On Friday the wrong size bolt was used in the 1/2-13" holes used to clamp the HEPI frame to the BSC pier. This caused it to seize when the shoulder of the bolt got to the threads. When trying to back the bolt out it snapped with ~ 2 inches of threads left in the hole. After trying several methods of extraction (with no amount of success) a 27/64" bit (the same size used to prepare the hole for tapping) was used to drill out the bolt. The bolt cleared out, including the threads, for the most part and a tap was used to clean the remainder out. Enough thread was left to use a new bolt and clamp the HEPI frame to the pier (at 45 ft/lbs torque).

The pictures attached show the sheared bolt (photo 1) and the hole after being drilled out and re-tapped (photos 2 & 3).