Drill dead-on dowel joints

Dowels dramatically increase the strength of many joints. But this seemingly simple joinery method can be unforgiving: Misalign one dowel hole by a fraction of an inch, and you might as well miss it by a mile—the joint simply won't go together. To prevent that from happening to you, we present here solutions to three common doweling problems.

But first, consider these essential tips to improve the accuracy of your dowel joints.

• Mark locations with a marking knife or sharp pencil. A fat pencil tip robs you of precision.
• Use sharp brad point bits instead of twist bits (because you typically drill dowel holes on end or edge grain, which encourages twist bits to wander).
• Mount a stop collar to your bit to get consistent hole depths. (Drill ¹⁄₈ " deeper than one-half the dowel length.)

Problem: My edge-to-edge joint fits together, but the faces are not flush.

Solution: The jig's guide holes may not be centered between its faces. Always reference the jig against common faces of each mating piece (shown below). Do so, and though the holes may not center in the boards' thickness, they will line up.

Problem: After drilling the edge of one board, I'm having trouble duplicating the hole spacing on the mating piece.

Solution: To ensure mating dowel holes, skip measuring altogether and use dowel centers (³⁄₈ " dowel centers, #42366, 800-279-4441, rockler.com). First, use your jig to drill all the dowel holes in one of the two mating pieces; then slip a dowel center in each hole (as shown below) and clamp the joint together. A dimple left by the dowel center shows you where to drill the mating dowel hole. Locate the doweling jig over the dimple and drill the hole (second photo below).

Problem: I set the jig up correctly, but the, dowels still fit sloppily in the drilled holes.

Solution: Check that the dowels have been made to precisely the rigtht diameter (below). Mass-produced, commercially available dowels may be manufactured slightly over or undersized, and, like most wood, swell or shrink with humidity change. If the dowel size matches, it may be that your jig's guide holes have become worn and imprecise—leading to sloppy dowel holes. Replace any guide hole inserts, or, if the jig doesn't have them, discard the jig.