Which is better, furniture made with hand tools or power tools? That may be an ongoing debate in woodworking circles, but this bookcase, inspired by – and designed to complement – the clean lines of an old Craftsman-style writing desk, finds a perfect balance in the use of both.
Dovetails and mortise-and-tenon joints are techniques that have a well-deserved association with quality work. If you visit museums and look at furniture made over 500 years ago, you won’t be surprised to see dovetails and mortise-and-tenon joints holding things together. Now we have faster, more accurate ways to cut these joints with router jigs, but when making just one set of joints, a combination of hand and power tool techniques can compete head-to-head with the jigs, give greater pride in the finished work and put some of the pleasure of handwork back in the making of things. You will need to invest some time in practice with the saw, but pride in your work will grow along with your level of skill.
When we created a new office space in our home, my wife Jean wanted a bookcase made to match a much-loved Craftsman-period desk that she bought used long before we met. We decided that the bookcase should be the same height as the desk so the top surface of the desk and bookcase would work well together visually. I chose through dovetails and mortise-and-tenon joints as the primary means of construction, not to match any particular features of the desk, but to build in the best available construction techniques. The desk has lasted more than 80 years with excellent care and some minimal repair. The use of dovetails and mortise-and-tenon joints will assure that Jean’s bookcase will last as long as it is cared for and found useful. The simple beauty of hand-cut joints will assure that it will be cared for.
Getting started
Set your marking gauge to very slightly wider than the thickness of the stock being joined as in Fig. 1 to allow for just a bit to be sanded flush after assembly. (An additional 1/32" is usually sufficient.) Use the marking gauge to mark the ends to be joined on both sides (Fig. 2).
I like to double up the end boards to cut both sets of dovetails at the same time. This not only ensures that the left and right sides are perfectly matched, but also allows you to see more clearly that the cuts are being made square to the stock. First, clamp the boards together with the edges aligned and face sides out. Mount them as a pair in a vise, being careful that the ends are level. Measure for the placement of the spaces between the dovetails, and use a square and pencil to mark for the cuts (Fig. 3). I try to keep the size of the space between the dovetails small to minimize the amount of chiseling. Also, small pins are a classic look for hand-cut dovetails, and will never be mistaken for the routed variety, which have to be at least wide enough for the router bit to pass through in making the cut. Using a carpenter’s square, set up a bevel gauge blade angle from the 1/2" mark to the 4" mark on the other leg of the square. This will give a 1:8 ratio, an ideal angle for use with hardwoods (Fig. 4). Mark on both sides of the stock down to the line made by your marking gauge earlier (Fig. 5). The pencil mark on the back side gives some assurance that the cut through the full thickness of both sides hasn’t wandered and doesn’t require additional attention from the chisel prior to marking the pins.
Cutting the dovetails
Use a dozuki saw or backsaw to cut down to the marking gauge line as in Fig. 6, checking both sides to see that the saw has gone to the full depth.
To remove the waste between cut lines, I use a rather quick and aggressive technique. Keeping slightly outside the marking gauge line, chisel down, then at an angle from a slight distance away to remove a chip. The second chisel cut will go deeper, and the third will go at least to the center of the board. Then turn the board over and do the same from the opposite side. On the second or third strike you will feel as the cut loosens the chunk of wood between the cut lines. I use scrap wood under the board to prevent unnecessary chisel cuts into the top of my workbench. At this point, place the chisel in the marking gauge line for final cleanup (Fig. 7). Angle the cut very slightly in towards the center of the stock. The important point in the success of this technique is to keep the preliminary cutting shy of the marking gauge line. If you cut right on the line the chisel can pull into the cut, distorting the marking gauge line and giving a poor fit to the pins. Leaving material at the marking gauge line for final cleanup allows the chiseled marking gauge line to be precise.
Marking the pins
I use a simple technique to hold the dovetailed parts in position for marking the pins. Clamp pieces of wood along the lines scribed on the inside of the bookcase ends. Rest the bookcase top in position on the pieces of wood and use a bar clamp to hold the parts tightly in place. Then, use a marking knife to scribe along the dovetails, transferring their positions onto the ends of the bookcase top as in Fig. 8. Use of the marking knife rather than a pencil is crucial to having a precise line for making a precise cut. Next, use a square and pencil to mark the end grain for an additional guide, and use the gauge to mark the depth of cut lines on both ends, and on the face and back sides.
