Use a spring-loaded automatic center punch
Place the pointed tip of a spring-loaded automatic center punch on your marked drilling location and press down firmly. An internal spring mechanism fires a weighted striker that drives the tip into the material, creating a precise conical dimple without needing a hammer. The dimple gives the drill bit a seat to register in, preventing wandering on the first rotation.
Why It Works
The spring mechanism delivers a consistent, controlled strike every time. Unlike a manual center punch where strike force varies with each hammer blow, the automatic version produces a repeatable dimple depth. The tool requires only one hand, leaving your other hand free to hold the workpiece. This is particularly effective on metal, stainless steel, and hard plastic where even slight bit wandering can ruin a project.
Tips
- Adjustable models (like the General Tools 78 or Starrett 18A) let you dial the strike force from light to heavy -- use light force on thin sheet metal to avoid denting through, and heavy force on thick steel plate
- Hold the punch perpendicular to the surface -- tilting it creates an off-center dimple that guides the bit at an angle
- For very hard materials like hardened steel or porcelain, make two strikes in the same spot for a deeper dimple
- Press the tip firmly against the surface before triggering -- if the tip is not seated, it will skip sideways
- Cost ranges from $5-8 for basic models to $25-40 for precision machinist-grade tools
- Common mistake: using the punch on glass -- it will crack; use tape method instead for glass