90° 30TPI Right Hand Spiral Knurl

Center drills are essential for accurately drilling starter holes in the ends of workpieces, particularly when mounting stock between centers on a lathe. Each drill creates a small pilot hole followed by a 60° countersink, which provides a seating surface for the 60° point of the lathe center.

In milling applications, center drills are commonly used to start holes precisely. The exact hole location can be dialed in using the mill’s calibrated handwheels, and the center drill ensures the hole begins accurately without drifting.

This set includes three double-ended, high-speed steel (HSS) center drills:

• #1 drill: 1/8" shank

• #2 drill: 3/16" shank

• #3 drill: 1/4" shank

The larger shank diameter of a center drill ensures the tip remains centered, reducing the risk of the drill "walking" as the hole is started. After the center drill has established the starter hole, it is replaced with a standard drill bit to complete the hole to the desired diameter.

⚠️ CAUTION: Always use a suitable cutting lubricant and back the drill out frequently during use. This prevents the delicate tip from overheating or breaking off.