Gear Design: More Than Pretty Pictures

Courtesy Wikimedia

No one has a drafting room anymore and that is not a bad thing. Where dozens used to labor for weeks preparing detailed drawings of each component of a new machine, a couple of people with personal computers and a printer can easily produce the drawings in a matter of hours. And what beautiful drawings they are; every line crisp and well positioned, all the text wonderfully rendered. Sections will be accurate and many drawings will have isometric views we could only have dreamed about in the good old days.

            But in all this “progress” lies a great danger. I once had a co-worker who had the goal of a completely computer-generated gearbox drawing package. He wanted to input the basic numerical description of the product on one end of the process and have a full set of drawings and calculations spit out of the computer. Sounds like the sales pitch of a current high end 3-D design package yet he was working on it twenty years ago.

            In those days the computer power just was not available to do this well but even more importantly, the best code he could write could not cover all the issues that would come up. One famous experiment produced gears that collided with other shafts in the housing and management lost confidence in the program.

            That drafting room crew might have been slow, but they were thorough. Many eyes looked over every drawing and most mistakes were caught before they cost serious money. My fear with the modern design packages is not so much that they would produce an M.C. Escher-like part that cannot physically exist but rather that they are so efficient and reliable that no one checks the design and details thoroughly.

            Drafting room culture depended upon people looking for mistakes. If someone let a drawing out that had typos or tolerance errors everyone heard about it. You did not want your name associated with scrap, either as a drafter or a checker, so you reviewed your work carefully and learned to accept criticism with a good attitude. Better a quick drawing change than the stigma of letting something slide by.

            Do not let the errors built into that box of chips tarnish your reputation as a designer. Check the output like it was done by a rookie draftsman who could barely keep a pencil sharp.

About Charles D. Schultz 640 Articles
Charles D. Schultz is President of Beyta Gear Service and one of Gear Technology's technical editors.

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