Cutting the pins
Use the dozuki saw or backsaw to cut along the scribed lines as you did before. After the lines forming the pins are cut, the power-tool aspect of the work comes into play. I use a plunge router to speed up the process by precisely hogging out the large amount of material between the pins. The time saved in chiseling makes this small accommodation to power tools worthwhile. With the router turned off, adjust the fence so that the cutter lines up exactly with the marking gauge line as shown in Fig. 9. I use a 3/8" spiral cutter. Mark start and stop lines to guide your routing, and gradually lower the router into the cut as you move it back and forth between the lines to clear most of the waste. Use a chisel to break out the chunks (Fig. 10), and then chisel into the corners to finish the pins (Fig. 11).
Then check the fit. Rather than force them together at this point, I just inspect them closely to anticipate problems in assembly as in Fig. 12, and then go to work on the mortises and tenons to attach the bottom shelf.
Cutting the mortise-and-tenon joints
I used the plunge router again for roughing out both the mortises and tenons for Jean’s bookcase. Start by marking the tenons on the bottom shelf board and on the bookcase ends. Careful layout at this point is very important. Adjust the fence on the router so that a tongue will remain when the tenons are cut. Adjusting the position of the fence on the router is the hard part and requires first measuring the amount of space between the pins on the top of the bookcase to determine exactly how long the tenons will need to be cut, as this is important in making the bookcase square.
I used a marking gauge to mark the tenon length on each end and both sides of the bottom board, and then adjusted the fence so that the cutter would pass 1/4" shy of the marking gauge line, forming a tongue on the non-tenoned portion of the board. Use the router to remove the stock between the tenons first (Fig. 13). Change to a 1/2"-diameter spiral cutter and rout the mortises from the face sides of the end boards (Fig. 14). You won’t rout all the way through; stop the plunge cut with just less than 1/4" of wood remaining on the underside of the cut. This is to allow for chiseling the mortises square while plenty of backing material is present to keep the mortises from tearing out on the back side of the cut. Use a 1"-wide chisel to begin squaring the mortises (Fig. 15). I align the blade along the cut line and use it as a guide for cutting into the corners. Next use a 1/2" chisel on the ends of the mortises to finish the cut.
Turn the end boards over to rout the insides for the bottom shelf to fit (Fig. 16). Raise the depth of the plunge so that the bit cuts only 1/4" deep, or the depth of the tongue left on the bottom shelf board. Change to a 1" or 11/4" straight router bit to finish forming the tenons on the bottom shelf board. Lower the cutter in increments and check with a dial caliper to adjust the fit to the size of the mortises (Fig. 17). Next use the dozuki to saw the lines forming the tenons as before. Chiseling into the corners of the tenons will be required and using a chisel to cut square into the corner left in routing will come later.
Fitting the center shelf supports
Now that the space between the top and bottom is clearly defined on the bookcase ends, measure the distance between the cutaway space of the dovetails, and the top edge of the mortises. This distance, plus the 13/4" length of the tenons, will be the length to cut the center supports. If your bookcase will be used only for light items, the hardwood shelves could span the full interior length of the bookcase, and the center support could be eliminated. However, I expect this bookcase to carry a heavy load of books, and dividing the span to two 23" sections will not interfere with its usefulness.
Measure and mark the center of the top and bottom boards, then mark lines from front to back 1/4" on each side of center. Then, measuring from the front of the bookcase, mark the tenon locations for routing. After marking the locations for the mortises, put the plunge router in place and trace around the router base to mark for placement of a guide board. Clamp a guide board from front to back on the bookcase top, and using the 1/2" spiral cutter in the plunge router, move back and forth between the lines to cut the mortises in the top (Fig. 18). Next chisel the mortise’s corners square to fit the tenons (Fig. 19). Repeat this operation to cut the mortises in the bottom shelf.
Routing for the back to fit
Use a 1/4" straight bit in the plunge router to rout the two sides and top for the 1/4" oak-veneer plywood to fit (Fig. 20). By routing on three sides and using screws to secure the bottom, the plywood can be removed if repair is ever required, and being securely housed in a dado will prevent what happens to many bookcases where books pushed against the back of the case may push nails out and loosen the back panel.
Cutting the tenons
Next, cut the tenons on the ends of the center shelf supports. Use a sled on the table saw to cut around the perimeter of the tenons. Use a stop block to control the position of the cut (Fig. 21). Then finish forming the tenons using a tenoning jig on the table saw as in Fig. 22. Keep the same side against the jig for both cuts forming the thickness of the tenon, by widening the distance between the jig and the blade to cut the opposite side. This will ensure the best possible fit of all four tenons. In cutting the tenon to final dimension, you can avoid having large chunks thrown back by cutting only partway through, leaving the piece still attached so it can be removed by hand (Fig. 23).
