We haven’t really considered annotational dimensions that will show up on a drawing, what its cosmetic look is, and whether a construction document be made from the drawing. All of the dimensions we’ve discussed so far have been “dynamic” dimension constraints, meaning that we’re mainly concerned with how our drawing functions, what its parametric relationships are, and how they work. You can access these new parameters from the Parameters menu. AutoCADExchange explains how using the Convert command in the Dimensional Tools ribbon allows you to change any line, arc, or circle into a dimensionally constrained one.

If you receive a drawing that has conventional dimensions, you can still convert them to parametric constraints. The geometry in the drawing is adjusted accordingly based on changes made in the manager. This gives you a visual of all the parameters and allows you to edit them not in the drawing itself, but in the Parameters Manager. AutoCADExchange explains another way to modify the values of geometric constraint, other than double-clicking on the value itself, using the Parameters Manager in the Parametric ribbon.

Inferred constraints work with you as you draw and apply themselves while making sure your drawing is set up properly. No longer will you be drawing first and implying constraints second. Now that we’re experts on dimensional constraints, AutoCADExchange is going to introduce us to the world of inferred constraints. Using dimensions can change the length of a line, change relationships between lines, and create new dimensional relationships. Lynn Allen takes dimensional constraints even further in the Dimensions tab and shows how using dimensions can make your drawing life a lot easier. Dimensional constraints and setting up formulas for them are discussed as well. As each constraint is applied, AutoCAD shows an icon in a constraint bar adjacent to the object that gets highlighted when you hover over it. He also explains the Autoconstrain tool to assign a number of constraints in one pass. AutoCAD expert David Cohn takes the constraint talk a little further using tangents, perpendicular lines, parallel lines, concentric circles and arcs, and horizontal constraints on the same objects. You also learn about the common parametric battle of “who changes whom.” Cadalyst and Autodesk blogger Lynn Allen explains the basics of parametric constraint tools and how to use geometric constraints such as parallel and perpendicular lines in AutoCAD.

Here are eight AutoCAD tips for parametric modeling. AutoCAD has supported 3D parametric constraints since AutoCAD 2010, but except for 3D power users, most AutoCAD drafters don’t take advantage of this dynamic modeling environment and the accuracy and information it can bring to your drawings.

Parametric 3d modeling with autocad