Emory Kimbrough writes: “Here’s a method for finding the center of a dowel or any solid rod that will fit into a drill or drill-press chuck. Besides the drill or drill press, it uses only sandpaper. A lot of center-finding methods that use pencil-and-straightedge geometry or store-bought center-finding gizmos become hard to use and inaccurate on small-diameter rods, but this method excels with the skinny little workpieces.
"Just place the rod into the drill chuck and spin the end of the rod against the sandpaper. The sandpaper will scratch a bulls-eye pattern of concentric circles in the rod’s end, revealing the center. Center-punch the bulls-eye and you’re ready to drill into the cylinder’s axis.
"This works for both wooden and metal rods. If the concentric rings aren’t as distinct as you’d like, try a different grit of sandpaper. In the left photo above, some ½” aluminum round stock is being spun in a drill press against some coarse sandpaper glued to a wooden block. In the right photo, you can see the concentric circles sanded into a wooden dowel.”