The primary reflective surface of the Large Millimeter Telescope (LMT), it will be formed by a set of trapezoidal panels. Each panel has a paraboloid off-axis form and it is constructed with carbon fiber. The paraboloid off-axis surfaces is obtained copying by contact to a mold with the required form. One proposal in order to manufacture each mold, is made it of graphitizing steel fused. And after that, it lathing with a numerical control machine for obtain the paraboid off-axis section. But due to the dimensions of the sections, 5x3 meters for the biggest section; the mold of steel will be formed by two small segments. In consequence, it is necessary in the first place, alignment these segments in order to obtain a mold with a surface approximately continuous, with a minimum precision of 5mm. In this work we present a method in order to alignment these two molds' segments, as well as, the results of alignment obtained for the prototype mold.