Machine Design

Illustration software helps design manuals

Good technical documentation complements a good product.

Rick Elliott

A photo can be the "first-pass" illustration when building a document. When the product is finalized, it's a simple matter to replace the photo with a line drawing.

The Object Manager shows an ungrouped screw made up of 14 objects, all curves and ellipses. Curves represent the threads and ellipses make up part of the head and the end of the screw.

Moving a grouped PCB (the dotted square) close to a line shows the snap location it will lock to, in this case the midpoint of the line.

A guide line (the straight line) is used to line up callouts for a more orderly presentation.

For example, service manuals often include exploded diagrams so technicians can see how parts fit together in machines. Other manuals provide users with helpful illustrations and operating instructions. Part of my job as a technical writer is to generate such manuals. The tool of choice for illustration is CorelDraw Graphics Suite 12 (a more recent version is available). I regularly use the CorelDraw component for drawing and the Capture component for editing screenshots. This review focuses on CorelDraw.

Most jobs I've held in the last 10 years required the technical writer to create drawings for documents. Thus, the writer must find the best way to work with designers and engineers. I typically ask designers to rotate part models to certain views in CAD and lock the views to isometric parameters, or 30, 60, and 90° angles.

CorelDraw is vector based, so users can import AutoCAD drawings and make changes directly to them without loosing any definition. Users can also import JPEGs, TIFFs, and raster formats such as BMP. In addition to AutoCAD, our document-creation process involves FrameMaker, a widely used program for generating manuals. So I usually import DXF files into CorelDraw, save them as Windows Metafiles (a vector format), and then import these into Framemaker.

A particularly handy feature in CorelDraw lets users add layers to drawings. For example, I often use photos as "first-pass" illustrations in a document. Then when the product or procedure is finalized, it's a simple matter to replace the photo with a line drawing or flowchart. Or say the image is a circuit board. I add layers for labeling the board's parts. Individual layers can then be turned on or off, locked, or printer disabled.

A recent application involved writing a user manual for a technical instrument. For one illustration, I imported the two necessary AutoCAD files and put each drawing on a separate layer. One layer held the cabinetry image and the other held the circuit board with the cable coming out. I split the cable so it looked like it is going under the board. A good trick to note: a black line placed on top of a bigger white line makes it seem as if the black line flows over everything. A similar task places a part made of complex shapes on top of a filled polyshape with the same outline. This gives the illusion that the part is on top of everything without trimming all the lines.

In another case, an imported exploded view showed parts in the proper orientation. But there was no indication of what part goes where or whether fasteners are needed. So I add a layer, named it Screws, and drew the screws. The Object Manager to the right of the work area lets users look at every shape or object in a drawing. When I select a screw in Object Manager, the software highlights the group of objects making up the screw. A screw in this case is made of 14 objects, curves and ellipses, which have parameters such as line thickness and outline color. Rotating a screw is merely a matter of double-clicking on it and pulling the rotation handles.

Next comes placing callout leader lines and making callout circles for part numbers or other data. I snap the callout lines one at a time and lock them perpendicular to the appropriate circle. A convenient feature of the line tool puts arrows on the ends of the lines.

Exploded views such as described above are typically used as a parts list for a manual. After I finish the screws and save the drawing, I import it into FrameMaker and insert a table with four columns near the illustration. One column holds item numbers corresponding to callout circles. The next column holds item descriptions such as a front panel, rear panel, or circuit board. Another column holds part numbers and the last holds quantities required.

On the downside, CorelDraw does not have built-in isometrics as do higher-end drawing programs such as AutoCAD. And it does not have as many snapping options. However, CorelDraw is an excellent program for its capabilities, ease of use, and low cost.

The software comes from Corel Corp., Ottawa, Ontario, Canada, (800) 722-6735,

Rick Elliott is the owner of CTTK Communication LLC, Akron, Ohio, (330) 535-8750. He can be reached at [email protected].

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