Canadian Woodworking

Design your own projects with CAD

Author: Michel Theriault
Published: August September 2003
Design with CAD
Design with CAD

There are really two parts to designing your own projects. The first is the drawing itself, which is made easier with CAD (Computer Assisted Design).


Why design your own projects? Using plans is OK, but what about something you can’t find a plan for? Or what if you have a unique need that no one has designed a project for? Designing your own projects solves these problems. In fact for some, designing a project is almost as much fun as building it.

One advantage to designing your own project is that you can make the project match your ability and the tools you have available. It also allows you to maximize your material, by changing dimensions as required and by dressing the boards you have down to a different size. This will save you both time and money.

The second is how the parts go together – the joints. If you haven’t designed anything yourself yet, pick up a book of joints to give you detailed ideas on how to put the parts together.

If you still build most of your projects from existing plans, you can use CAD to simply modifying those plans to meet your specific needs. You can use CAD to change the dimensions or construction methods to suit your needs. You can even add, change, or delete decorative elements/detail from the final product and be confident that the rest of the project will still fit together properly. Once you become comfortable with typical construction techniques, you can begin designing your own projects.

How does CAD help you design projects?

CAD allows you to use your computer to draw what you might otherwise draw on paper. If you have avoided designing your own projects because you feel you can’t draw a straight line, CAD is the obvious solution. With it, you can draw with exact precision, and use drawing tools that add an incredible amount of flexibility and efficiency to your drawing time.

To help you build the projects you design, a CAD drawing measures and labels the dimensions of anything on your plan, providing you with an accurate cutting guide. You can also print out the full project on a single piece of paper. When you need a pattern to transfer to the wood, you can also print parts of it to full scale.

If, for any reason, you want to change the design, CAD makes those changes easy to do. With paper, you would have to erase and re-draw the change and anything else affected by it. With CAD, the changes are easy to make. If you want to keep the original and see how your changes will look, you can do that too. A good example of what you can do is design a coffee table, then shrink its length to make matching end tables.

Depending on how you like to work, you can either draw the project in full detail or simply draw the basics. Full detail shows the hidden parts and all the details are fully fleshed out. The basic drawing gives you information, such as the lengths and widths of various parts for cutting, and leaves other details for you to decide during the building process.

Drawing with CAD is very similar to drawing on paper, with a few exceptions. For the most part, you need to plan ahead when drawing (for example: using the last end point of a line as a starting point for the next line). With most programs you don’t need to worry about scale until you want to print – you draw in real size and either zoom or shrink it to fit the screen while you draw.

Because of the precision of a CAD drawing, you must be careful to ensure that the size of the lines, rectangles, etc. is exact. Fortunately, that is very easy to do in CAD. You can usually specify the exact dimensions of each piece you draw. For instance, to draw a drawer front, select the rectangle tool, select a point on the drawing for the first corner and either type in the dimensions (i.e. 13 ½” wide by 3 ½” tall) or simply drag the rectangle and the display will tell you the exact dimensions as you drag. Alternatively, you can set up a grid on the drawing (perhaps spaced ¼”) and then “snap” the lines and corners to the grid as you drag the shape.

If you have to draw several identical items, such as a joint or drawer, you can draw it once and either copy it to the new location or even rotate it or mirror it. The mirror function allows you to draw one end of a project and then flip it over and position it at the other end, completing the drawing with half the work.

Types of CAD Drawings

Computer Assisted Drawing allows you to easily produce the two basic types of drawings you would otherwise use pencil and paper for. These are simple 2D and isometric 2D drawings.

2D is used for typical plans and is drawn on a square XY grid to represent height and width. The drawings show only one side of the project at a time, and usually a plan is made up of multiple views (such as a top view, side view, and end view). These are laid out in a logical format so you can visualize the project (fig. 1).

Isometric drawings give a 3D type of view using a modified angular grid. This allows you to show three sides of a drawing in 2D, however the sides won’t be seen in a standard square format – they will be angled (fig. 2).

A 3D CAD drawing also uses a square XY grid, with a third Z dimension added to indicate depth. This allows a full visualization of the completed project. Often the software allows you to add surface texture to the drawing, rotate the project and view it from any angle. This is usually quite a step-up from 2D drawing both in cost of the software and the level of difficulty in drawing the project. Visually, it looks very much like an isometric drawing, with the added benefit of being able to turn hidden lines on and off and rotate the drawing to view or print any angle.

For most home woodworkers, a 2D CAD program is sufficient, with 2D isometric capabilities as an added bonus.

What else can you do with CAD?

While there are specialized CAD programs for things such as designing a house or landscaping your garden, any CAD program that you consider for woodworking can also help you design floor layouts, sheds, and even landscaping projects. You can also use it to figure out how to lay out pieces to be cut on a piece of lumber or sheet of plywood, ensuring the most efficient use of the material you have.

CAD Programs

CAD software is available at a wide variety of prices and capabilities. Here is a list of packages you may want to consider. The price range is about $100 – $250:

• QuickCad, Autosketch –

• DeltaCad –

• TurboCad V8 –

• IntelliCad Standard –

Next issue, Michel gets more detailed with specific CAD programs and highlights their strengths and uses.

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