Build a modern coffee table
This mitred coffee table includes clean lines, storage and a chance to add some interesting, visible joints. It also provides a comfy place to put your feet up after a hard day’s work, if you choose to add a dedicated cushion.
We recently purchased a new sofa, so I anticipated my wife’s next question: “What sort of coffee table are you going to make us?” We wanted something with clean lines and some storage. The option to put your feet up at the end of the day was also a plus.
Flush Them Up
A router with straight bit, equipped with a simple piece of plywood covering about half the router’s footprint, make easy work of flushing up the solid wood edging. The bit is set slightly above the lower surface of the plywood base.
Brown uses stop blocks clamped to his rip fence to position the bottom and top for stopped grooves. He butts the trailing edge against the rear stop block, lowers the workpiece onto the blade, and cuts the 3/16"-deep groove.
Once the rip and sacrificial fences are set up, Brown makes all the passes where bevelled edges are needed. Setting up the fence takes a few minutes but allows the user to cut quick, accurate mitres.
With the outside case parts cut to size and grooved for the back, the back panel can be cut to size and rabbeted. The tricky part is getting the visible gap between the back and case parts even.
Tape, Clamp and Flip
Brown adds masking tape across three of the bevel joints that make up the case, then clamps a few straight pieces of scrap to both sides of the joints and flips the whole assembly over so it can be glued and assembled.
With the glued case pieces, the back and the divider assembled, some tape across the final bevel joint as well as some carefully placed clamps bring the joints together for good.
Quick Taper Jig
Using a piece of scrap plywood for a base, Brown screws some stop blocks and a hold-down device to the scrap. The stop blocks have screws in their sides that can be adjusted to fine-tune the angle at which the workpiece gets cut. The edge of the plywood scrap runs against the rip fence to make the cut.
With some stop blocks secured to his crosscut sled, Brown can secure the workpiece with hold-down clamps and make consistently clean and accurate cuts. Both the legs and aprons can be cut this way, but with two different set-ups.
Brown uses a Domino XL to cut mortises in the aprons and legs. With a bit of practice, this is a fast and accurate way to produce very strong joints.
Angled Glue Blocks
To ensure clamping pressure perpendicular to the glue line, Brown added angled blocks to the outside surface of the legs. The two lines drawn on the face of the legs assists with positioning the block.
Attach the Legs
Using a long strip with an angled block on either end, Brown glues two legs onto an apron at once. Clamping the strip at both ends ensures it stays in place.
Two mortises need to be added to each joint to secure the apron assemblies to the stretchers. Working from the outside in ensures any tearout from the cutter exiting the stock will not be seen.
Grooves for the Wedges
With the loose tenons cut to fit the mortises, they can be drilled and kerfed for the wedges. Ensure the kerf your handsaw leaves isn’t too thin, as thin wedges will break when installed in place of wood the same width as the mortise, and the same thickness as the kerf, then cut the strips about 1-1/2" long and tapered their ends so they would easily fit into the kerfs.
Lots of Loose Tenons
To assemble the base joints, Brown first inserts a dry loose tenon into each joint, then he proceeds to glue the other mating loose tenon in place, followed by another loose tenon to complete that joint. While assembling the base, he keeps the aprons against the stretchers with a pair of clamps. In this photo the dry loose tenon just needs to be removed and glued in place to complete this joint.
I opted for PureBond plywood, by Columbia Forest Products, for this project, as it’s formaldehyde free and is harvested responsibly. I had the 4′ × 8′ sheet ripped in half in-store so it would fit into my vehicle and would be easy to handle once I got it into my shop.
I used solid maple edging to cover the plywood edges. To add some contrast, and to match my existing décor, I chose black walnut for the base.
Start with the plywood top section
I cut the sides and top from one continuous piece so the grain would wrap around the piece. At this point the long blank was still 8′ long, while the other was about 41″ long. I ripped enough 1/4″- thick solid edging to cover the front and back edges of these blanks, then glued them in place using masking tape. When dry I used a 3/4″ straight bit in my router, and a piece of 3/4″ stock that covered about half of the base of my router to help me flush the solid edging to the plywood faces. With the bit set slightly higher than the bottom of the plywood base, I ran the router around the edge, being careful not to tip the bit down into the workpiece. Afterwards I belt sanded the solid edging flush.
