Explain dimensioning as it relates to 3-D modeling.

Question

What will be an ideal response?

Answer 1

If you have already been creating solid models, you probably noticed that drawings sometimes require more dimensions than what you would use when modeling. This happens because you can imbed certain geometric relations or constraints within a 3-D model that must be explicitly pointed out on a drawing.


Since these differences between the dimensions are required in 3-D models and the drawings are required for documenting the parts, drawings with dimensions for manufacturing are typically done at the end of the design process instead of at the beginning. As you model parts, you want to add geometric and dimensional constraints that capture the design intent for each part. Documentation drawings can then be completed with dimensions for manufacture when the design is complete.


One of the nice features of constraint-based modelers is the ability of the software to let you know when geometry has been underdimensioned or overdimensioned. Your goal should be to fully define the geometry with geometric and dimensional constraints. If a constraint or constraints are missing, the software usually has some type of indicator that the geometry is underdefined. When geometry is underdefined, you should be able to grab entities and move them. When too many dimensions or geometric constraints are present, the software lets you know that the geometry is overdefined or overconstrained. To correct this problem, you must delete a dimension or geometric constraint that is in conflict with other constraints.