In my last post I insisted that good design wins in the marketplace. As a student of automotive history, I am compelled to admit that some very great designs were failures on the sales front. Clearly, design quality is far more than just physical appearance. In the gear trade, form has definitely followed function; not since the legendary Falk Y unit has a manufacturer touted having an independent industrial designer massage their product to achieve a more artistically appealing shape. Yet anyone who has been around a while can recognize some products from twenty feet away. Machine tool makers put a great deal of effort into the “look” of their products. So much so that when World War II required them to take short cuts, they insisted upon putting an apology to purchasers on each one in the form of a brass tag. There was little incentive to worry about appearance when I was designing special one-off gearboxes. Rarely could I bring myself to proceed with a truly “ugly” design. There is an old saying that if it doesn’t look right it probably isn’t. That presupposes a trained “eye” in the observer though, and how do you train someone in that skill? This is a growing concern as high-powered CAD programs allow even novices to make pretty 3-D renderings that may or may not be “good” designs. So what separates good design from bad design? On the basis of over six hundred custom gearboxes, I would boldly offer the following:

• Adherence to specifications. If it doesn’t meet the specs it might as well be a sculpture.
• Compliance with standards. AGMA standards have been developed with warnings on many things that can cause problems in service. You had better have a very good reason to ignore these warnings.
• Ease of manufacture. Mechanisms that require tolerances beyond the process capability of your equipment do not inspire confidence.
• Ease of assembly. Special tooling and fixtures have their place, but seldom add value. Certain bearing types do not like to be pushed into a bore axially. Wrench clearance, access for inspection, and room for modifications later are important considerations.
• Minimal part count. Part count drives cost; is that spacer really necessary?
• Symmetry is your friend. You do not need a degree in Art to know asymmetry upsets the brain. No matter how you note it on a drawing, for example, unequally spaced holes frequently get put in symmetrically because our brains are hard-wired to make things “balance out.”