This onsite footage from 02011 shows the completion of the 500 foot deep vertical shaft for the 10,000 Year Clock in West Texas.
We used a mining technique called raise boring to create the 12.5 foot diameter shaft. Instead of drilling down from the top, a large diameter reamer was pulled up from the bottom to the surface, starting from a smaller diameter pilot hole. It's more efficient than a top-down drill because the rubble isn't fighting gravity. It rains down beneath the advancing bore and gets hauled out a horizontal shaft at the bottom.
Following this work, we began to cut the spiral stairway into the walls of the shaft using a robotic stone-cutting saw as well as the manufacture and testing of the full size Clock components.