OTC 4794 Safety Wire Drill Guide Set, SAE and Metric Set
Here is the way to drill those nuts and bolts for use with safety wires without breaking the drill bit. These guide, align, and support the hex head or the bolt threads. The hex fixture fits nuts and bolt heads that measure up to 1-1/4 inches. The SAE fixture bar is threaded for 1/4 inch-20, 5/16 inch-18, 5/16 inch-24, 3/8 inch-18, 3/8 inch-24, and 7/16 inch-14 bolts. The metric fixture bar covers M6 x 1.0 millimeter, M8 x 1.0 millimeter, M8 x 1.25 millimeter, M10 x 1.25 millimeter, M10 x 1.5 millimeter, and M12 x 1.5 millimeter sizes.