Geometry & modeling
Degrees of freedom
Definition
Degrees of freedom are the independent ways a CAD component can translate or rotate. Assembly mates remove or control those motions; leaving unnecessary freedom makes position ambiguous and can add solver work.
Also known as: DOF, assembly degrees of freedom
Updated
Motion in an assembly#
A free rigid component can move along three axes and rotate around three axes. Mates remove, couple, or limit those motions so the assembly represents how the mechanism is meant to behave.
Onshape's Group help describes grouping as fastening selected instances together without changing their relative positions. That is useful for components that should behave as one rigid unit, but it is not a replacement for the joints required by a real mechanism.
Why unresolved freedom matters#
Unexpected degrees of freedom let components float or move in ways the designer did not intend. In a large assembly they can also increase the amount of mate solving required during motion or regeneration.
Onshape's 2026 assembly guidance says fully rigid subassemblies let higher-level assemblies skip mate-solving work for those subassemblies. Locking a mechanism for a layout task can also reduce work, but the lock must be removed when its real motion needs to be checked.
Sources
Related terms
Assembly
An assembly is a CAD model made of multiple parts or subassemblies positioned relative to each other with mates or joints. Assemblies are where fit, clearance, interference, and motion get checked.
Sketch constraint
A sketch constraint is a rule applied to 2D sketch geometry, such as coincident, parallel, tangent, equal, or a fixed dimension. When a sketch is fully constrained, nothing in it can move freely, which makes later edits predictable.