I bought a circular saw blade sharpener at yard sell the angle setting goes from 0 to 25 degrees how do I know what angle to set it at it does both steel an carbon tip blades chicago electric power tool model #96687

You match the tooth angles of the blade you are sharpening. See What you should know about circular saw blades (http://www.cabinetmakeronline.com/ViewArticle.aspx?id=13650) for angle recommendations. Harbor Freight Tools (http://www.harborfreight.com) sells this sharpener, you might be able to get a manual from them.