Fit should be snug along the 4 Ways to wide cheeks Width = no more than 1⁄3 thickness Make a Mortise of mortised piece Length = at least half the width of By Robert W. Lang the tenoned piece A hole is just a hole, no matter how you dig it.

The deeper the Leave adequate mortise the space between stronger the joint end of mortise & he mortise-and-tenon joint is end of board fundamental in woodwork- Space at ends & ing. Along with the dovetail, bottom is acceptable this joint has been used for Mortise Size Mortise-&-Tenon Cross section Tthousands of years. If you judge by the number of devices and methods devel- oped to avoid making mortises, you thirds the width of the mortised piece Layout Rules might think it difficult and demanding. is a reasonable target. Whatever method you use to make In truth, a mortise is just a hole. That leaves the length of the mor- your mortises, getting them the right As with most holes, it doesn’t really tise, or the width of the tenon to be size and in the right spot is critical. matter how you dig it. The fundamental determined. The tenon will be strongest With machine methods, it is easy to elements are the same whether you chop the closer it is to the size of the piece set where the mortise lies in the thick- by hand or mill with a machine; confu- on which it is made. Make the tenon ness, and generally the width of the sion arises because it isn’t always obvi- as wide and thick as possible, and at mortise matches the width of your , ous what is important to make a sound least half as wide as the overall width be it a bit, bit or a . joint in a reasonable amount of time. of the workpiece. Depth is also an easy target, especially A mortise isn’t any good without a if your aim is a bit deeper than the tenon matching tenon. If the joint fails it is What’s Important, What’s Not length. usually because too little is left There are five surfaces in a typical mor- Unless you are setting up for a large around the mortise, so it makes sense to tise. Two of them need to fit just right production run, it will likely take less Twofer. Ganging parts for layout ensures that let the location and size of the mortise for the joint to work. The other three time to mark all your mortises and work joint locations will be identical, and it saves time. A knife marks a more definite line than determine the size of the tenon. don’t much matter. to your lines. If you accept that the ends a pencil. The first thing to consider is where If you try to make a mortise with a don’t need to be perfect, you don’t need to locate the mortise – too close to the perfect bottom and ends you’re wasting to spend precious time setting stops. end of a board leaves weak grain that time, and asking for trouble. Worry in- Getting close by eye will be faster. can easily break while making the stead about the wide cheeks and make If at all possible, gang parts together mortise, or when the finished joint is sure they are straight and square, but and mark them as a group. Prepare a stressed. don’t bother to make them perfectly story stick and you need only to mea- The width and depth of the mortise smooth. Extra space beyond the end sure once. Knife lines and marking- are equally important. When planning of the tenon doesn’t compromise joint lines might take a little longer a joint, take no more than one-third strength and it leaves room for excess to make, but the payoff is in cutting the thickness of the mortised piece, glue and bits of debris. the finished edges before you start to and make the mortise as deep as you Unless you are making a through- excavate and in providing a path for can. The strength of the joint is mainly mortise, extra space at the ends will your to follow. a function of how far into the mortised let you adjust the position of the piece piece the tenon goes. and easily take it apart after a test fit. The Mighty Chisel Through-mortise-and-tenon joints A good joint can be pushed together In recent years it has become fashion- Wheel simple. A defines the are the strongest, but if you can’t (or by hand pressure and stay together able to write about and demonstrate finished edges of the mortises and is faster choose not to) go clear through, two- when you lift it by the tenoned piece. chopping mortises entirely by hand. and more accurate than repeated measuring.

