3.1 Tools and commands for constructing 2D drawings.

Tools and commands for constructing 2D drawings are the functions in drafting software used to create, modify, measure and annotate flat drawings such as plans, elevations and details. Draw commands create new objects like lines, circles and arcs; modify commands change existing objects by moving, copying, trimming or offsetting them; and inquiry and annotation tools measure objects and add text. Each command can be started from the ribbon or toolbar, by typing its name or shortcut at the command line, or from a right-click menu, and most commands then prompt the user for points, distances or options. Mastering these commands lets a designer produce accurate drawings quickly and change them easily when the client requests revisions. Example: a designer drawing a pharmacy's dispensing counter uses the Rectangle command for the counter top, Offset for the edge band, Fillet to round the front corners and Array to place eight evenly spaced drawer fronts, completing the plan in minutes.

3.1.1 Methods of entering commands and points

Commands and points can be entered in several ways, and skilled users combine them for speed and accuracy. Accurate point entry is essential because a drawing built from guessed points cannot be dimensioned reliably. Example: a draughtsperson at a microfinance bank's estates office types exact coordinates for the banking hall counter instead of clicking by eye.

Ways of entering commands

• Ribbon and toolbars: Clicking a command icon on the ribbon or toolbar, suitable for learners still memorising commands.
• Command line: Typing the command name or its shortcut, such as L for Line or CO for Copy, then pressing Enter, which is the fastest method for experienced users.
• Right-click menus: Selecting recent commands or options from the shortcut menu at the cursor.
• Repeating commands: Pressing Enter or the spacebar after a command finishes repeats the last command.
• Dynamic input: Typing values in boxes that appear next to the cursor instead of at the command line.

Ways of entering points

Worked example: finding a point with relative polar coordinates

X distance = length × cos(angle)

Y distance = length × sin(angle)

A line is drawn from a point using @1000<30. Use cos 30° = 0.866 and sin 30° = 0.5.

X distance = 1000 × 0.866 = 866 mm

Y distance = 1000 × 0.5 = 500 mm

The line ends 866 mm to the right and 500 mm above its start point.

3.1.2 Draw commands

Draw commands create new geometry, and almost every 2D drawing is built from a small set of them. Choosing the right command keeps drawings clean; for example, a polyline outline of a table top is one object that can be offset in a single step. Example: a school's furniture designer draws classroom desks with Rectangle, the chairs' rounded backs with Arc, and the waste bins with Circle.

Steps for drawing a rectangular table top with a rounded edge

1. Start the Rectangle command: Type REC and press Enter.
2. Choose the fillet option: Type F and enter a radius of 50 mm for rounded corners.
3. Pick the first corner: Click a point or type coordinates such as 0,0.
4. Enter the size: Type @1800,900 to create a table 1800 mm long and 900 mm wide.
5. Offset the edge: Use Offset with a distance of 20 mm inward to show the edge band.
6. Add the chairs: Draw one chair with Rectangle and Arc, then copy it to the other positions.
7. Check the size: Use the Distance or List command to confirm the table measures 1800 mm by 900 mm.

3.1.3 Modify commands

Modify commands change existing objects and make up much of the drafting work, since designs are refined many times. Most modify commands ask the user to select objects, then a base point or distance, and many offer extra options such as making copies. Example: a hotel's renovation designer draws one guest room bathroom layout, then uses Mirror and Copy to repeat it for the twenty rooms on the floor.

Selecting objects for modification

• Pick selection: Clicking objects one at a time to select them.
• Window selection: Dragging from left to right selects only objects fully inside the box.
• Crossing selection: Dragging from right to left selects objects inside or touching the box.
• Fence selection: Drawing a line that selects every object it crosses, useful for trimming many lines.
• Removing from a selection: Holding Shift and clicking an object removes it from the selection set.
• Quick select: Selecting all objects with a shared property, such as every object on one layer.

Steps for arranging conference chairs with a polar array

1. Draw the table: Draw a round table with the Circle command at the required diameter.
2. Draw one chair: Draw a single chair at the top of the table, facing the centre.
3. Start the Array command: Type ARRAYPOLAR and press Enter.
4. Select the chair: Pick the chair and press Enter.
5. Specify the centre: Snap to the centre of the table as the centre of the array.
6. Set the number of items: Enter the number of chairs, for example 8.
7. Set the angle to fill: Keep 360 degrees so chairs are spaced evenly all round.
8. Confirm the array: Press Enter and check that every chair faces the table.

Worked example: spacing of chairs in a polar array

Angle between chairs = 360 ÷ number of chairs

A round table in a microfinance boardroom is to seat 8 chairs.

Angle between chairs = 360 ÷ 8

Angle between chairs = 45°

3.1.4 Inquiry and annotation tools

Inquiry tools measure and report information about objects, while annotation tools add text and notes that explain the drawing. They are used to check that geometry is correct and to make drawings readable by contractors and clients. Example: a designer preparing a flooring quotation for a dental clinic uses the Area command to measure the waiting room before ordering vinyl.

Inquiry tools

• Distance (DI): Measures the length and angle between two points.
• Area (AREA): Measures the area and perimeter of a closed shape or set of points.
• List (LI): Shows the properties of selected objects, such as layer, length and coordinates.
• ID point (ID): Displays the coordinates of a chosen point.
• Measure geometry (MEA): Measures distance, radius, angle, area or volume in one tool.

Annotation tools

• Single-line text (DT): Adds short labels such as room names.
• Multiline text (T): Adds paragraphs of notes with formatting.
• Leaders (MLD): Adds an arrow and text pointing to a specific item.
• Tables (TB): Creates schedules such as finish or door schedules.
• Revision clouds (REVCLOUD): Highlights changed areas of a drawing.

Worked example: floor area for finish ordering

Area = length × width

A waiting room measures 6.2 m by 4.5 m, and 10% extra is added for cutting waste.

Area = 6.2 × 4.5 = 27.9 m²

Waste allowance = 10 ÷ 100 × 27.9 = 2.79 m²

Material to order = 27.9 + 2.79 = 30.69 m², rounded up to 31 m²