I then crosscut one end of the longer blank, cut one of the sides to final height, marked and cut the top to length, then trimmed the final side to length. I made sure to mark the pieces so I could assemble them how they were cut from the sheet. I also cut the bottom to the same length as the top.
Grooves to accept a small spline to secure the divider are next. This was just to position the divider during assembly. I ran a 1/8″-wide × 3/16″-deep groove in the inner faces of the top and bottom. They were both stopped a few inches away from the front and back edges. I did this on a table saw, with a block clamped to the rip fence to start and stop the cut. I positioned the part, with the trailing end on the table saws’ surface, then slowly lowered the workpiece onto the blade and made the cut. A pair of splines were then machined to fit the groove.
If you’d rather cut your bevelled edges a different way, go right ahead and do that now. I prefer this method as there is only one setup, and then I can bevel every edge I need to quickly and accurately. To view the details read my article “Tilting to the Right” for an in-depth description of the process.
Measure between the bevelled edges, on the inside of one of the side panels, to determine the length of the divider. Trim it to length, then run a groove in either end to accept the spline. These grooves are also stopped a few inches from the front and back.
Though you can do away with this part, it does add some strength to the table. A rabbet is machined around the edge of the back, and the resulting tenon fits into a groove on the inner faces of the top, sides and bottom panels. It would have been easier to cut the rabbet on the inner face of the back, though they would have forced me to machine the groove in the top, sides and bottom far too close to their back edges. Instead, the back panel has to be accurately measured and cut, so an even gap appears between the back and the four adjoining panels.
I ran a 1/4″-deep × 3/8″-wide groove in four case pieces, and made sure the inner edge of this groove was located 7/8″ away from the back edge of the parts. This will leave the 3/4″- thick back inset 1/8″ from the solid wood edging. Now I cut the back panel to size and machined the rabbets on the four sides of the back, leaving a small and even gap on all four sides once the case is assembled. At this point I cut the divider to final width, then sanded the interior faces of the case parts as well as the exterior face of the back.
Start by laying the four main case parts face down on a long, flat piece of sheet stock, and butting their mating edges up against each other. Apply strips of masking tape across each of the joints, making sure the tips of each joint are precisely aligned. The tape should be tight enough to pull the joint together during assembly, but not so tight the tape breaks. Dry assembly is the perfect time for practicing.
With three of the four joints taped, flip the parts over, install the back and splines and carefully wrap the parts together. An extra set of hands comes in handy here. Before the parts come together, position the divider and splines. Block planing a small chamfer in the edges of the splines might allow for easier assembly of the divider joints.
With the parts lying inner face up, apply some glue to the bevelled joints, back grooves and splines, then bring the parts together one last time. Apply tape across the final bevelled joint, and use clamps where necessary to bring the case together. Be careful when using clamps on the bevelled edges, as uneven pressure will quickly throw these joints off.
Legs that met the front and back aprons and 90° would be much easier to machine, but I liked the look of the angled legs. I set out to use a fairly standard mortise and tenon on an angle, but realized mitering the leg / apron joints would complement the bevelled case corners much better. Constructing the base a simpler way is the best way to simplify this project.
I had a medium-sized piece of 8/4 black walnut, and was able to source all my parts from it. I dressed the board to about 2″, then cut the four legs, two aprons and two stretchers from the board oversized. In fact, I cut two leg blanks about 10″ long × 5-1/2″ wide, and was later able to obtain two legs from each blank.
Four tapered legs
Because the legs are too short to safely joint, I ensured one edge of each leg was straight, then I marked and band sawed each leg from the blank. The exact taper on the inside edge of the legs isn’t crucial, as long as the legs look pleasing. I then cut the taper on my table saw with a simple shop-made taper jig. The legs were longer than needed, but they would be trimmed to length after they were fixed to their mating apron.
Because the upper section of the legs and the entire length of the apron are different widths, and because we’re not aiming for a 90-degree joint, the mitres have to be carefully measured. I placed the apron on my bench face up, then placed one of the legs on top of the apron at the angle I wanted. I added a mark on the leg, first where the outer face of the leg crossed the upper edge of the apron, then added a second pencil mark where the inner edge of the leg crossed the lower edge of the apron. I connected these two marks to form the line where the legs needed to be cut. A few wood stops screwed to my crosscut sled, with a screw driven into their sides, makes for a solid and adjustable way of positioning each leg while it gets cut to length on an angle. I added at least one hold-down clamp to ensure the pieces wouldn’t move while being cut.