44 ■ popular magazine February 2014 Lead Photo by al parrish; step photos & Illustrations by the author popularwoodworking.com ■ 45 It’s a good skill to have, and mortise “Handiwork is no better than depth. When the bulk of the waste pedient and reliable technique. Most are great for squaring up the machinery if the thing produced is removed, drive the chisel straight of what you read, however, makes the ends of machine-made mortises. But be needless and without meaning, down at the ends. If you can keep the operation far more complicated than in the end you’re digging a hole and no and the principle to be estab- chisel from leaning side-to-side, that’s it needs to be. matter how skilled you might be and lished appears to me to be, not all there is to it. With a plunge router equipped with how nice your shovel is, you’re still the supremacy of the hand over The mass of the chisel helps keep it a and an spiral-upcut bit, you have digging a hole by hand. the machine, but the supremacy of plumb, if you have a loose grip when what you need and can get to work. There are two steps to making a mor- the thing that is needed over that you place it. If the business end of the Remember that the ends of a mortise tise – removing the waste and tidying which is made more or less as a chisel is square, that is another aid to do not need to be pretty and they do up the edges. The mass of a mortise pastime.” keeping it vertical. And if you position not need to be precisely located. What chisel helps considerably, and if the —Gustav Stickley (1858-1942), yourself behind the chisel, you will be does need to be precise is the width (the wood is soft and agreeable, you can Icon of the Arts & Crafts movement able to see if it is leaning left or right. diameter of the bit) and the location hand-chop a mortise in a short amount You can tell when the chisel has been Use a fence. At the drill press the fence Overlap. The Forstner bit is guided by its (that is controlled by the fence). It is of time. If the wood is hard, or the mor- driven to an optimal depth by the sound provides for consistent placement of the edges and won’t wander off course when generally easier to bring the router to tises many, you’ll find yourself in the of the with each cut to create a and by the amount of resistance you Forstner bit. Drill a series of holes with a space removing the waste between the first set of the work so you can see what you are in between. holes. position of your ancestors – wishing V-shaped recess. Placing the chisel to feel. Pry against the bevel to gain lever- doing than it is to plunge the work onto for a more expedient way. start the cut requires some finesse, so age and the back and end scrapes the the bit at the router table. After the joint location, this method takes a while. sides as you remove the waste. If you can keep from tipping the there are two general methods for using The other method is to start near If you don’t own a mortise chisel, router or biting off more than the router the chisel to chop out the mortise. The an end and make a series of cuts in you can still make a mortise by hand, can chew, all you have to worry about first is to make a cut in the middle area one direction, then lever out the chips but you need a lot more patience. The is keeping the fence tight to the work. I of the space and reverse the direction and repeat until you reach the desired process is essentially the same: Make a usually plunge the bit to the final depth series of vertical cuts then lever out the at each end, setting the location by eye. waste. A standard chisel doesn’t have Then I waste the material in between the mass to go as deep with each cut. with successive passes that increase in depth. No Shame in Using a Drill There are limits to what the router If you look back in old books about can comfortably do. Mortises 1⁄4" wide woodworking technique, the use of a In the . Incisions from a marking gauge Cleanup time. It takes several cuts to square and 1" or so in depth can be made with drill begins to be recommended right provide a place to locate the end of a wide off the end with a conventional chisel. Posi- a small router. Beyond that it becomes about the time that efficient drill bits chisel. When the chisel is in place, little effort tion an appropriately sized mortise chisel in a time for the big-boy router that can be became readily available. Again, the is needed to shave off the high spots left by knife line and you can do it with one cut. harder to control. the drill bit. method you choose depends on the wood you are working with, the num- On your mark. Set the tool to the ber of mortises you need to make and would have with a stationary machine, layout line and avoid the need 1 1 your desire to get the job done. use a bit that is ⁄16"- ⁄8" smaller than the to measure more than one time. Size does matter. The mass of a mortise chisel Dig deeper. After the first cut, chips and parts together to provide a enables it to drive deeper and remove more debris fall into the previous cut, allowing the If your mission is to avoid the spouse width of the mortise. As with the chisel, stable platform for the router. wood than a standard chisel. chisel to go deeper with the same motive and kids, get out your brace and bit and the important thing is to keep the bit force. drill a hole to the depth of the mortise plumb side-to-side, and you can easily at one or both ends. That reduces the see that from the end of the mortise. need for chopping. If you want to be After you need to pare the productive, the more wood you can side walls with as wide a chisel as you remove by drilling the better – if you can. If you marked the edges with a have an efficient and reliable way to gauge or a knife, you will have a defined power the drill. channel to locate the chisel. Paring is A drill press, equipped with a fence easier than you might think, especially Hole strategy. Make a full-depth and a Forstner bit, is ideal. You can if you excavated the holes with a drill plunge at each end of the mortise, use a bit the exact size of the intended press; all you need to do is shave off locating the cutter to the layout mortise, overlap the holes and be con- the high spots. lines. Then make a series of fident that the holes are vertical. This progressively deeper passes in between. reduces the chisel work to easy paring Router & Fence on the side walls and perhaps a couple In theory, the electric router is the ideal of cuts on the ends. tool for making mortises. In reality, it Leverage. The intersection of the bevel and At the end. After removing the bulk of the the back is an effective fulcrum for levering waste, chop straight down at the ends. It’s OK If you don’t have a drill press, use a is only if you can wade through the out the waste. The sharp, square end scrapes if the end cuts are not perfect. hand-held drill with a brad-point bit. dozens of jigs and complex methods the edges clean on the way out. Because you won’t have the control you that are available and arrive at an ex-

