How to Make a CAD Drawingby Ellie Maclin
CAD, or Computer Aided Design, is a mix of computer hardware and software that allows an engineer or technical designer to draw complex scaled drawings to particular specifications. In addition to the necessary CAD software, a CAD system must provide high-quality digital imagery via a good-to-excellent quality monitor; highly accurate printing to scale, often via a specialty printer; and the means to input data, either via scanner, light table, or light pen. CAD is also known by the acronym CADD, or Computer Aided Design and Drafting.
Choose your software. The software you pick may be based on your needs and your budget. Basic 2D drawings and even some 3D functionality are available in many freeware/shareware programs and affordable mid-range software such as DesignCAD. For advanced 3D modeling and very complex layered plans, a high-quality CAD software such as AutoCAD is a must.
Acquire and set up your hardware. Your work station should allow space to work with hard-copy plans as well as your digital screen. If you will be using a light table (also known as a digitizing tablet) or light pen, place those pieces of hardware so that you have room to utilize them, and connect them to your computer. If you are using a large map scanner and/or smaller tabletop scanner, place it appropriately and connect it to your system. You will need at least one of these options if you need to convert hard-copy plans or maps into digital format, known as digitizing.
Understand the basics of Computer Aided Design. At a minimum, you must be comfortable with concepts of scale; be able to understand and use layers, which allow you to categorize information so that you can see or hide particular visual data sets at will (for example, all the pipes in a house); and be able to conceptualize 2D and/or 3D shapes, depending on your needs.
Set up your chosen software and familiarize yourself with the tools. Utilize any manuals or tutorials that come with the software. You must be able to set the scale (tell the computer how big to make the components of your drawing), and be able to draw 2D and/or3D shapes, depending on your specific needs. CAD softwares can be temperamental about the order in which you complete the steps in your drawing, so make sure you are comfortable with the tools and program design before you begin your drawing.
Acquire your beginning data. If you already have digital files, your job will consist of importing these files into layers. Depending on the format and organization, you may be able to use these existing files to complete your "drawing." If not, you can use these files as the basis for your drawing, or as a basemap.
Create your file. This will be the CAD file, with a proprietary file name based on the program, that houses all the layers of your drawing. Create and save the file first, and every time you make a change to a layer.
Create your basemap(s). The easiest way to do this is to scan a map or image and place it in a layer. Do this with all applicable information. For example, if you have different plans of a property showing the locations of pipes, property lines, and structures, and want to create one final drawing, you must scan or digitize each plan as a separate layer. Make certain that each scan is adjusted to scale.
Digitize all the necessary data, creating a new layer for each type of information. If your base data is in hard copy form, such as maps or architectural plans, you will need to digitize the data in one of two ways: use a light pen or light table to digitize points, lines, and polygons directly from the paper form; or scan the hard copy and use the CAD program to draw points, lines, and polygons on the screen, known as "heads-up digitizing." In our example, use each basemap of pipes, property lines, and structures to create three more layers: one for digitized pipes, one for digitized property lines, and one for digitized structures.
Customize the information as desired. You can "turn off" the layers containing basemaps, hiding the original information and showing only your digitized layers. You can change the colors of your points, lines, and polygons, or create 3-dimensional models from your basic, layered forms. Add basic cartographic information, such as scale, title, date, and illustrator (you or your company).
Save and print your final drawing. Be sure to double-check your printer settings so that your drawing prints to scale. If scale is of supreme importance, as in architectural or archaeological drawings, you may wish to double-check your scale with a ruler to make sure that your printer is right on target.
- check CAD programs require a concept of the drawing as a 'layercake' that you build one well-designed layer on top of another; make sure you are prepared and understand the virtual "architecture" of Computer Aided Design.
- close Double-check your scale. Make sure that each basemap is adjusted to the same scale, and that each digitized layer reflects the appropriate scale. If your scale is incorrect on even one layer, your final drawing will contain mistakes.
Items you will need
- photo_camera Comstock/Comstock/Getty Images