioning, where measurements are placed sequentially from one feature to the next, and baseline dimensioning, where all measurements originate from a single reference point to improve accuracy. By adhering to these techniques, drawings maintain consistency, reduce manufacturing errors, and ensure universal interpretability.

Lesson 2 Activity

Complete the Drawing Tools, Line Types, and Dimensioning Techniques multiple choice questions activity below to check your understanding of the lesson.

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