# Sketcher reference

## Introduction

User *chrisb* wrote a lengthy 70-page reference manual for the Sketcher Workbench that covers many topics of using this workbench. For inexperienced users, it is a gentle introduction that covers the basic usage of the Sketcher, and then goes into many details of creating geometrical elements, and using each type of constraint.

The manual is a work in progress, as some sections are reviewed and updated depending on the development occurring on the Sketcher Workbench. The original manual was written for FreeCAD 0.17, then it was updated for 0.18, and now for 0.19. The latest manual can be found in the forum thread, Sketcher tutorial.

Due to the evolving nature of the manual, the document is also known as the "Sketcher lecture".

Example sketch in the reference manual.

## Contents

The general structure of the manual is:

- Basics
- Create a sketch
- The Sketcher window
- General remarks on degrees of freedom
- Auto constraints

- Geometric elements
- Common usage
- Line
- Circle
- Arc
- Polyline
- Rectangle
- Polygon
- Slot
- B-splines
- Conical sections
- Construction geometry
- Point

- Constraints
- Selecting constraints
- Applying constraints
- The solver
- Coincidence
- Point on object
- Vertical
- Horizontal
- Parallel
- Perpendicular
- Tangency
- Equality
- Symmetry
- Block
- Lock
- Horizontal distance
- Vertical distance
- Length
- Radius and diameter
- Angle
- Dos and don'ts with constraints
- External geometry

- Creating objects based on sketches
*(to be written)*- Sketches for pads
- Symmetry
- Placement and attachment offset
- Validate sketches

**General:**Create sketch, Edit sketch, Attach sketch, Reorient sketch, Validate sketch, Merge sketches, Mirror sketch, Leave sketch, View sketch, View section, Toggle grid, Toggle snap, Configure rendering order, Stop operation

**Sketcher geometries:**Point, Polyline, Line, Arc, Arc by 3 points, Arc of ellipse, Arc of hyperbola, Arc of parabola, Circle, Circle by 3 points, Ellipse, Ellipse by 3 points, Rectangle, Centered rectangle, Rounded rectangle, Triangle, Square, Pentagon, Hexagon, Heptagon, Octagon, Regular polygon, Slot, Arc slot, B-spline by control points, Periodic B-spline by control points, B-spline by knots, Periodic B-spline by knots, Toggle construction geometry

**Sketcher constraints:****Dimensional constraints:**Dimension, Horizontal distance, Vertical distance, Distance, Auto radius/diameter, Radius, Diameter, Angle, Lock**Geometric constraints:**Coincident (unified), Coincident, Point on object, Horizontal/vertical, Horizontal, Vertical, Parallel, Perpendicular, Tangent or collinear, Equal, Symmetric, Block**Other constraints:**Refraction (Snell's law)**Constraint tools:**Toggle driving/reference constraint, Activate/deactivate constraint

**Sketcher tools:**Fillet, Chamfer, Trim, Split, Extend, External geometry, Carbon copy, Select origin, Select horizontal axis, Select vertical axis, Array transform, Polar transform, Scale transform, Offset geometry, Symmetry, Remove axes alignment, Delete all geometry, Delete all constraints

**Sketcher B-spline tools:**Convert geometry to B-spline, Increase B-spline degree, Decrease B-spline degree, Increase knot multiplicity, Decrease knot multiplicity, Insert knot, Join curves

**Sketcher visual:**Select unconstrained DoF, Select associated constraints, Select associated geometry, Select redundant constraints, Select conflicting constraints, Show/hide circular helper for arcs, Show/hide B-spline degree, Show/hide B-spline control polygon, Show/hide B-spline curvature comb, Show/hide B-spline knot multiplicity, Show/hide B-spline control point weight, Show/hide internal geometry, Switch virtual space

**Additional:**Sketcher Dialog, Preferences, Sketcher scripting

**Getting started****Installation:**Download, Windows, Linux, Mac, Additional components, Docker, AppImage, Ubuntu Snap**Basics:**About FreeCAD, Interface, Mouse navigation, Selection methods, Object name, Preferences, Workbenches, Document structure, Properties, Help FreeCAD, Donate

**Help:**Tutorials, Video tutorials**Workbenches:**Std Base, Assembly, BIM, CAM, Draft, FEM, Inspection, Mesh, OpenSCAD, Part, PartDesign, Points, Reverse Engineering, Robot, Sketcher, Spreadsheet, Surface, TechDraw, Test Framework

**Hubs:**User hub, Power users hub, Developer hub