Solidworks, not Surfaceworks
One of the advantages of Goddard Inc. is the close relationship of the Industrial Design and Engineering departments. This communication enables us to provide our clients and manufacturing vendors with stable and familiar CAD files, suitable for the ramp-up to production. To do this, the ID group works in parallel with engineering to arrive at a solution that is both aesthetically appropriate, but also meets the functional requirements of the project. As is often the case, the industrial designers are tasked with wrapping a precision mechanism from the engineering team with a killer aesthetic while maintaining proper ergonomic control surfaces and manufacturability.
The designer must proceed deliberately and with forethought as an overly complex CAD file will bog down computers, cause delays due to tracking down errors and ultimately eat up precious hours of the project. The final manufacturing method of the product needs to be considered as well, will tangent surfaces suffice, or will the model need highly accurate continuous curvature? The design must be vetted out through sketching and model making; the designer should not be designing from within the CAD program. Some NURBS programs are better than others for 3-D experimentation, but as a whole, the tools are inhibitive to the design process and should be limited to execution rather than development. Solidworks provides a very comprehensive set of tools for designers and engineers alike, from concept through to production, but depending on use, it too, can be a limiting factor in the design process.
With experience, a designer will become aware of the limitations or quirks of the software. While Solidworks is a powerful tool in many respects, I have found instances where overly complex surface models tend to cause instability. Identifying and finding stable solutions is par for the course with any set of software tools, and is not indicative of weakness in Solidworks, but is yet another reason to plan ahead when starting a new CAD model.
The surfacing tools within Solidworks are integral to the creation of smooth organic forms. They enable the addition or removal of material in a specific area, precise control of curvature and the creation of forms simply not possible with the standard set of solid tools. Surfaces have many other advantages as a tool to be used in the creation of a solid model, but the designer needs to show discretion when choosing to use a surface or a solid for a given feature. While providing elegant swept forms, surfaces tend to add a fair amount of complexity to the model file and ending up with a cad file that only the designer knows how to manipulate is not helpful to anyone.
Solidworks seems to prefer to be used as a solid modelling tool first and foremost. In the past I have treated Solidworks like Alias or Rhino and created a large portion, if not all of a model in surfaces, with a final knit at the end to solidify the object. Once knit I was ready to start adding rounds to the final object, only to find that the knit lines were not suitable and were segmented during the knit and gap control steps. The gaps were a creation of the trim operation, but with 2 surfaces intersecting near perpendicular, there simply should not have been a gap present. In addition, during the creation of the model, there were several instances of lines with a tangent relationship that were not actually tangent after the trim operation. I would wrestle with the model for a day or so, only to rebuild the shape as a solid and find no errors and easily rounded edges in the same areas.
Through trial and error, I have found the best method for successful creation of complex organic geometry using Solidworks is a hybrid approach. The model should start or be turned into a solid body as early in the process as possible. The surfaces used to cut away sections or to control specific curvature should be used on a per-feature basis and not make up the entirety of the model. This has been shown to minimize complexity, reduce time consuming glitches and makes the model more accessible to others needing to work with the file. So keep the title in mind when setting out to create a new model, Solidworks, not Surfaceworks.
- Justin McCarthy, Senior Industrial Designer, Goddard Inc.