This spreadsheet will generate bevel and miter gears adequate for most applications around a home shop. To use the spreadsheet it must be downloaded to your computer.
A little history. Regular bevel/miter gears cannot be accurately cut on a milling machine and are usually generated on special machines. In 1913 the Parallel Depth method was created and was used extensively in WW1 to make up the short fall in bevel gear production. Parallel depth gears have a shorter but parallel tooth form and can be machined adequately on a milling machine. Parallel and regular bevel gears cannot be mixed. Since regular bevel gears, of a given Diametric Pitch, have a Pitch Circle measured on the large side and parallel depth bevel gears have the pitch circle measured on the small side, it is necessary to reduce the number of teeth to get a gear the same physical size. Compare gears sizes from a gear catalogue with the dimensions generated by the spreadsheet with the same number of teeth. More information on bevel/miter gear construction, in the home shop, can be had in the book Gears and Gear Cutting by Ivan Law. There are several YOUTUBE videos on cutting bevel gears in the home shop.
Click on link to view a representative non-functioning Excel spreadsheet.
To download - Open link and click the download tab at the top of the page and follow instructions.
To Use - Input the number of teeth and the Diametric Pitch of the gears.
https://drive.google.com/file/d/0B4Rjw2WCtrGzZ0M0LUNvWE1EX2c/view?usp=sharing