CAD Geometric Constraints 2 — Questions and Answers
Question 1: What is the key difference between geometric constraints and dimensional constraints in CAD?
- Geometric constraints define shape relationships; dimensional constraints define size and position numerically (Correct answer)
- Geometric constraints are applied first; dimensional constraints are applied last
- Geometric constraints only apply to 2D sketches; dimensional constraints apply to 3D models
- Geometric constraints are permanent; dimensional constraints can be changed
Correct answer: Geometric constraints define shape relationships; dimensional constraints define size and position numerically
Geometric constraints define qualitative relationships (parallel, perpendicular, tangent), while dimensional constraints assign numeric values for size and position.
Question 2: What does an 'Equal' constraint do when applied to two lines?
- Forces them to be parallel
- Makes them the same length (Correct answer)
- Aligns them end to end
- Makes them collinear
Correct answer: Makes them the same length
An Equal constraint forces two lines (or curves) to maintain identical lengths, so changing one automatically updates the other.
Question 3: Which constraint ensures a point lies exactly on a curve or line (not necessarily at its endpoint)?
- Coincident
- Pierce
- On Curve (Point On) (Correct answer)
- Fix
Correct answer: On Curve (Point On)
A 'Point On' or 'On Curve' constraint forces a point to lie anywhere along a line, arc, or spline rather than requiring it to match an endpoint.
Question 4: What is 'over-constraining' in CAD sketching?
- Applying more constraints than the sketch has elements
- Applying redundant or conflicting constraints that make the sketch mathematically unsolvable or over-defined (Correct answer)
- Adding too many dimensions to the model tree
- Using fix constraints on every element
Correct answer: Applying redundant or conflicting constraints that make the sketch mathematically unsolvable or over-defined
Over-constraining occurs when constraints conflict or are redundant, leaving no degree of freedom and making the sketch over-defined — most CAD tools highlight this as an error.
Question 5: Which geometric constraint makes two lines or curves meet at a 90-degree angle?
- Tangent
- Normal
- Perpendicular (Correct answer)
- Vertical
Correct answer: Perpendicular
A Perpendicular constraint forces two lines (or a line and a curve) to intersect at exactly 90 degrees.
Question 6: What does a 'Midpoint' constraint do in a CAD sketch?
- Splits a line into two equal halves
- Forces a point to lie at the exact center of a line or arc (Correct answer)
- Makes two lines equal in length
- Centers an element on the origin
Correct answer: Forces a point to lie at the exact center of a line or arc
A Midpoint constraint anchors a point (such as another line's endpoint) to the exact middle of a selected line or arc.
Question 7: In most CAD applications, what color are sketch elements typically displayed in when they are 'fully constrained'?
- Blue
- Black or dark gray (Correct answer)
- Red
- Green
Correct answer: Black or dark gray
Most CAD systems (SolidWorks, CATIA, Inventor) display fully constrained sketch geometry in black or dark gray, indicating no remaining degrees of freedom.
CAD Geometric Constraints 2
What is the key difference between geometric constraints and dimensional constraints in CAD?