This presentation was made by John Lovegrove, as a seminar at the 2015 N.A.M.E.S. Expo, on how to design and machine cams for small/model engines. The first link is a PDF of the presentation and the second is an Excel spreadsheet, four pages, with calculations (pictorial representation only, download for functionality) that accompanied the presentation. Both are downloadable by using the download icon at the top of the page and then following the download directions on the page.