The Never-Fail Sliding Dovetail
If you use dovetails only to build drawers, consider adding the sliding dovetail to your repertoire of joint-making skills. We'll show you how to apply its exceptional strength to concealed drawer-face joints, shelving units, or a specialized connection. You'll learn how to make through sliding dovetails and two variations of stopped sliding dovetails.
To get started, you'll need a router mounted in a table and a standard dovetail bit. You can choose among dovetail bits with cutting diameters from 1⁄4 " up to 3⁄4 ", and with cutting edges angled from 7° to 18°. A steeper angle adds reliability in softwood, and narrow stock calls for a narrow bit. We use a bit with a 1⁄2 " cutting diameter and a 14° angle to make sliding dovetail joints in 3⁄4 " hardwood.
When you need a dovetail groove longer than 6", use a tablesaw or a straight bit in your router to plow a groove down the center of the planned dovetail joint. Make it 1⁄8 " wide and nearly as deep as the dovetail groove will be. This step avoids the problem of sawdust packing tightly into the dovetail groove as you rout it.
1. Through sliding dovetails
A through sliding dovetail extends from one side of the joint to the other, leaving the distinctive dovetail shape visible at both ends of the joint. It's the quickest sliding dovetail joint to make, and adds both visual interest and strength to projects such as display shelving.
To make a typical through dovetail, set the bit to cut a groove 5⁄16 " deep. Adjust the router-table fence so it stops the workpiece to help you cut the groove the desired distance from the end of the workpiece. Make sure the fence sits parallel to the miter-gauge slot by clamping a ruler or piece of scrap to the gauge and checking to see that it contacts the fence along its full length.
Attach a wood auxiliary fence to the miter gauge, and turn on the router. A smooth sliding dovetail depends on a perfectly straight groove, so hold the workpiece firmly down on the table and against both fences. Make the cut as shown in Photo A below, allowing the bit to pass through the auxiliary fence.
If you want to place a matching dovetail at the other end of the workpiece, leave the router-table fence unchanged. Flip the board around with the same side down, butt it against both fences, and rout again. To make dovetails in a pair of stiles for a series of shelves, cut a groove in each stile at one router-table fence setting, then adjust the fence for the next pair of grooves.
Now that you've established the size of the groove, it's time to cut a dovetail tenon that matches precisely. Leave the dovetail bit height unchanged, but adjust your router-table fence.
If you have a split fence, bring the two halves of the fence as close to the bit as possible without contacting it, leaving only the outside portion of the bit exposed. If you have a single-piece fence, attach a sacrificial auxiliary fence to it. Turn on the router, and carefully move the fence forward to recess the bit. See Drawing 1, below, for details, but remember that the proper fence setting depends on the thickness of the workpiece.
With a piece of scrap that's the same thickness as your workpiece, make a trial cut with the aid of a feather board, as shown in Photo B, below. Cut one side of the tenon, flip the workpiece around, and cut the other tenon side. Test this sample in the groove and adjust the fence until the tenon slides into the groove snugly but smoothly. When it does, cut your tenon on the workpiece.
Begin to assemble the joint by spreading a thin coat of yellow glue in the groove. The longer the joint, the more likely you'll need extra pressure to put it together. You can use a dead-blow mallet, but see Photo C, below, for a better way. A well-fitted dovetail joint doesn't require clamping while the glue dries.
2. Stopped dovetails in drawer fronts
Choose a stopped sliding dovetail, visible at only one end, when you want to hide the joint or you can't make a through cut. But a problem arises when you need to cut a stopped dovetail at each end of a workpiece, such as a drawer front. Safety requires you to work from right to left on the router table, but the typical table has only one miter-gauge slot. Here's the solution.
Make your drawer front at least 3⁄16 " over its final width. Then, rip away the top 1" at the tablesaw, as shown in Photo D, below, and remove the saw-blade marks at the jointer. Now, cut a pair of through dovetail grooves. Glue the top piece back in place, as shown in Photo E, following, creating two stopped grooves. Trim the drawer front to final width.
Finally, make dovetail tenons on your drawer sides, trim off one end of each tenon as shown below, and slide them into place.
3. Stopped sliding dovetails
The table lamp, shown below, calls for a sliding dovetail joint with a stopped end. We'll use that project for our example of this joint, but the same principles apply in other projects, such as pedestal tables.
Set your router-table fence to center the dovetail bit on the post. Clamp a stopblock on the outfeed side of the fence 1" from the bit's center. (This will result in a groove roughly 11⁄8 " long.) Now, rout the groove on all four sides of a test piece the same dimensions as the post, as shown in Photo F, below, always holding the workpiece firmly against the fence and the table. When you're satisfied with the test sample, make your cut or cuts in the workpiece. At the end of each cut, switch off the router and wait for the bit to stop before sliding the workpiece back, if your switch is easily accessible. If not, carefully slide the workpiece back, holding it tightly against the fence, while the bit continues to spin.
Leave the bit height unchanged. Now, form a dovetail tenon on a test piece, as described above.
Because the groove is shorter than the width of the shade support, you need to trim the tenon to fit. Me sure and mark the tenon, and then remove the waste with two handsaw cuts, as shown in Photo G, below.
