Re-framing the question
Can parametric modeling be the answer to drawing re-work?
"In the past, we've done design work with 2D CAD, which was fine, but there are always changes along the way, especially after you present the first draft of the design. It usually meant a lot of redrawing," explains Kirk Kelsey, joint-owner of the family-run Kelsey Woodworks.
"After going through three or four different changes in the frame widths on kitchen cabinets, I said 'there's got to be a better way than this,'" recalls Kelsey. "I had to go through every single cabinet and change every part three or four times in our old 2D CAD before the customer finally gave the OK."
With the younger generation of Kelseys working in the woodshop, Kirk Kelsey spends most of his time in his home office overlooking the Oregon coast, creating new designs for commissioned furniture pieces, which he now models in 3D CAD. Solid modeling, in fact, has become the Rockaway Beach woodworker's newest fascination. The software allows him to easily reproduce the furniture concept he has in mind, and then, when the scale and size of item needs adjustment according to a client's wishes, he can change the entire design in a few mouse clicks. Solid modeling, Kelsey believes, is the solution to time-consuming re-work.
Solid modelers vary in their methods depending much on the material and end product of the design. For automotive exteriors, designers want advanced surfacing capabilities; sheet metal fabricators require specialized features indicating the types of seams and corners that are native to their medium. A 3D modeler for film and video animation demands advanced artistic effects. For custom woodworking, the most useful kind of solid modeler is parametric, as Kelsey has found through much trial and error.
Parametric solid modelers put not only parts in 3D, but also, as the name implies, keep track of their parameters, such as lengths, angles, and volumes; they also record the relationships between parts as they are configured. Instead of drawing just of lines (as is the case of 2D CAD), a designer can build a model with a three-dimensional geometric intelligence.
To take the simplest example, the six walls of a cabinet are linked since they form a box. Increasing the scale of one side necessitates the increase in area of all the other related panels. A parametric solid modeler recognizes the designer wants to expand the size of the box, and automatically re-dimensions of all the individual parts at the same time.
One Model, Multiple Pieces
Kirk Kelsey demonstrates the ease of 3D parametric from a simple bed frame, similar to the beds manufactured by his wife's employer, McRae & Sons. The craftsman-style design features four rectangular bedposts with a headboard and footboard composed of vertical slats. Kirk Kelsey modeled all the pieces for the bed, including the joinery, bolts, and caps, in a parametric solid modeler called Alibre Design.
The program offers some shortcuts. After Kelsey completes the model of the headboard assembly, and he copies it, types in new numbers for the height, and the copy becomes the footboard model. In a similar way, Kirk can type in new measurements for the overall bed assembly, so the twin bed becomes a full-sized bed. Alibre Design changes the bed rail lengths and adds in more vertical slats according to the logic of the original scheme.
"With a few more changes to the length and width, I could easily make it into a queen- or king-size bed," Kelsey explains.
If the typed-in length changes are not geometrically possible within the 3D assembly, Alibre Design alerts Kelsey to the conflict. By contrast, if the Kelsey made the same adjustments to a 2D CAD document, and forgets to correct a single length in one of the views, "we won't know it until after we cut through a nice piece of maple."
Kelsey has used the same re-sizing technique in his custom pieces. "Our most popular piece at Kelsey Woodworks is what we call the California Shaker table, as it is a basic Shaker table crossed with the 1960's California Roundover style of furniture where everything was rounded with a router," says Kelsey. The Kelsey Woodworks has produced many variations in this design series over the years. "I enjoy creating a handcrafted piece of furniture and then producing it in small batches, which makes it affordable to more people."
The hall table version of the California Shaker is 9 inches wide and 30 inches long. Without any re-drawing, Kelsey can change the "30" to a "9" and generate a model of a matching square pedestal table.
The Long Search for Wood-Friendly Software
The full advantages of 3D CAD have been slow to come to the woodworking world, even though the technology is in practice in many other fields of design. Brand name solid modelers in recent years had been geared for gears: they were bulky software packages meant for large mechanical engineering firms. Their features were powerful, Kelsey says, but the multitude of commands became too complicated to remember. These applications preferred crunch millimeters instead of thirty-seconds of an inch, and were overpriced for an individual woodworker.
