We have now spent over half the year reviewing fundamental concepts in gears. Knowledge is just trivia unless you put it to work; it can be a bit of a “which came first” situation where your needs require you to acquire new skills or new information inspires you to attempt new tasks. No matter what your present job duties are, it is helpful to understand what other people on your team do also. I did not set out to design custom gearboxes. A series of career moves put me in a position to apply the things learned along the way and, over time, I was responsible for over 600 custom gearbox designs. It worked out to almost one project a week for twelve years so it was important to establish a consistent thought process and to keep good records. No matter how hard you try, you will not be brilliant every day. But a proven methodology will allow you to avoid repeat mistakes and to learn from the mistakes of others. When new methods or calculations are developed, you can quickly incorporate them into your routine and be confident that your designs are going to work. Some of the information in the next sequence of postings may seem familiar to longtime followers. The design process is a favorite subject for me, in part because it is not taught in school. We got classes on specific portions of product design, but even group design projects did not illustrate the “give-and-take” needed to create a successful device. That “give and take” is what separates the great from the merely acceptable. People love to complain about the awkward spots “those engineers” put them in without considering the limited options that may have been forced upon the development team. A great example of this can be found in the frequent complaint that it is impossible to change the spark plugs in vehicle XYZ without unbolting the motor mounts or removing the glove compartment. The designers probably argued with the marketers who insisted that they shoehorn that massive powerplant into that tiny engine bay only to be reminded that the customer demanded it. We have similar situations in gearing all the time. A well honed design procedure gives you more time to figure out that trick access cover.