6.0

Table Of Contents
86 | Chapter 7 Constraining Sketches
Constraining Tips
Constraining Sketches
Constraining a sketch defines how a sketch can change shape or size. In addi-
tion to the inferences by the software, you often need additional dimensions
or constraints.
Constraints may be fixed or variable, but they always prevent unwanted
changes to a feature as you make modifications.
Tip Explanation
Determine sketch
dependencies
Analyze the design to determine how sketch elements
interrelate; then decide which geometric constraints are
needed.
Analyze automatically
applied constraints
Determine the degrees of freedom not resolved by automatic
constraints. Decide if any automatic constraints need to be
deleted in order to constrain elements as you require.
Use only needed
constraints
Replace constraints as needed to define shape. Because
constraints often solve more than one degree of freedom, use
fewer constraints than degrees of freedom.
Stabilize shape
before size
If you apply geometric constraints before dimensions, your
sketch shape is less likely to become distorted.
Dimension large
before small
To minimize distortion, define larger elements that have an
overall bearing on the sketch size. Dimensioning small elements
first may restrict overall size. Delete or undo a dimension if the
sketch shape is distorted.
Use both geometric
constraints and
dimensions
Some constraint combinations may distort unconstrained
portions of the sketch. If so, delete the last constraint and
consider using a dimension or a different constraint
combination.