1. Geometric Constraints
When making solid models, constraints are necessary to produce parts of exact shapes and sizes. To make a part parametric it is necessary to use as many geometric constraints as possible. The next set of slides will show what that geometry is.

2. Geometric Constraints
Parallel - Lines that are equal distance from
each other at each point along their length.
These two lines are parallel. The lines are
also representing the symbol for parallel.
Perpendicular - Lines that are 90° from one another.
These two lines are perpendicular and
represent the symbol for perpendicular.

3. Geometric Constraints
Horizontal - A line is horizontal when it is parallel to
the horizon. In solid modeling, the line is also parallel
in the horizontal projection plane and will appear true
length.
Vertical - A line is vertical when it is perpendicular to
the horizon. This line will be parallel to the front and
profile projection planes.

4. Geometric Constraints
Tangent - A line or arc that has one point in common
with an arc. If a line is tangent with a circle(Figure A),
the line will be perpendicular with a line drawn from the
point of tangency through the center point of the arc.
If two arcs are tangent (Figure B), a line drawn between
the centers will intersect at the point of tangency.
Figure A
Figure B

5. Geometric Constraints
Concentric - Circles or arcs that share the same center
point.
These circles and the arcs share the same
center point.
Coincident - Points that share the same location
on the coordinate plane. Points may also be parts
of arcs or curves.

6. Geometric Constraints
Collinear - Lines that if projected at each other will
become the same line.
Collinear lines
Coplanar - Two or more objects that sit in the same
plane.
Fixed Point - A point that has been forced to stay in
one location in space.
Equal - Two or more lines, arcs, or circles that are given
the same magnitude.
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