With the legs cut to the proper angle, I placed them back on top of the apron, re-aligned the joint, and then marked where the apron would be cut. The same stop blocks were re-positioned on my crosscut sled and both ends of the two aprons were cut.
Assemble the base
These mitre joints would have a medium amount of strength if glued properly, but I decided to add a pair of Dominos per joint, both for alignment during assembly and joint strength. I positioned them towards the inner portion of the joint, in order to keep them from protruding through the outer edge of the legs. A bit of math, then a pencil line across each mitre joint to assist with positioning my Domino XL, and I was off to the races. I used 12mm-thick × 100mm-long Dominos. The dominos were machined to extend slightly further into the legs, as there was enough material, but even with the mortise depths in the apron reduced, they slightly protruded through the upper face of the apron. Not a big deal, as the case would cover that up.
To apply enough force with clamps while assembling the leg to apron joints, an angled clamping block was glued to the outer side of the legs. The angle was cut so one face of the clamping block would be parallel to the joint line. To provide the other face to clamp against, I cut a piece of 2″ × 1″ stock slightly shorter than the top of the aprons, which could be clamped to the apron during assembly. Two angled blocks were clamped to this strip at the right location, so when the apron/leg assembly was glued, clamping pressure could be applied perpendicular to the joint.
I applied glue to the joints and brought everything together. When dry, I repeated with the other apron / leg assembly. To remove the angled block from the side of the leg, I trimmed it with my Japanese ryoba saw, then hand planed the face smooth.
To secure the two apron / leg assemblies to each other I opted for a through tenon in a contrasting wood to jazz up the look. I dressed the stretchers to final dimensions, marked a centerline where they would mate with the aprons, set the Domino XL to create equally spaced mortises and cut the eight mortises. I always referenced off the top of the apron and stretcher, so the upper surfaces of these pieces would be flush. I also machined the mortises in the apron from the front face, so any tearout where the bit exited the cut would be covered by the stretcher.
Create the loose tenons
I planed maple to final thickness then ripped them to fit the overall width of the mortises. The mortises were 12mm wide, but the closest roundover bit I had was 1/4″ diameter. I rounded the four edges with this bit on my router table. I then cut the loose tenons about 1/4″ longer than needed, used a sanding block to ensure the fit was good, drilled 1/8″-diameter holes where the base of the wedge kerfs would finish, then cut the wedge kerfs in the outer end of the tenons. I created a thin strip
Add the stretchers
To ensure the joints were lined up, I inserted one unglued loose tenon into each of the four joints, then clamped the stretchers between the aprons. I then applied glue to one mortise and tenon, hammered the tenon home and tapped in two walnut wedges. I then removed the unglued tenon from this joint, glued it in place and tapped in the walnut wedges. I repeated this with the other three joints. When dry, I trimmed the tenons and sanded them all flush.
Sand and finish
To secure the case to the base I bored four 1/2″-diameter screw head clearance holes into the underside of the aprons, then drilled four 3/16″ diameter thread clearance holes through the apron so the #10 × 1-1/2″-long screw heads could protrude into the bottom of the case without coming through.
I then sanded the upper case and base, and eased all the edges. I selected Varathane’s Professional Satin Clear Finish in an aerosol can for this table. I’ve used it on many similarly sized projects, and it offers ease of application, no clean up and great protection for higher-use items. It takes a while for each coat to dry, but I just apply a coat at the end of the day. Three coats, sanding between each coat, is usually enough.
After the finish has cured for a few days, I use #0000 steel wool and paste wax to buff the finish smooth and to an even lustre. I applied a peel-and-stick pad to the bottom of each leg to avoid scratching my living room floor, then screwed the base into the case. You can stop right here, and put your new coffee table to use, or you can add a padded pillow to a portion of the table to allow a comfy spot for your feet to rest after a hard day’s work. If you want to go this route, read the article in this issue about how to upholster a simple foot rest that looks great and is super comfortable.