Kelsey sampled several programs custom-made for wood products with 3D capabilities, but these, he says, lacked the same power. They were good for plywood-type construction like mass-produced case goods, and not much else. They did not offer the capabilities for the advanced curves and joinery of Kelsey's more sophisticated furniture designs. For many years, there were no practical forms of 3D CAD for wood; the solutions either cost too much or offered too little.
Alibre, Inc. made waves in the software industry in 2005 by releasing a completely free parametric solid modeler. Alibre Design Xpress, the free downloadable version, contained virtually all the same tools and functionality as high-end mechanical engineering packages. The free release made 3D technology accessible to everyone for small-sized projects, especially individual users who would not spend thousands on a professional engineering package. After Kelsey tested the Xpress version, and for a small online fee, upgraded to the full version of Alibre Design, allowing him to model any size of project.
"With a parametric modeler like Alibre Design, I can change dimensions rather quickly. I create the look of the design, then fiddle with the dimensions and scale afterward to fit the client's requirements," says Kelsey. "The application also has all the power of the more expensive modelers, so I can easily add more complex curvatures. It turned out to be a very good tool for woodworking design."
Shelf Life
In a larger example of matching pieces, Kelsey worked with Jim Howe Woodworking & Design on a project for an entire room of shelving. The project consisted of large wall cases and smaller bookcases all with the same design details. The size and depth of the cases and shelves vary with the alcoves and walls of the client's room.
"The wall unit was the initial model created, from which we would derive the other bookcases on the other walls of the library," explains Kelsey. "After the first case is designed, we take and resize the model to rapidly create all the other cases throughout the entire room. With AutoCAD, we would have to draft every different case. For small adjustments needed for the installation, we would again have to redraw all the different parts that each change affects. With the top-down construction method in Alibre Design, we simply make one change to the dimensions of the overall assembly, and all the parts change automatically."
The finished model looks like the final product, which helps when presenting the idea to clients before the piece is built. Models may be rendered with different colored patterns to indicate the difference between walnut and maple. The 3D perspective renderings of the furniture can even be exported to a JPEG graphics file, and even 'photoshopped' into a picture of the customer's room.
"It's hard to sell a design with just 2D drawings. Most buyers can't visualize what it looks like," says Kesley. "Solid modeling gives me a virtual prototype -- a glimpse of the final design before any wood is cut."
Alibre Design also exports exploded 3D views of the assemblies, especially useful in Kelsey's case, when others are doing the construction. "The exploded view is so valuable in the ability to communicate how it is assembled. Someone else can see that you have to put in a lag bolt, for example, and then you use a plug in order to hide the bolt."
Nested Development
Customers typically do not pay for drawings; they pay for the finished product. All the more reason, Kelsey argues, to create design plans as efficiently as possible. "If you're not getting paid for drawing, why waste extra hours drawing when you can avoid it?"
Kirk Kelsey's enthusiasm for the solid models has spread to the rest of the household. Kirk has been evangelizing the virtues of Alibre Design to his wife, Connie, who, besides her role in the family business, creates 2D designs in AutoCAD for McRae & Sons' wood manufacturing operation. Founded in 1958, McRae & Sons represent the last remaining domestic manufacturer of wooden paintbrush handles.
Kirk Kelsey tried out his new parametric solid modeling capabilities on one of Connie's frequent design tasks. Two McRae paintbrush handles can be nested diagonally in one rectangular block of wood. To determine the most efficient size of block, and produce all the required construction documents, takes Connie Kelsey up to four hours using AutoCAD.
Kirk tried the same problem in Alibre Design. He first sculpted the 3D handle, copied it for its nested twin, and then circumscribed a virtual box around it, which represented the block of wood. "It took me just an hour the first time. Now that I have it set up, I can complete a new handle design in a half an hour," says Kirk Kelsey.
Connie Kelsey was impressed. "Alibre Design ís an incredible program. Although I use AutoCAD at work, I don't consider myself a very technical person. I like the fact that Alibre Design is user friendly. It's more of a tool that an artist would use." Connie Kelsey is now evangelizing herself, trying to convince her employer to adopt parametric solid modeling throughout the workplace.
After much anticipation, wood finally has a friend in the world of 3D CAD. According to Kirk Kelsey, "Alibre's parametric modeler is a great program and very applicable to woodworking."
About Kelsey Woodworks
Kirk and Connie Kelsey create specialty woodworking designs for furniture, cabinetry and case goods. Kelsey Woodworks is based in Rockaway Beach, Oregon. For more information, please visit www.kelseywoodworks.com.
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