46 ■ popular woodworking magazine February 2014 popularwoodworking.com ■ 47 Down low. Clearance between the auger bit First in. The drill bit does most of the work One way out. Chips are pulled up by the bit and hollow chisel is essential for the tooling to and leads the way for the chisel to cut the and exit through the slot in the chisel. Insert operate efficiently. Don’t worry about leaving straight surfaces. the chisel so the slot is facing forward; if it’s a ragged bottom. sideways, the hole will fill up with chips.

The spiral bit pulls the material out An inexpensive machine might Adjust the Tenon of the mortise as you go. A straight bit breeze through 5⁄16" or 3⁄8" mortises Mortises are straightforward to make, can grind up the wood, but the chips but give up when you increase the size. and if you don’t get caught up in the and chunks have nowhere to go. You can make mortises larger than the minutiae of making them perfect at the Routers are also effective for chisel set by making multiple passes. ends or bottom, they don’t take long to through-mortises in the sides of cases. At the other end of the spectrum, 1⁄4" create. Adjusting the size of a completed It’s easy to put together a to guide hollow chisels and bits can be fragile. mortise is another story – you’re try- the bearing on a flush-trim bit and get There isn’t much metal – you can’t lean ing to make fine adjustments inside a precise walls that are square to the sur- on a gardener’s trowel the way you can narrow hole. face. Drill a hole to get the bit started on a spade. The good part of this is that Tenons, on the other hand, are much (and to remove some of the waste) then in most cases you don’t need to buy a easier to tweak – mainly because you square the corners after routing. complete set of bits. can see what you are doing and have The chisel/bit combination removes access to the work. If your skills in mor- Dedicated the waste and cuts the mortise sides tising make the size unpredictable, wait It’s easy to think that a single machine cleanly in one step. Most chisels benefit and cut your tenons to fit. Err on the will solve all your problems, at least for from a bit of sharpening. Make the out- size of a slightly big tenon then adjust a specific task. A hollow-chisel mortiser side smoother and touch up the inside it until you get a decent fit. PWM is an efficient method for making mor- with a diamond cone. Honing to fine tises, but the cost of this one-trick pony, grits makes the outside look nice, but Bob is executive editor of Popular Woodworking in both dollars and in space, can out- doesn’t add much benefit. Magazine and the author of “Shop Drawings for Craftsman ,” among other books. weigh its usefulness unless you make a As the bit chews up the wood inside lot of mortises on a regular basis. the mortise, the chips must move up A benchtop machine, as discussed through the chisel to escape. Leave in “Woodworking Essentials” in the enough of a gap to provide room and Online Extras November 2013 issue (#207), will do give the bit a head start on the chisel. If For links to all online extras, go to: the job, but not much faster than using a the machine makes a chattering noise ■ popularwoodworking.com/feb14 drill press and a Forstner bit. A machine or starts to burn, the bit is set too close; Video: Watch a mortise being chopped with a moveable table costs consider- it’s choking off the escape route for the under glass in this video filmed at our Woodworking in America Conference. ably more. The benefit is a quantum waste. leap in productivity if you’re willing The best practice for making mor- Blog: Read about sizing tenons to the mor- tise without measuring. to pay the price. tises with a hollow-chisel machine is The performance of hollow-chisel to make a series of square holes with a In Our Store: “Classic Arts & Crafts Furni- ture,” projects built for Popular Woodwork- mortisers suffers as the size of the bit space in between. After defining both ing Magazine by Robert W. Lang. and chisel increase. You can fit a1 ⁄2" ends of the mortise, come back through To Buy: “Mortise & Tenon: Tools and Tech- 5 or ⁄8" chisel in a benchtop machine, and remove the material that remains. niques from a Master Woodworker.” but a 1⁄2" square contains four times Both the chisel and the bit follow the Our products are available online at: 1⁄ 5⁄ the material as a 4" square and a 8" path of least resistance and bend into ■ ShopWoodworking.com square has more than six times the area. an open space next to the cut.

48 ■ popular woodworking magazine February 2014