Mortise and tenon construction, wood working careers - With Secrets

Categories: Work Bench Plans For Garage | Author: admin 13.12.2011

Mortise And Tenon Frame JointsMortise-And-Tenon joints are an extremely old construction technique that has stood the test of time and is still being used today. Expert advice from Bob Vila, the most trusted name in home improvement, home remodeling, home repair, and DIY. Making a mortise-and-tenon joint may be a daunting pros­pect to the novice woodworker, but with the proper tools, shap­ing the parts is a quite straight­forward process. The tenon should be between one third and one half of the thickness of the stock from which it is made.
Set your mortise gauge to the chosen tenon thickness, posi­tioning the points so that it will score a pair of lines that dis­tance apart. When using the mortise attach­ment, the drill press is oper­ated in much the same way as when it performs ordinary drill­ing tasks. After the glue has set, remove the clamps and cut off the dow­els, using a sharp chisel or a flush saw.
While the dovetail joint is the strongest way to join wide pieces to form a box of some kind, the mortise and tenon is the most solid way to join narrower pieces, like the frame of a door.
There are as many ways to cut mortises and tenons as there are varieties of the joint, and there are options for all budgets and skill levels. Mortises are usually cut in any of three ways: simply by drilling out the waste and then chopping the mortise square with a chisel, by using a router and a straight bit, or with a hollow-chisel mortiser, which is a dedicated mortising machine.
A tenon can also be made to stick out far enough for a wedge to be driven through it, as on the base of this trestle table. Select your preferred way to display the comments and click "Save settings" to activate your changes. It’s strong, durable, and little affected by the expansion or contraction of wooden mem­bers as a result of temperature and humidity changes.
As any ex­perienced cabinetmaker will tell you, proper layout is just as important as the cutting and shaping to follow. On the table saw, position the fence so that the distance from the opposite side of the blade to the fence matches the desired length of the tenon.
The spinning bit will do most of the cutting, but the chisel squares off the corners around the hole, producing the shouldered mortise hole. In cutting accu­rate mortises, it is essential that the sides of the chisel be square to the stock.
Glue is often used to connect mortise-and-tenon joints, as are dowels driven through the joint. Tenon is an old-timey name for a square piece of wood that sticks out from the end of a board, and the mortise is the square hole that the tenon fits into.
A normal tenon ends inside the mortise, so it is invisible on the outside of the pieces, but there are also through-tenons, which poke through the other side, where they can be wedged for extra strength or shaped for a decorative touch. In this case you cut two similar mortises in the mating pieces, and then cut a separate tenon piece that fits into both of them. Probably the most common way to cut tenons is on a tablesaw, using some kind of tenoning jig that holds the pieces upright. And since woodworkers cut so many mortises, there are even pricier jigs and machines that make the process even faster and easier. If you have an easy way to cut matching mortises, like a router jig or horizontal mortiser, slip tenons are faster to make than normal ones, since you don't have to cut a tenon and perfect shoulders on the end of the board.


