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Drill dead-on dowel joints

Drilling into board
3 problems and their solutions guarantee your success with any doweling jig.

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.)

Vertical misalignment

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 right). Do so, and though the holes may not center in the boards' thickness, they will line up.

Drawings showing clamping

Horizontal misalignment

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 right) 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 (bottom photo).

Dove joints on drawing

Metal jig
Slide a brad point bit through the jig and into the dimple. While holding the bit in place, tighten the jig to the workpiece; then drill.

Sloppy fit

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 right). 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.

Crooked dowel hole

Caliper with blue numbers
Before heading to the home center to purchase dowels, tuck a caliper in your pocket. Measure before you purchase to ensure they'll fit.

Drilling into board
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