Sherline 3-piece Center Drill Set Can be used with the lathe to drill a hole Designed to drill a small diameter pilot hole Drills are also used extensively with the milling machine The Sherline 3-Piece Center Drill Set is used with the lathe to drill a hole at the end of stock for mounting between centers in the lathe. They are designed to drill a small diameter pilot hole followed by a 60° countersink that provides a bearing surface for the 60° point of the lathe center. Center drills are also used extensively with the milling machine to start holes accurately. The hole locations can be dialed in by using the milling machine’s calibrated handwheels; then the hole is started using the center drill. The large-diameter shank on the center drill holds the drill point right on the center and keeps it from “walking” as the hole is started. Once the hole is started, the center drill is replaced with a drill of the desired diameter and the hole is finished. CAUTION: It is imperative that a cutting lubricant is used, and the center drill is backed off several times to prevent the smaller tip from twisting off.
