Today, I worked on the four carry thoughs, #5-8. I made a jig of blocks on the table that I put the carry though over and then pushed it against and held in place with two shims and pony clamps. I pre-drew the vertical lines and put blocks in place to hold the uprights level. The width was exactly 44 inches outside to outside. Prior to and after drilling the first hole, I double checked the square. For number 8, I needed to make doublers out of .032 material.
Prior to this, I did check my square to make sure it was good. Not all squares are square.