Step 2 is developing proper orientation with the world. The work table is first shimmed up to be level on both axies. Pieces of frog plate which will be the base are placed on the table, the I beam is then hoisted up and very carefully lowered to sit on the frog plate pieces. None of this stuff is particularly straight, so orienting it with the world is done with a spirit level, a little gringing in the appropriate place, and some well placed shims.