shaft 20 which has a thru hole 20 b at the extreme top to receive a roll pin 46 that is the retainer for spring 41 that applies pressure onto knock out pin 40 that is restricted from coming out of the shaft 20 by partially a exposed roll pin 47 protruding to the inside hollow 20 c of the shaft 20 hole 20 a is positioned to align with the lower inside of the oil and coolant tank just above the lower seal 42 and allows oil to continue into and down the main core drill shaft 20 onto the top of the core drill bit 54 core drill and when the pin 40 is compressed against the spring 41 oil is allowed to flow into the core drill bit 54 and onto the materials being drilled or lathed while using the cda 300 for turning purposes snap ring 44 fits into snap ring groove 20 d in main shaft 20 to hold parts in place nylon washer 43 runs under snap ring to protect rubber o ring seal 42 below washer which restrains oil and coolant fluid from escaping from top of tank 310 the cda head 24 shows a roll pin 46 in the top extremity this roll pin 46 inserts into a partially drill hole 23 a shown in fig2 b being the bottom cover of reservoir 23 shown in fig2 b which allows rotation of the tank along with the cda 300 this rotation causes the tank 310 portion as a unit to become a harmonic balancer to reduce vibration while the machine is working also note that core cda head 24 has a machined slot 46 a cut into the inside to allow oil and coolant to.