How to Add Dimensions in FreeCAD TechDraw

Adding dimensions to a 2D drawing view in FreeCAD’s TechDraw workbench is essential for creating precise, production-ready technical documentation. This guide walks you through the step-by-step process of placing linear, radial, and angular dimensions directly onto your views, positioning them neatly, and customizing their appearance and tolerances using FreeCAD's built-in dimensioning tools.

Prerequisites

Ensure you have your 3D model open and have already created a TechDraw page with at least one projection view inserted. Switch to the TechDraw Workbench via the workbench dropdown menu.

Adding Linear Dimensions (Length, Horizontal, Vertical)

  1. Select the Geometry: In your drawing view, hold the Ctrl key and select the elements you want to dimension. You can select:
    • A single straight edge.
    • Two vertices (points).
    • A vertex and an edge.
  2. Choose the Dimension Tool: Click one of the linear dimension icons on the TechDraw toolbar:
    • Insert Length Dimension: Automatically dimensions the true aligned length between the selected points or along an edge.
    • Insert Horizontal Dimension: Constrains the measurement strictly along the horizontal axis of the page view.
    • Insert Vertical Dimension: Constrains the measurement strictly along the vertical axis of the page view.
  3. Position the Dimension: Once placed, click and drag the dimension text to move it to your desired position on the sheet.

Adding Radial and Diameter Dimensions

  1. Select a circular or curved edge in your drawing view.
  2. Choose the appropriate tool from the toolbar:
    • Insert Radius Dimension: Adds a radius callout (prefixed with R).
    • Insert Diameter Dimension: Adds a diameter callout (prefixed with ⌀).
  3. Click and drag the dimension line to adjust the leader line angle and text placement.

Adding Angular Dimensions

  1. Select two straight edges that intersect or define an angle, or select three points (where the vertex of the angle is selected second).
  2. Click the Insert Angle Dimension icon on the toolbar.
  3. The dimension will appear displaying the angle in degrees; drag the arc and text to clear overlapping lines.

Editing and Customizing Dimensions

  • Move Text: Click and drag the text independently from the extension lines to improve readability.
  • Property View Adjustments: Select the dimension in the tree view or directly on the page, then switch to the Data or View tab in the bottom-left Property panel:
    • Format Spec / Prefix / Suffix: Add custom text, symbols, or change decimal precision.
    • Tolerances: Enable and set upper and lower tolerance limits under the dimension's Data properties.
    • Font and Styling: Adjust font size, arrow styles, and line weights in the View tab to match standard drafting requirements (such as ISO or ASME).