The traditional method for producing post holes or slots in concrete slabs is to insert a metal sleeve in to the fresh concrete, wait for the concrete to set, and then place the posts, handrail sections, or other inserts in the slots and secure them. An alternative approach that often is faster and more accurate is to drill the desired holes into the hardened concrete with a diamond core bore bit at precisely measured intervals. The standard drilling rigs used for this operation are capable of boring holes up to 8 inches in diameter in reinforced concrete. They are sufficiently light and portable that an operator can move from one location to another, drilling holes without assistance. Operators having no previous experience with this type of drilling normally become proficient in less than a day. The average length of time required to drill a hole 2 and one-half inches in diameter and 6 inches deep is approximately six minutes, or one minute per inch of depth. Removal of the core is easy and simple. When the bit reaches full depth, the core often breaks off within the bit. If not, it can be removed by slight rapping so that it breaks off at the base; it is then lifted out.