To prevent the cement from cracking, the hole has to be big enough to allow a ½-inch clearance between the side of the post and the side of the hole at every point.
Resources
A custom metal railing can be purchased from a welding shop. Mark recommended using one with solid steel posts. The one Mark installed was made by Mike’s Welding Company. All the materials Mark used for this installation, including the caulking gun, the anchoring cement, and the coring drill, can be found at home centers. Expert assistance for this segment was provided by MJM Masonry.