AutoCAD F8 Shortcut :Toggle ortho mode

If you want to control drawing direction in AutoCAD and draw only horizontal or vertical lines, the F8 shortcut (Ortho mode) is the fastest and most common way. This guide explains what the F8 / Ortho Mode does, how to use it step-by-step, alternatives, common problems and fixes, plus practical tips to work faster.

What is the F8 shortcut?

F8 in AutoCAD toggles Ortho Mode, which restricts cursor movement to horizontal or vertical directions relative to the current user Coordinate system (UCS). In short: when Ortho Mode is ON you can only draw at 0° or 90° (unless you change UCS).

Important terms:

• F8 — keyboard key that toggles Ortho (default).
• ORTHO — the AutoCAD command that toggles Ortho Mode.
• ORTHOMODE — the system variable (0 = off, 1 = on).
• status bar Ortho button — visual toggle in the drawing window.

Explanation: Why and when to use Ortho Mode

• Use Ortho Mode when you need perfectly horizontal or vertical lines (walls, grids, elevations).
• It prevents accidental diagonal segments, improving accuracy and speed for orthogonal drawings.
• Ortho is best for 2D drafting and basic plans; for angled construction use Polar tracking instead.

How to use F8 (step by step)

1. Start AutoCAD and open your drawing.
2. Press F8 on your keyboard to toggle Ortho Mode ON. You should see the Ortho indicator light up in the status bar.
   • Alternatively type ORTHO at the command line and press Enter; then type ON or OFF.
   • Or set the system variable: type ORTHOMODE then enter 1 (on) or 0 (off).
3. Start a drawing command (for example, type LINE and press Enter).
4. Move the cursor: movement will be constrained to horizontal or vertical directions only. Click to place endpoints.
5. To turn Ortho off, press F8 again, or enter ORTHO OFF.

Quick checks:

• Look at the status bar: the Ortho button shows the current state.
• If you prefer the command line, enter ORTHO.

Example scenario:

• Before: Drawing a wall by snapping freehand produces small angled segments.
• After: With F8 (Ortho ON), each segment snaps perfectly horizontal or vertical, eliminating diagonal mistakes.

Alternative methods (when you need angles other than 90°)

• Polar Tracking (F10) — Allows constrained drawing at specified increments (e.g., 30°, 45°). Use when you need non-90° angles.
• Object snap Tracking (F11) — Use alignment paths from object snaps to constrain points relative to geometry.
• Set Ortho by UCS — Rotate the UCS so your desired direction becomes horizontal/vertical, then use Ortho.
• Specify angle manually — Enter exact coordinates or polar coordinates when creating an entity (type @length<angle).
• Command-line: use ORTHO to toggle instead of keyboard (helpful if F8 is not mapped).

Common reasons F8 doesn’t work and fixes

1. Keyboard Function Lock (Fn) or Function Key Behavior

   • Problem: On laptops, F-keys may require the Fn key or a function lock to work.
   • Fix: Press Fn + F8 or enable Fn Lock in your laptop settings.

2. F8 remapped or disabled in AutoCAD (CUI customization)

   • Problem: Customizations or third-party utilities may have reassigned F8.
   • Fix: Open CUI (Customize user interface) and verify that F8 is assigned to the ORTHO command or reassign it.

3. ORTHOMODE system variable changed

   • Problem: ORTHOMODE is set to 0 by startup LISP or scripts.
   • Fix: Type ORTHOMODE at the command line and set value to 1 to enable.

4. Conflicting keyboard shortcuts or external utilities

   • Problem: Global hotkeys from other software intercept F8.
   • Fix: Close or reconfigure the other software; test in Safe Mode or a clean AutoCAD profile.

5. Status bar icon hidden

   • Problem: Ortho icon not visible, so state is unclear.
   • Fix: Right-click the status bar, ensure Ortho is displayed; use the ORTHO command to toggle.

6. Running command overrides Ortho behavior

   • Problem: Some commands or grips provide temporary constraints that appear to ignore Ortho.
   • Fix: Confirm Ortho state before starting the command; use Polar Tracking if you need angled constraints.

7. AutoCAD for Mac or different keyboard layout

   • Problem: Function keys differ on macOS or custom keyboards.
   • Fix: Use the ORTHO command, set ORTHOMODE, or remap keys in Mac preferences.

8. Hardware or keyboard malfunction

   • Problem: F8 physically not working.
   • Fix: Test with another keyboard, or use command line ORTHO.

9. Running a script or LISP that toggles Ortho

   • Problem: Startup script changes ORTHOMODE after launch.
   • Fix: Check startup scripts (acad.lsp, acaddoc.lsp) and remove or modify the toggle.

How to change or reassign the F8 key in CUI

1. Type CUI and press Enter.
2. In the Customize User Interface dialog, go to the Keyboard Shortcuts section.
3. Locate the F8 entry or the ORTHO command.
4. Reassign or restore the default F8 = ORTHO mapping.
5. Save and reload the CUI.

This restores the F8 behavior without changing system variables.

Tips to use Ortho Mode efficiently

• Use Ortho for grid-based or rectilinear layouts (floor plans, elevations).
• Combine Ortho with Object Snap (F3) to anchor to exact endpoints and intersections.
• Use Polar Tracking (F10) when you need consistent angled increments (e.g., 30°, 45°).
• Use UCS Rotation to make a different drawing axis align with Ortho constraints.
• If you need a temporary orthogonal constraint but do not want to toggle Ortho, use precise coordinate input (@distance<angle).

FAQ: How do I temporarily constrain to orthogonal while Ortho is off?

You can type exact coordinates or use Polar Tracking with the desired angle increment; there is no universal built-in temporary Ortho key on all versions — use ORTHO or set ORTHOMODE as needed.

FAQ: How do I set Ortho to always start ON when AutoCAD opens?

Set ORTHOMODE to 1 in your startup scripts (acad.lsp, acaddoc.lsp) or save a workspace/profile with Ortho ON. Alternatively, add the line (setvar “ORTHOMODE” 1) to your startup LISP.

FAQ: What is the difference between Ortho (F8) and Polar Tracking (F10)?

Ortho locks the cursor to horizontal and vertical only. Polar Tracking constrains the cursor to angles you define (e.g., every 30° or 45°). Use Ortho for strict 90° work, Polar Tracking for angled construction.

FAQ: F8 does nothing on my laptop — what should I try first?

Try pressing Fn + F8, toggle Fn Lock, or use the ORTHO command. If problems persist, test another keyboard or check for software intercepting F8.

FAQ: Can I change the angles Ortho uses?

Not directly — Ortho only enforces 90° increments. To work at other angles, rotate the UCS so your desired angle becomes horizontal/vertical or use Polar Tracking.

FAQ: Does Ortho work in 3D drawing?

Ortho constrains the cursor in the current UCS plane. In 3D modeling, Ortho can still limit movement in the UCS XY plane, but it does not lock along world Z or constrain arbitrary 3D directions. For 3D workflows, use Ortho carefully or choose other constraints.