So here are a few more pages from "Mechanical Details For Product Design" Proper spur gear design can get confusing without an understanding of the terms and formulas used in there design. The first page is a clear layout of the terms and formulas used in designing spur gears.
Next is a couple of pages on designing for easier machining. Some are obvious,some not so much. Taking the time at the design stage can save time and frustration with less than great set-ups later.
For parts that will need heat treating, many of the rules used in castings also apply. Rounding internal and external corners and avoiding quick changes in section thicknesses will go a long way to preventing cracks and shrinkage problems such as warping.
So back to my breakfast, nothing special just some extra old, crumbly Canadian cheddar, on overly buttered whole wheat toast, washed down with a couple of cups of strong coffee, mmmmmmh. Cheers.