I have recently bought a generic,110x520 lathe "fervi",must be chinese,it has a set of changewheels;21-24-30-35-38-40-42-45-50-55-60-63-65-80-100,I would like to be able to cut threads(mainly metric) but there are no diagrams or lists of any sort,can anyone help?,I have a book with the formulas but I can't get my head round them as yet.I am a wood turner and guitarmaker,but I want to try my hand at metal turning.