Center punches

The center punch is a machinist’s tool that the woodworker occasionally finds useful for marking hole locations in metal and wood. The simplest model is a hardened steel punch, much like a pointed nall set, which is tapped with a hammer to creat a dimple preparatory to drilling.
An automatic center punch has an internal trip spring that is released by pushing down the top of the punch. To regulate the force of the blow you turn the cap to adjust the spring pressure.
Center punches are available at your local hardware store and through industrial supply catalogs.