Mechanical design concepts evolve from rough sketches at the preliminary design stages to full working drawings at the detail design stage. Traditional computer aided drafting systems allow designers to document and detail a design once it has been completed. These systems allow very little flexibility in the geometric modification of these drawings when design revisions are required. A large quantity of design information is stored in paper drawings and/or formats compatible with traditional CAD systems. Constraint based modelers, on the other hand, allow the designer to generate the shape (topology) of a component without defining the dimensions. In order to perform any modifications to the geometry the geometric entities (points, lines, etc.) must be constrained via dimensions. Parametric Modelers and Variational Geometry Systems, are examples of such technology. In these systems the components must be correctly dimensioned by the designer before the geometry can be manipulated. Dimensioning schemes are not unique and selecting a consistent dimensional scheme is a non-trivial, error prone task for any geometric component of reasonable complexity. Computational tools that bridge the gap between traditional CAD tools and constraint based systems will be extremely valuable to the designer, not only as a means to completely dimension an undimensioned component or partially dimensioned design but to access existing CAD data for manipulation and parametrization. The paper describes a constraint management approach to the automatic generation of consistent dimensioning schemes.