Dead-on dowel joints
Using only basic tools and careful layout, you can assemble dowel joints that rival the strength of mortise-and-tenon joinery, and in less than half the time. In fact, dowels beef up nearly any end-to-end, edge-to-face, and mitered joint.
Jigs vary in price and features
Doweling jigs range from a simple but nonadjustable $12 jig to the $310 multiadjustable Dowelmax, photo below. But for less than $60, a self-centering jig with removable drill-guide bushings handles most doweling. You'll also need a brad-point or bullet-point drill bit to match the jig bushings and a countersink wider than the bit.
Although you can buy dowels in 1⁄4 ", 5⁄16 ", 3⁄8 ", 7⁄16 ", and 1⁄2 " diameters, the 1⁄4 " and 3⁄8 " sizes handle most jobs. (See Sources at bottom of page.) Our favorite dowel pins: expandable fluted dowels like those shown in the Shop Tip that allow glue to escape through the flutes but swell to firmly grip the holes. Either 11⁄2 " or 2" lengths will work; but the 11⁄2 " dowels provide ample reinforcement for most joints in 3⁄4 "-thick stock.
Fluted dowels expand to create a solid joint
You could cut your own dowels and score glue-relief grooves in the sides, but you'll save time using commercially available dowels. Like pressed-beech biscuits, the compressed wood in these 3⁄8 " dowels expands about 1⁄32 " on contact with moisture in the glue, as shown below, creating a tight fit.
For a simple butt-joint, first label your parts. To ensure perfectly mating joints, number the joints 1 through 4 on each piece of a four-sided assembly before marking the dowel locations, photo below.
We positioned these marks to center two 3⁄8 " dowels 11⁄4 " apart on 31⁄4 "-wide frame parts. You can add more dowels for increased strength, but avoid spacing them closer than 1⁄4 ". And leave at least 1⁄8 " of wood between the edge of the dowel hole and any surface of the workpiece.
Set the drilling depth
Next set the drilling depth to half the length of your dowels plus 1⁄16 " to allow for trapped glue. At that distance plus the length of the jig bushing, wrap tape around the bit, photo below.
Jig for drilling ends and edges
To drill a dowel hole into the end grain of a workpiece, align a self-centering doweling jig index mark over your marked dowel location, top photo, below. Then drill two dowel holes to the tape at both ends on each rail.
Now repeat the process on the edge of the mating workpiece, middle photo. Moisture in glue can swell the rims of a dowel hole, pushing the pieces apart. To prevent this, bevel the hole edges with a 1⁄16 "-deep countersink, bottom photo.
Then glue and insert dowels into either the stiles or rails. Glue the exposed dowels and joint surfaces, tap the parts together, and clamp the joints for one hour.
To make edge-to-edge joints, use the same technique to mark and drill mating edges. Place holes no closer than 1⁄8 " from the ends to avoid breaking out the end grain while assembling the joint.
Edge-to edge joints
To make edge-to-face joints, start by drilling dowel holes along one edge as described in the previous section. Drill the holes deep enough to make the protruding dowels at least 3⁄16 " shorter than the thickness of the mating piece.
Use dowel centers (see Sources, bottom of page) to transfer dowel-hole positions from the edge of one piece to the face of the mating piece. Depending on the size of your dowel centers, either place them in the dowel holes you just drilled, or insert a dowel in each hole and slip them over these dowels, top photo below.
To mark the face of the second joint part with the dowel locations from the first one, align the ends of both workpieces using a block. Then tap the face of the second part against the dowel centers, middle photo.
Now use a brad-point or Forstner bit in your drill press to drill the mating holes at each location marked by the dowel centers [Photo I]. Set the drill-press depth stop for the length of the protruding dowels plus 1⁄16 ".
Dry-assemble the joint to test for fit; then carefully disassemble it. Then glue and clamp the pieces.
Doweling jigs. 3⁄8
" doweling jig no. 35242, Rockler, 800-279-4441, rockler.com. Self-centering, fixed-bushing jig no. 109-142, Woodworker's Supply, 800-645-9292, woodworker.com. Self-centering doweling jig no. 25K64.01 with interchangeable bushings, Lee Valley Tools, 800-871-8158, leevalley.com. Dowelmax Kit with 3⁄8
" bushings, O.M.S. Tool Co., 877-986-9400, dowelmax.com.
Countersinks. Grizzly set of five countersinks no. G5729, from Amazon.com.
Dowel centers. Each come in packs of 5: 1⁄4 " outside, 3⁄16 6" inside no. 66J45.01; 3⁄8 " outside, 5⁄16 " inside no. 66J45.02; and 1⁄2 " outside, 3⁄8 " inside no. 66J45.03; Lee Valley Tools.
Fluted dowels. 1⁄4 x 11⁄2 ", Rockler #70342.