Now something very important. I will not move the frame at all. After a week has passed will solder the gantry and sides. Then will turn upside down the gantry and lay the upper side on the level surface of the epoxy. Then will pour epoxy on the gantry side plates that step on the Hiwin bearing blocks, connecting them together. Also pour epoxy on the lower side of the gantry beam. When dry, will turn the nagtry to normal position , rest the leveled side plates / epoxy on epoxy/ and pour the final epoxy at the top side of the gantry beam.
So with these steps i will achieve all hiwin rails lay on epoxy surfaces that are paralel to each other. The only thing left will be to ensure squareness of Z. I hope to achieve a quite precise machine.