Vellum Solids' Unified Design Environment Provides a Better Tool for Product Design
By Robert Berger
Product Development Consultant
Bound Brook, New Jersey
As a designer of medical equipment, I am often asked to come up with product designs of hand held instruments. These types of products often require free-form handle shapes that can only be created with complex surfaces, and it is important to me that I have a CAD program that allows me to create these shapes. There is nothing worse than to come up with a great design, and then have to compromise it because your CAD program can not model it. I also want a CAD program that allows me to work naturally and does not hinder my design thinking or productivity.
I have tried many CAD programs including most of the mid-range solid modelers. The one that suits my needs best is Vellum Solids from Ashlar Inc., Austin, Texas. This program differs from other mid-range modelers in that it includes a strong surface modeling capability. Most of others do not offer surface modeling, or are just starting to include some rudimentary surfacing functionality. Vellum Solids also has a transparent user interface, allowing me to accomplish most operations with fewer steps compared to other mid-range programs. Perhaps most important to me, however, is Vellum Solids working environment, which I refer to as a unified design environment. The program never makes you transfer from one mode to another, such as from sketch mode, to part mode, to assembly mode, to drafting mode. All the tools I need to go from art to part are accessible from the same place, and this seems very well suited to how I work.
When I begin a design, the first thing I like to do is to create a detailed 2D layout. I think most designers are similar in this regard. It is not intuitive to go right into a solid modeler and start modeling parts, although this is the way most solid modelers force you to work. They assume you are going to start with sketcher to make profiles, from which you make solid objects. Before I get to that point, I want to have a good idea of the overall layout, how all the components fit together with everything drawn to scale. It's like drawing a map before you get in the car and go. 2D CAD programs are good for doing this quickly, and many people who use high-end solid modeling systems often keep an inexpensive 2D CAD program around for this reason. I did the same thing before I had Vellum Solids.
Once I have a good idea of how everything is going to fit together, then I'm ready to begin modeling the individual components as solids. Most of my clients want the design to be done in solids so they can use the data for programming manufacturing and rapid prototyping. As I mentioned, many of the products I design incorporate complex surfaces, so it helps me to have surface modeling capability. Some of the shapes I want to create can not be modeled with today's mid-range solid modelers.
At the point in the design when I have modeled the product as a solid, I have already used several tools--2D sketching, surface modeling, and solid modeling, yet the design is still in progress. In addition, I may also need to put parts together into an assembly or to create production drawings. Surface modeling is the Vellum Solids feature I really appreciate; most mid-range CAD programs aren't robust in this area. I also think other programs, fall short by requiring the user to switch from one mode to another to access the different functions. For example, to model a part you work you create a sketch in "sketch" mode and perform 3D operations in "part" mode. To put parts together into an assembly, you must switch to "assembly" mode. To create drawings, you switch modes again to the "drafting" mode. You are constantly looking at your design from a narrow window, which takes time and diverts attention from designing. I liken it to listening to the stereo rather than the music. You are paying so much attention to the tool that you lose sight of the creative aspect.
I like the fact that Vellum Solids does not require this type of switching between modes. All the geometry creation tools are always accessible on one of three palettes: the basic drawing palette, the surface modeling palette, and the solid modeling palette. For me, when I am trying to design something, the fewer steps it takes the better. The Vellum Solids environment has eliminated extraneous steps. It has fewer pull-down menus than other programs, and you are never more than two layers into a menu before you have the command you need.
To design a product in Vellum Solids, I start by opening a new file. On the screen, I create a 2D layout of the design using the tools on the basic drawing tablet. Creating the layout goes very quickly for several reasons. Vellum Solids' user interface is very intuitive. When you touch an icon, the cursor becomes context sensitive. Selecting the icon that creates a circle, for example, changes the cursor from an arrow to a circle. Once you have selected a command, a message line at the top of screen walks you through how to implement the command. For a circle, it will say something like "pick the center of the circle." In addition to this kind of assistance, Vellum Solids also includes a patented feature called Drafting Assistant that completely frees the designer from the complex commands that impair creativity in other CAD packages. The Drafting Assistant automatically identifies relationships like endpoints, midpoints, center points, perpendiculars, tangencies, and real and extended intersections. The program is always giving feedback. It does the work of maintaining alignments and ensuring that geometry is precise, freeing the user to concentrate on the design.
As I create the 2D layout, I organize the components in relation to each other by means of the software's layering capability. I place one component per layer. Vellum Solids gives me the option of turning layers on or off, so it's easy to see as much or as little of the overall assembly as I need. You can also show or hide objects that are on the same layer. As I model the components in solids, I keep them on their separate layers. This is a somewhat unusual approach to solid modeling. Most solid modelers don't offer a layering capability, but in my opinion, this is a better approach than using a separate assembly mode. It is an approach that most 2D CAD users are already use to. There's nothing new to learn. Working with layers makes it easy to place components in the proper relationships to each other. As I am creating a solid model of a component, I turn on the layers of the components around it. The Drafting Assistant makes it simple to place the new component in the proper position in relation to the components since it is always giving me feedback about where things are in space. Inherent in Vellum Solids' design environment is the ability to organize things in space easily, and it is very effective for putting together assemblies.
I recently used this approach to create a laboratory pipette for a medical device company. A pipette is an instrument with a suction mechanism that is used to transfer precise amounts of liquids. A pipette would be used to take a reagent from a bottle and place it into test tubes, for example. Ergonomic considerations were important in this project because a pipette is a hand-operated device that people in labs use all day long. It had to be small, so the components inside were tightly packed, and it had to fit comfortably into the hand, so complex surfaces were required.
Using Vellum Solids, I quickly created a 2D layout that let me look at the mechanism design and how everything might fit together and what the minimal clearances were. Once I had established that, I created the housing around the internals using the software's surface modeling palette. There was a lot of complex, freeform geometry, but nothing that Vellum Solids couldn't handle. If I had used another mid-range modeler, I know I would not have been able to create the design that I did. I would have compromised some shapes because a solid modeler alone would not have been able to create them. Using Vellum Solids, I was able to create high-end application geometry with a mid range modeler.
The next step was modeling everything in solids. For the housing, I stitched the freeform surfaces together to create a solid part. The data was transferred into the CNC programming system, Mastercam, to serve as the basis for making prototypes. Some of the parts are now being machined, others are being produced with stereolithography as patterns for subsequent RTV casting. On this project, the use of Vellum Solids enabled me to produce a more ergonomic product than I could have using another mid-range CAD program. It probably saved time as well because I wasn't jumping from mode to mode. With the unified design environment, I had all the tools I needed always at hand, and that was a big time-saver.
These days, most CAD programs are an assortment of off-the-shelf components. Vendors buy a modeling kernel such as ACIS or Parasolid, a visualization engine, IGES and STEP data transfer capabilities, and so on. The only difference between the many mid-range modelers out there is determined by the user interface. In my opinion, Vellum Solids stands out from the rest because of how well its user interface works. It is the easiest program to learn, the easiest to use, and the most productive, even for inexperienced 3D modeling CAD users.
For more information contact Ashlar Incorporated, 12731 Research Blvd Bldg A, Austin, TX 78759. Phone: 512-250-2186 or 800-877-2745. Fax: 512-250-5811 E-mail: info@ashlar.com Internet: www.ashlar-vellum.com