It’s common to get a diamond core drill bit stuck in the material which is being cut. To avoid this happening, ensure you: – Always use water. – Clean the core hole often. – Don’t try removing too large a core. – Have good water pressure, which helps flood the sediments up to the top of the hole and relieves the pressure on the core bit. In the instance where a core drill bit is stuck on drill, use channellock pliers on the core and put a spanner on the drill shank. Turn the spanner counter-clockwise and it should free the core. If this is still proving a challenge, spray WD-40 lubricant on the area, and allow it to penetrate before trying to free the core.