When I received the extrusions from 80-20 for my Pro4824, I spent time checking each piece with a machinist square and feeler gages. Each part was cut very accurately as to length and squareness. I spent a lot of time using squares, clamps and measuring to insure the base was as square as possible during assembly. When finished the gantry was less than 1/64" out of square. I made a very slight adjustment during the squaring procedure. Since I do mostly woodworking that's as far as I went. That was 2 years ago and the cnc still cuts square enough for me. I don't think you will have any problems although I'm sure there are members here that do far more accurate work than I who will give their opinion.