TH650 bare machine is integrally formed by precision casting through HT250 cast iron resin sand cores. The DX650 bare machine is difficult to deform because the gantry and the stanchion are integrally cast and are totally aged and the rigidity is large. The guideway and the screw rod are produced by Hiwin, wherein the guideway adopts HGH30HAH lengthened overloaded sliding block and is pre-tightened, with the mounting surface being fixed by a strong approaching block, so that the precision is not influenced because the guideway is not loosened under vibration. The screw rod adopts C3-grade pre-tightened grinding ball screw rod, with two ends being fixed and pre-stretched, so that the error owning to temperature increment of screw rod is eliminated. All bearings are imported bearings in pair and are matched with national well-known automatic lubricating devices. The stainless steel protective shield is provided in Y axis. All precision items shall strictly comply with the national standard before leaving factory. The appearance of bare machine shall be painted with required colors. The bare machine does not contain any electrical apparatuses.