Fitting the base trim
I put a base trim in the front of the bookcase for two reasons. First, the trim teams up with the back panel, mortise-and-tenon joints and dovetails to keep the bookcase from racking under weight, holding the sides and top and bottom shelf perfectly square at all times. Second, it helps bear the load of the center supports. Rout the ends of the bookcase with a 1/4" straight bit (Fig. 24). Then use the table saw to cut a matching slot in the ends of the base trim, using the tenoning jig to hold the board vertical through the cut as before. A snug fit with glue will help to hold the sides and top and bottom square (Fig. 25).
Drilling for the shelf supports
To make certain that all the holes for shelf supports are perfectly aligned, carefully mark the locations on the sides and center supports. Using the drill press prevents drilling too deep, while a reference line on the drill-press fence gives a point of alignment. Drill the bookcase sides as in Fig. 26, then the holes in the center supports.
Routing and last details
To prepare for assembly, use a chisel to remove the last bit remaining in forming the tenon on the bottom shelf (Fig. 27), then cut the bottom shelf as shown in the drawing to only partially overlap the bookcase ends and align with the base molding (Fig. 28). Cut the shelves to length and add the edge trim pieces to the front edge so they half overlap the center supports as shown in the drawing on page 18. Glue and clamp the edge trim till dry, then use a 45-degree bit to chamfer the edges on the upper and bottom shelves and on the outsides of the bookcase ends.
Sand all the parts prior to assembly. I begin with 150-grit paper in a random orbit sander and work through intermediate grits, finishing with 320-grit.
Inevitably you’ll have some fine fitting to do with the dovetails and mortise-and-tenon joints, so do a trial assembly of each joint to make certain they’ll go together without requiring force. Slightly chamfer the ends of each tenon prior to assembly. This will help them to slide into a perfect fit and simplify the assembly process.
First fit the center supports in place between the top and bottom, then apply glue to the pins and tenons and tap the ends in place as in Fig. 29. Next, apply glue in the dado at the ends of the base trim and slide it into place. If your dovetails and tenons fit well, clamping won’t be required. Measure from corner to corner across the front and back to be certain the bookcase is square. If the measurements aren’t exact, the bookcase can be racked slightly one way or the other to adjust it for square. Do this now, however, because it won’t be possible once the glue has dried.
Add the base trim, putting a small amount of glue in the mortise before assembly, and a small bead of glue along the edge where the base meets the bottom shelf. Clamp in place (Fig. 30). Note that some preliminary routing was done before assembly and that the tenons were shaped slightly on the corners (Fig. 31). These operations would be more difficult to accomplish on the assembled piece. After the glue has dried, the dovetails can be sanded down flush with the top and sides. Final sand up to 240-grit sandpaper to prepare for staining.
Staining and finishing
My wife’s request that the bookcase match the color of the desk was a challenge to meet. Normally, I prefer to use woods in their natural colors and thereby avoid the complications involved in finding an exact combination of stains and finishes to achieve a perfect color tone.
Finishing is as much an art in woodworking as cutting dovetails. Stains have different effects on different woods, and what you end up with most often has very little resemblance to chip charts or samples at the store. It’s best to approach finishing systematically, by preparing a wood sample and applying various stains and finishes before taking chances you might later regret. I keep a small collection of wood stains left over from previous projects that provide a palette of colors to work from. The best match was Minwax red mahogany stain finished with two coats of amber shellac, the fourth sample from the left in Fig. 32. That red mahogany stain on oak would be part of the mix surprised me, as it wasn’t my first guess. Sometimes finishing is an art, sometimes a science, and sometimes just dumb luck, but it is always an adventure. Without the test piece to reassure me, staining first in red mahogany would seem a very risky thing.
Leave the back panel off until finishing is complete to get better access to all the surfaces. Sand, finish and attach the back panel after all other steps are done.
Jean’s bookcase is the perfect complement to her Craftsman-period desk, and the small amount of extra time spent on the dovetails and mortise-and-tenon joints will pay off in many years of service and beauty.
Doug Stowe
A 30-year maker of furniture and wooden boxes, Doug Stowe teaches at the Clear Spring School, Arrowmont, Marc Adams School and the Eureka Springs School of the Arts. His most recent book is “The Complete Illustrated Guide to Box Making.”
