6pcs Combined Center Drill Countersink Bit Lathe Mill Tackle Tool Set Kit Features: and Resistance: Center drill bit is made of high-speed steel, with an extremely sharp blade, low consumption and with impact resistance, wear resistance. 60 countersink angle fits all standard centers. Wide Usages: Center drill bits can be used to make conical holes for a lathe center in order to make a starting point for a standard drill, designed to the drill from walking, as well as for producing center holes in components or Workpieces with requiring machining between centers. Available for all Kinds of Materials: Metal, Alloy, Copper, Iron, Wood, Aluminum, and so on. Specification: Each drill has a double end and is ground with a standard 60 degree angle The set includes 1 each of the following sizes: # 1 with 4mm body diameter & 1mm drill tip diameter # 2 with 4mm body diameter & 1.5mm drill tip diameter # 3 with 5mm body diameter & 2mm drill tip diameter # 4 with 6mm body diameter & 2.5mm drill tip diameter # 5 with 8mm body diameter & 3mm drill tip diameter # 6 with 12mm body diameter & 5mm drill tip diameter Instructions: Choose a match type of center drill bits according to the hole type and the straight hole size of the machined parts. The heat hardness of center drill bit is between 63-66HRC appropriate. Wash the rust-proof grease before using the center drill bit, so as to avoid chip sticking on the cutting. The surface of work-piece should be to avoid center drill bit being damaged. The center drill bit should achieve the required position accuracy before drilling. Package Included: 1 set of 6pcs Center Dril