Centre Drills are used with a lathe to centre drill stock for mounting in the lathe. They are designed to drill a small diameter pilot hole followed by a 60° countersink which provides a bearing surface for the 60° point of the lathe centre. Centre drills are also used extensively with milling machines to accurately start holes. The hole locations can be dialled in using the milling machine’s calibrated handwheels. The hole is then started using the centre drill. The large diameter shank on the centre drill holds the drill point right on centre. Once the hole is started, the centre drill is replaced with a drill of the desired diameter and the finished hole is then drilled. Sizes: No. 1 - No.