CAD and WOODWORKING

by Lee Alexander

TOOLS

Modern woodworking tools are marvels of engineering. It allows one person to accomplish in less time that which took a shop full of colonial furniture makers. Does that mean a guy or gal with a shop full of power tools automatically becomes a Hepplewhite, a Sheridan, a Tage Frid, or a Sam Maloof? Tools do not make artists and craftsmen. Owning a musical instrument does not make you a musician. Buying a better camera will not make you a better photographer. It is what you have inside yourself, your devotion to study, your willingness to change or even start over (which is why the kindling box for my woodstove is never empty); these are the elements that contribute to the satisfaction of “making something.” Good tools facilitate our efforts. I put CAD programs in this category.

What is CAD?

The acronym has two interpretations: Computer Augmented Design and Computer Assisted Drafting – I guess it depends upon how you view yourself for the task at hand. Compared to paper, T-square, and triangles I can attest that it can save a lot of trees. Eraser dust is no longer a companion to my “think sessions.”

A CAD program is no substitute for drafting basics. Elementary principles such as orthogonal and isometric views, dimensioning, line types (dashed for hidden, dot-dash for center lines, etc.) are all assumed. Knowledge of the basic concepts of geometry will go a long way in utilizing these programs.

CAD programs have a wide area of features and complexity. The industry standard is AutoCAD, an enterprise level application designed for teamwork and collaboration. At $3400, it is not likely to found on many home PCs. Even its low-cost companion package, AutoCAD LT (at $725), is overkill for most of us.

The middle ground is programs such as DesignCAD and TurboCAD from IMSI. I have had some experience with both of these applications (basic versions retail for about $100) and am presently using DesignCAD 3000. The illustrations for this article are screen shots from projects designed in that program.

My purpose is not to give a review of all the features of the program but to introduce its basic capabilities to the Novice SIG. There is a plentitude of lower cost (~$50) programs of the genre that focus on home subjects such as deck design, floor plans, interior decorating, etc. The two IMSI programs are quite broad in their features including 3D and solid model rendering; however, those topics will not be part of this introduction.

Being a woodworking tool freak, I had to have the new oscillating drum and belt sander by Rigid. It is a bench top model and that was the problem. Being a basement shop habitué, there is a severe shortage of benchtops. The answer was to make the tool's own table, shop style. My approach to projects follows a common path for amateurs: what is the need, what materials are available (in this case, my lumber stock), what tools are there to accomplish the job, and how much time do I want to devote to the project. This is not going to be a fine piece with a gleaming finish (actually, the table has no finish).

For the design phase, the tool and its use will set the dimensions. Of primary concern is the height of the work surface. The work pieces will be on the small side, so the height does not have to be low to clear the ceiling or reduce the work to lift heavy items. As compared to a table saw, power to feed a workpiece is minimal but will require control. Visibility is important – I will want to “sand to the line.” This led to standard height of work surface at just below the elbow – 39” in my case. This is close enough to see well without getting a face full of sawdust. The width and depth of the table top was determined by allowing some space to lay tools and jigs. The sander is not heavy so the table construction need not be “rugged.” The familiar tenoned aprons into mortised legs with lower stretchers should suffice. If using aprons, we might as well add a drawer.

Now let's see what CAD can do for us.

Note: The illustrations are screen shots from the CAD program. They are not intended to be actually used as any plans – just to give an impression of what the program can do. This accounts for the different line weights, they are equal in the application.

Each “view” is a layer, similar to the way many photo editing programs work. In fact, there are more than a few similarities between the two types of programs. In the CAD program, you can “group” lines to form entities. You can “clone” (duplicate) parts, create mirror images; arrange items in arrays, and use color or gradients to emphasize important points.

To get an uncluttered view of details, I typically put dimensions on a separate layer. That way I can see and/or print clearer views when necessary. As with all graphic programs, you have the ability to cut, copy, and paste. Within a CAD file you usually have different views of the same object. A feature called scaling makes it easy to create a suitably scaled overview of a project and, in another layer, have a drawing that prints life-sized details. This feature was put to good use in the following project.

This is the front view of a perpetual calendar made as a gift. The wood is cherry, a hardwood suitable to sharp details with good characteristics for turning in a lathe. The source was a neighbor's firewood pile, a well-seasoned, air-dried workpiece.

The display consists of four cubes, rotated to show the day, month, and day of the week. The characters were printed on transparencies and affixed to the blocks with spray adhesive. After some experimentation, I settled on yellow for the characters against the light colored wood to keep the appearance subtle. Black characters made it stand out from across the room; not my intent.

The turned pedestal was designed as simple cyma recta (two quarter circles) rotated 45 °. Only one half of the pattern is drawn. This is then grouped, selected, and mirrored about a centerline to get the full pattern. If I were interested in producing more than one unit; it would be a simple matter to print out the half-pattern at life size. From this a thin plywood template would serve as a turning aid to make duplicates. The full-size pattern for the main body was printed and affixed to the cherry block with a light spray of adhesive. The block was then cut out on a bandsaw allowing enough material to “dress to the line” by sanding on a stationary belt/disk sander.

The rest of the illustrations show the scheme to take care of our 12 month, {28 | 29 | 30 | 31} days per month, 7 days per week calendar year.

I have used CAD programs for more than a few years. In addition to designing furniture and shop jigs, I used an early version of TurboCAD to design a second story deck and carport that passed muster with the local Building Department. It may take you a while just to get started with an application; you must decide whether it is worth the time and effort. This article centered on wood working with CAD as a tool. CAD can be useful in many hobby fields: quilting, hooked rugs, stained glass, and model making– just about anything with a design of your own creation. Combined with digital photography, it opens a new world for creativity.