FreeCAD is a computer-aided design system for building measured objects as editable models. A FreeCAD document can hold sketches, solid bodies, assemblies, drawing pages and manufacturing data. The important distinction from a simple mesh editor is the parametric history: dimensions and relationships remain attached to model objects, and a changed value can recompute the later operations that depend on it.
Workbenches divide the job
FreeCAD groups commands into workbenches rather than displaying every command at once. Sketcher creates constrained two-dimensional geometry. Part Design turns sketches into a history-based solid. TechDraw places model views and dimensions on drawing pages. Other workbenches address assemblies, BIM objects, machining paths and finite-element analysis.
Changing workbenches does not create a separate project. The same document can pass between them, but each workbench uses its own objects and assumptions. A command described in a tutorial may remain hidden until the matching workbench is active, which can make the interface appear incomplete to a new user.
Constraints drive sketches
A sketch begins as lines, arcs and circles. Geometric constraints make lines horizontal, points coincident or curves tangent. Dimensional constraints assign lengths, radii and angles. The solver reports whether the sketch remains under-constrained or has conflicting rules.
A shape that looks correct can still move because its position or size is not fully constrained. Adding dimensions without reading the solver can produce redundant constraints and stop the sketch from solving. FreeCAD therefore treats a sketch as a system of relationships, not merely a drawing traced with the mouse.
Bodies keep an order
Part Design stores additive and subtractive steps inside a Body. A Pad can turn a closed sketch into a solid, and a Pocket can remove material from that result. Later fillets, holes or patterns refer to the geometry created earlier in the history.
Only one Body is active at a time even when the document contains several. Creating a sketch while the wrong Body is active places the new object in an unexpected branch. Moving or deleting an early operation can also invalidate later references, so the model tree deserves the same attention as the three-dimensional view.
References can break
Attaching a sketch directly to a generated face or edge is convenient, but a large upstream edit can rename or replace that geometry. A later sketch may then attach to the wrong face or lose its support. FreeCAD’s documentation recommends standard planes, axes, datum geometry or a master sketch when the model must tolerate substantial dimension changes.
This constraint affects how a durable model is planned. A quick prototype may survive face-based attachments, while a design expected to change repeatedly benefits from stable construction references. Repair usually means identifying the first broken dependency rather than editing every red item in the tree.
Exchange loses history
FreeCAD reads and writes geometry through formats that include STEP, IGES, STL, OBJ, DXF, SVG and IFC. These formats do not carry the same kind of information. STEP can transfer exact solid geometry, while STL stores a triangulated surface intended for mesh-based workflows. A file that opens successfully may therefore lack editable sketches and the original operation history.
The native FCStd document retains FreeCAD objects and their relationships. Exporting a manufacturing copy should not replace that source document. Import quality also depends on the format and the workbench handling it, so a model should be checked for missing faces, altered units and disconnected solids before downstream work begins.
Outputs need preparation
A three-dimensional model is not automatically a finished drawing or printable object. TechDraw needs views, scale and dimensions on a page. A print export needs a suitable mesh and valid solid geometry. A machining job needs stock, tools and paths that match the actual machine setup.
FreeCAD keeps these outputs linked to the model where the chosen workflow supports it, but recomputation can expose errors after a design change. The report view and model tree identify the failed operation. Fixing the earliest failed dependency normally restores more of the document than suppressing errors at the end.
