Tapping MACOR ® MGC: Tapping Notes: 1. Make pilot hole one drill size larger than typically used for metals. 2. Use a lubricant while tapping. Lubricant can be hand applied. Tapping fluid or detergents both work well. 3. Tap to bottom of hole before reversing the tap. 4. Chamfer the entrance and exit of the hole prior to tapping to minimize ...