Start with a smaller pilot hole to guide the final bit

Drill a small-diameter pilot hole first, then enlarge it to the final size with a larger bit. The pilot hole provides a physical guide that prevents the larger bit from wandering.

How to Do It

1. Mark the desired hole location and optionally use a center punch or tape to prevent the pilot bit itself from slipping
2. Select a pilot drill bit significantly smaller than the final hole size (e.g., 1/8-inch pilot for a 1/2-inch final hole, or 1/16-inch for a 1/4-inch final hole)
3. Drill the small pilot hole at low speed with steady pressure
4. Switch to the final-size drill bit, place its tip into the pilot hole, and drill at the appropriate speed for the material
5. For very large final holes (over 1 inch), step up through 2-3 intermediate sizes rather than jumping directly from a small pilot to the final size

Why It Works

A small-diameter bit has less contact area with the surface, which means the cutting edges engage more quickly with less tendency to wander. Once the pilot hole exists, it acts as a physical channel that centers the larger bit. The larger bit's chisel point drops into the pilot hole rather than skating across the surface. This technique is especially important on metal, where larger bits generate more lateral force and heat.

Tips

• The pilot hole should be at least as large as the web thickness (the solid core between the flutes) of the final bit -- this ensures the larger bit's cutting edges engage cleanly
• On metal, use cutting oil on both the pilot hole and the final drilling pass to reduce heat and extend bit life
• Step drilling (incrementing through 2-3 bit sizes) produces cleaner holes with less burring than jumping from a tiny pilot to a large final bit
• A step drill bit (unibit/cone bit) is a single tool that progressively enlarges holes through multiple diameter steps -- excellent for sheet metal and electrical boxes
• For holes in hardwood, a pilot hole also prevents the wood from splitting when the larger bit pushes through
• Common mistake: drilling the pilot hole at an angle -- the final bit will follow the same angle, amplifying the error; use a guide block if perpendicularity matters