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BeginnerFree AutoCAD course about 14 min

Basic drawing: aids, selection and undo

Before learning individual shapes, learn the drawing aids that keep lines straight and exact, and the few commands you will use hundreds of times a day.

In this lesson you will

  • Use Ortho and Polar tracking to draw straight and angled lines
  • Use direct distance entry
  • Draw rectangles precisely
  • Erase, undo and redo with confidence

Drawing aids on the status bar

Ortho and Polar can't both be on: turning one on turns the other off. Many drafters use Polar at 45° increments all the time.

AidKeyUse it for
OrthoF8Forces lines horizontal or vertical
Polar trackingF10Snaps the cursor to set angles (e.g. every 45°) and shows a tracking line
Object snapF3Snaps to exact points on objects (next lesson group)
Object snap trackingF11Tracks from snap points to find new points
Grid / SnapF7 / F9A visual grid and cursor steps; rarely used in architecture

Direct distance entry

The fastest way to draw exact lengths: start a line, point the cursor in a direction (Ortho or Polar keeps it true), type the length and press Enter. With Ortho on, pointing right and typing 3600 draws exactly 3600 to the right. This is how most drafters draw walls.

Rectangles

A rectangle is a single closed polyline, so it offsets and fillets as one object.

  1. 1Type REC (RECTANG) and Enter.
  2. 2Pick the first corner or type 0,0.
  3. 3Type @4000,3000 for a 4000 × 3000 rectangle.
  4. 4Use the Dimensions option instead if you prefer to type length and width separately.

Erase, undo and redo

  • ERASE (E) — select objects and press Enter, or select first and press Delete.
  • UNDO (U or Ctrl+Z) — steps back one command at a time. UNDO with a number undoes several at once.
  • REDO (Ctrl+Y) — reverses an undo.
  • OOPS — brings back the last erased objects even after other commands.

Inside LINE and PLINE, typing U removes just the last segment without leaving the command.

Save often

Press Ctrl+S every few minutes. AutoCAD also auto-saves (Options › Open and Save), and keeps a .bak copy of the previous save — but neither replaces saving.

Quick reference

Command / toolHow to start itWhat it does
RECTANGRECDraws a rectangle as one polyline
ERASEE or DeleteDeletes selected objects
UNDO / REDOCtrl+Z / Ctrl+YSteps back and forward through commands
OrthoF8Horizontal and vertical only
Polar trackingF10Snaps to set angle increments

Common mistakes

  • Lines are almost, but not quite, horizontal.

    Turn on Ortho or Polar before drawing; fix existing ones with the Properties palette or ALIGN.

  • Pressing Delete during a command does nothing.

    Finish or cancel the command first, then select and delete.

Exercise

A simple building outline

  1. Turn on Ortho (F8).
  2. Start LINE, click a start point, then point right and type 8000, up 6000, left 8000, and C to close.
  3. Draw a 1200 × 2400 rectangle inside it with REC.
  4. Erase the rectangle, then bring it back with OOPS.
  5. Undo three times and redo once.

You should end up with: An exact 8000 × 6000 outline drawn with direct distance entry.

Checklist

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Lesson quiz

1 / 4

Which key toggles Ortho?

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Free, independent learning material written for KitWren. AutoCAD and AutoCAD LT are registered trademarks of Autodesk, Inc. KitWren is not affiliated with, sponsored or endorsed by Autodesk. We never provide software downloads, licence keys or cracks — use the official sources.