Center drill bits, also known as combination drill and countersink bits, are specialized cutting tools used primarily to create starter holes and precisely located centers on workpieces. These holes are typically used as guide points for larger drill bits, ensuring accuracy and preventing the larger bits from wandering.
Short Length: Center drill bits are shorter than standard twist drill bits, providing greater rigidity and reducing the chance of deflection.
Combination Design: They combine a drill and a countersink in a single tool, typically featuring a pilot drill at the tip and a wider, conical countersink section.
Conical Tip: The tip is designed to create a precise starting point, usually at a 60-degree angle, which matches the angle of most lathe centers.
Material: Center drill bits are commonly made from high-speed steel (HSS) or carbide, providing durability and heat resistance.

Center drill bits offer following several advantages, particularly in precision machining and metalworking:
1. Center drill bits create a small, precise starting point for larger drill bits.
2. Center drill bits help in creating a small, centered hole that guides the larger bit, preventing it from wandering.
3. Enhanced Stability.
4. Extending larger drill bits lifespan and maintaining their sharpness for longer periods.
5. Improving Hole Quality.
5. Facilitating Subsequent Operations.
7. Versatility.
8. Cost Savings.

Creating Center Holes: Used to create accurate center holes in workpieces that are going to be turned on a lathe. The center hole helps to mount the workpiece securely between the lathe centers.
Starting Holes: Provides a starting point for larger drill bits when boring operations are performed on a lathe.
Precision Drilling.
Pilot Holes: Used to drill pilot holes for larger drill bits to ensure precise and accurate drilling, preventing larger bits from wandering.
Countersinking: The conical section of the bit can create a countersink to accommodate the head of a screw or bolt.
Setup Holes: Create precise setup holes on milling and machining workpieces to ensure accurate placement and alignment of subsequent machining operations.
Fixture Making: Useful in making jigs and fixtures where precise hole placement is crucial.
Marking Centers: Mark the center points for drilling in metalworking projects, ensuring that subsequent drilling operations are accurately positioned.
Deburring: The conical countersink can also be used to deburr the edges of holes after drilling.