Step1: When drilling starts, the system drives the casing shoe and casing tube move down.
Step2: When reaching the bedrock, lift up the block system, the blocks will closed, reverse rotation and pull out the block system from the hole.
Step3: If the hole have reach the desired depth, finish the drilling and continue other process.
Step4: If you still want to drill deeper, use the conventional DTH bit to drill to the desired depth.
