Here is the perfect way to drill nuts and bolts for use with safety wire 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".
The SAE fixture bar is threaded for 1/4"-20, 5/16"-18, 5/16"-24, 3/8"- 18, 3/8"-24, 7/16"-14 bolts, and the Metric fixture bar covers M6x1.0mm, M8x1.0, M8x1.25mm, M10x1.25mm, M10x1.5mm, M12x1.5mm sizes.