Start with a smaller pilot hole to guide the final bit

Drill a small-diameter hole first, then enlarge it to the final size. The pilot hole physically guides the larger bit and prevents wandering.

Steps

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

Why It Works

A smaller bit has less contact area, so its cutting edges engage quickly with minimal wandering. The pilot hole then acts as a centering channel for the larger bit's chisel point.

Tips

• The pilot hole should be at least as large as the web thickness (solid core between the flutes) of the final bit.
• On metal, use cutting oil on both passes to reduce heat and extend bit life.
• A step drill bit (unibit) progressively enlarges holes in one tool -- ideal for sheet metal.