It seemed like no matter how well I marked the centers of dowel ends, I could never get a perfectly centered hole. That all changed when I came up with the jig you see above. It not only holds the dowels in place for drilling, but it also has a built-in center-finder for marking the centers of the four most common sizes of dowels that I use. Simply press the end of the dowel into the matching size hole. The screw marks the center. Then clamp the dowel into the V-groove and drill the hole. The jig can also be used to drill cross holes in dowels by laying the jig on its side and clamping it down. The jig is made from a couple pieces of thick hardwood stock and two pieces of hardboard that function as a clamping surface. One note about constructing the center-finding block — drill the four shallow holes using Forstner bits. The tip of the Forstner bit leaves a small divot in the bottom of each hole. Use this divot to drill the through holes. The tips of the 1" screws should just protrude into the holes.