Regular readers know that I am a big fan of both the Boy and Girl Scout programs. My children were scouts. My wife and I were scout leaders. One of the best things about the scouting movement is the opportunity to learn new things and to earn a merit badge testifying to your mastery of the required tasks. In some shops the workers wear badges on their shop coats to signify their increasing skill level. Perhaps we need to organize the Gear Scouts and award badges for each portion of the trade mastered. My last post covered the general types of gears that could be used to make a parallel shaft gear mechanism. People can spend their entire careers working with just one sub-set of those gear types and never have need to learn about intersecting shaft gears, skewed shaft gears, or gears with no shafts at all [racks, for those who are wondering]. One definition of an expert is, after all, someone who knows more and more about less and less. It has been my lot in life to work in a wide range of shops with many types of gears, products, and processes. This background proved to be a real asset in the consulting business, although it sometimes amazes me that so many unusual mechanisms find me. There is no need for everyone to be conversant in every gear type, but you should at least be able to recognize the difference between a bevel gear and a face gear and to know what applications would be good for a worm gear. Just as there are many options when designing a parallel shaft mechanism, an intersecting shaft machine could use a straight bevel gear set, a spiral bevel gear set, a spur face gear set, or a helical face gear set. Skewed axes can be connected by cylindrical worms, double enveloping worms, crossed helicals, skew bevels, hypoids, face gears, or several varieties of face worms. Even “shaft-less” racks can come in spur, helical, and double helical varieties. I haven’t even mentioned the non-circular gear possibilities either. Hopefully, you are beginning to understand just how complicated this “gear expert” game is. Please do not let it discourage you; we are here to help you learn what you need to know to succeed at the tasks before you.