Mechanical testing machines are widely used and necessary in the Industry for acquiring the mechanical properties of various materials, aiming varied result applications. The design of the tensile testing machine covered here, will be presented a gantry structure using a mechanical jack as the lifting unit. Here will be approached all the process of dimensioning and construction of such an equipment and the constructed prototype will have maximum capacity of 5 tons. It will be also designed to stiffness, targeting no greater deflections than 0.001 mm in order to fulfill its purpose. The model will, afterwards, be validated through computational simulations using the finite element method.