Drawing at exact sizes (the whole point of CAD)

Last lesson you clicked out zigzags — lines from "somewhere" to "somewhere else". Fine for warming up, but remember why CAD exists: exactness. A builder can't build from "somewhere". This lesson is where doodling becomes drafting.

The idea: answer questions with NUMBERS

Recall the conversation pattern: AutoCAD asks "Specify next point:" — and last lesson you answered by clicking. But you can answer by typing instead, and typed answers are exact.

The workhorse method (90% of real drawing) is beautifully simple:

Point the mouse in a direction. Type a distance. Press Enter.

Draw a line exactly 5000 units long, rightward:

1. 1L, Enter
2. 2Click a start point anywhere
3. 3"Specify next point:" — move the mouse to the RIGHT (don't click!), type 5000, press Enter
4. 4A line exactly 5000 long appears. Esc or Enter to finish.

That's called direct distance entry: direction from the mouse, distance from the keyboard. Mouse says where, keyboard says how far.

Ortho: your straightness insurance

For that trick to give a perfectly horizontal line, the direction must be perfectly horizontal — and no human hand is. Meet your first drawing aid:

Ortho ON + direct distance entry = perfectly straight lines at exact lengths, effortlessly. This combination alone draws most of a floor plan.

Units: what does "5000" mean?

A crucial habit of mind: AutoCAD units are just numbers — you decide what they mean and stay consistent. The near-universal convention in metric building work: 1 unit = 1 millimetre. So a 5-metre wall is 5000 units, a door is 900, a desk is 1200×600. (US imperial drawings use feet-and-inches setups instead.) All this course's examples use millimetres.

Your first real shapes

A rectangle the size of a desk (1200 × 600):

1. 1REC, Enter
2. 2Click anywhere for the first corner
3. 3Type @1200,600 and Enter — done. An exact desk.

That @ notation means "measured from the last point": @1200,600 = "1200 along, 600 up from where I just clicked".

A circle with radius 300:

1. 1C, Enter
2. 2Click a centre point
3. 3Type 300, Enter. Exact circle.

Check your work — the tape measure: type DIST, Enter, then click two points: AutoCAD reports the exact distance between them. Measure your desk now — 1200.0000 exactly. Feel that? That's the click of drafting. "About right" has left the building.

The exercise that makes it stick

Draw this "room with a desk" (all in mm):

1. 1Rectangle 4000 × 3000 — a small room (REC, click, @4000,3000)
2. 2Inside it, your 1200 × 600 desk rectangle
3. 3A circle radius 250 near the desk — a stool
4. 4DIST-check all three; then draw a line along the room's top wall using Ortho + direct distance: exactly 4000

If all four measure exact — you are, as of today, technically drafting. Save the file (Ctrl+S) as room-practice.dwg; the next lessons build on it.