activity 5.2a
description
A CAD model can quickly display an engineer’s ideas in a realistic way. And those models can be used to generate technical drawings that can communicate the information necessary to make the idea a reality. In order to generate a 3D model, designs must start with sketches that are generated within the CAD program. These computer generated sketches will appear resemble hand drawn sketches in geometry (the combination of points, lines, and shapes), but have big advantages over hand drawn sketches. One important difference between a freehand sketch and a CAD sketch is accuracy. The lines of a CAD sketch can be drawn perfectly straight, with start and end points that occur in exact locations in space. By using numeric (dimensional) constraints a line may also be given precise length, placed a specific distance from another sketch feature, or constrained to be oriented at a specific angle from another straight line. By applying geometric constraints a line can be made perfectly horizontal or vertical. If more than one line is being sketched, they can be made perfectly parallel or perpendicular, collinear, or equal in length. Lines can be constrained to be tangent to circles or arcs, and two circles can be constrained to be concentric. In order to precisely model a part, the designer must be able to use dimensional and geometric constraints within the CAD program.
You have already used linear dimensioning in earlier activities. In this activity, you will learn about geometric constraints that are common to most CAD programs and practice applying these constraints to CAD sketches.
You have already used linear dimensioning in earlier activities. In this activity, you will learn about geometric constraints that are common to most CAD programs and practice applying these constraints to CAD sketches.
conclusion
What is a geometric constraint?
Relationships between geometric figures.
What are the different types of geometric constraints that are applied to sketches, and what are their functions?
Inscribed- drawn inside circle
Circumscribed-drawn outside shape
Tangent-shapes touching but not overlapping
Parallel-Lines will never touch
Perpendicular- Lines will intersect
Define “tangent”.
Tangent-shapes touching but not overlapping
Sketch a line tangent to two circles.
See photo below
Sketch three circles such that all circles are tangent to the other two.
See photo below
How is a geometric constraint different from a numeric constraint?
Numeric constraints control shape of figure, while geometric constraint is the relationship between geometric figures.
Relationships between geometric figures.
What are the different types of geometric constraints that are applied to sketches, and what are their functions?
Inscribed- drawn inside circle
Circumscribed-drawn outside shape
Tangent-shapes touching but not overlapping
Parallel-Lines will never touch
Perpendicular- Lines will intersect
Define “tangent”.
Tangent-shapes touching but not overlapping
Sketch a line tangent to two circles.
See photo below
Sketch three circles such that all circles are tangent to the other two.
See photo below
How is a geometric constraint different from a numeric constraint?
Numeric constraints control shape of figure, while geometric constraint is the relationship between geometric figures.
Questions from conclusion sketched out