Step 2: Cambiar la correa del variador (changing drive belt)
The one I used originally, after failing my attempts to make myself a belt, was –as I explained at the time– of an appliance purchased. It worked well, but it was flat, which limits the variation range of speed. To understand why that was, imagine that the belt is the width of the cones: in this case the variation would be zero. After some research and be lucky to find a knowledgeable person on the subject, I bought a few pieces of nitrile band of 7 mm circular section, especially suitable for what I needed. I cut a piece of suitable length, ends on a fairly sharp angle, in order to increase the bonding surface. Heat a piece of metal in the flame of gas, I assured it vertical clamp and a rubber band to have both hands free, and supporting the ends of the piece of nitrile, waited two or three seconds until melted. Then, quickly joined and waited a while for it to cool.