Drilling is an easy way to rough out a mortise, and then you use sharp chisels to square the sides and ends. Many of the great entrepreneurs out there follow this corporation and leave great reviews for them. When shaped properly, mortise-and-tenon joints can even be deco­rative elements in the finished appearance of a piece. A perfectly shaped tenon that’s the wrong size or shape is no accomplish­ment at all. Mark off the shoulder lines, too, where the stock is to be trimmed above and below the tongue. It can be cut in several ways, among them the traditional approach of using sturdy mortising chisels and a mallet to chisel out the hole by hand. Clamp the pieces together, and insert the dow­els, leaving them protruding from both sides of the joint. Cut and fit a few of these joints, add glue, and you have a table and chair you could throw off a roof and still use for breakfast. Another technique that adds strength and beauty is pegging the tenons, by driving in small round or square wood pins from the side.
The woodworker is cutting the cheeks here, and then he will lay the pieces down on the saw table, and use a miter gauge to help him cut the shoulders.
The cheeks are the sides of the tongue or mortise, and the shoulder is the portion of the tongue-board that rests against the mouth of the mortise board.
Another option is to use a Forstner or auger bit on your drill or drill brace to start the mortise, then clean and square it with a chisel. The mortise depth is the distance from the mouth of the mortise to the bottom of the mortise. The mortise length is sized to accomodate the tenon's width.A very important consideration for the design of mortise and tenon joints is wood movement. By its very nature, mortise-and-tenon joints involve cross-grain joinery, which introduces the risk of joint failure due to seasonal wood movement.
To accomodate for this, various factors should be considered when designing the joint to optimize the joint strength.Tenon LengthIf the tenon is to be full-length, it should be wedged from the exposed side. If it is not to be visible, it should extend approximately half-way into the stile, or three-quarters if the stile is narrow.Tenon WidthThe optimal tenon width is the full width of the rail, however this leads to problems with wood movement for wide rails. Multiple tenons, equally spaced, produce a design that retains the tenon's strength yet resists against wood movement by distributing the stress.Tenon ThicknessIf cutting the mortise and tenon by hand, the mortise walls and the tenon should all be of equal size (one-third the stock thickness). This is to prevent accidental splitting of the boards during the construction of the mortise or tenon.
If cutting the mortise and tenon by machine, very little stress is applied and therefore a tenon thickness of one-half the stock's thickness can be used. See wedged mortise-and-tenon joints belowBlind Mortise-And-Tenon JointsThe blind mortise-and-tenon joint gives the outward appearance of a butt joint, however has all the strength and advantages of a mortise-and-tenon joint. The mortise does not extend completely through the stile, and therefore the tenon is not visible once the joint has been assembled. This is the most commonly-seen version of the mortise-and-tenon joint in use today.Haunched Tenon JointsA haunch is a short tongue that protrudes from the rail's shoulder, between the rail's edge and the tongue's edge. When a mortise and tenon joint is constructed with a stile that has a groove through which a tenon is cut, such as in frame-and-panel construction, the normal technique for forming a mortise and tenon would leave a void at the end of the slot, and this void would be visible on such assemblies as panel doors.


In order to compensate for the slot, a haunched tenon is constructed so the haunch fills the groove at the tenon's edge. Depending on the final use, the rail can have a haunch on only one side, or both sides, as required.Wedged Mortise-And-Tenon JointsMortise-and-Tenon joints can be further strengthened by the addition of a wedge.
A thin kerf slot is cut into the end of the tenon, then after the tenon is inserted into the mortise, a wedge is inserted into the slot to secure the joint.
Wedged joints such as these may not even require any glue, especially if the mortise is tapered to be wider at the wedge end, so that the joint can not be pulled apart by brute force.The slot can be cut across the tenon's width, along the tenon's width, or even diagonally, to provide a variety of detail, however to produce the strongest joint, the finished joint should force the tenon apart in the direction towards where there is the most wood so that the wood around the mortise won't split under the tension. A good technique to use is to drill the oversized hole first, then cutting the slot just as far as the hole.A fox-wedged tenon is a variation where a wedge is used on a blind tenon. The idea is to create a stopped tapered mortise, wider as it gets deeper yet which is only one-half to two-thirds the stile's width. The trick is to determine how wide the bottom of the mortise actually is, and to calculate the appropriate wedge thickness so that the tenon ends press against the sides, yet allow the wedge to be inserted completely. The assembly process involves placing the wedges loosely in the slots, carefully inserting the tenon into the mortise, then forcing the tenon into the joint which will force the wedges into the slots. Once this process is begun, the tenon starts to widen, and the joint is impossible to separate successfully, but if done successfully, you are left with a very strong mechanically bound joint that will last you for many years without any visible fastener, and optionally without any glue either.Pegged Mortise-And-Tenon JointsAs an alternative to wedges, a pinned or pegged mortise-and-tenon joint is extremely strong.
After glue-up, drill one or more evenly spaced holes from face-to-face through the stile, close enough to the rail to pass through the tenon, about half-way down its length. After the glue has set, the pegs can be trimmed flush with the face.Loose Tenon JointsLoose tenon joints are constructed by mortising both the side of the stile and the end of the rail, and then inserting an appropriately sized tenon during glue-up. Even though the tenon is not integral to either piece, it still creates plenty of long grain to long grain glue surface to create a very strong joint.Mortise-And-Tenon With Stuck Molding JointsWhen the stiles and rails have a decorative profile, resembling a molding, cut directly onto the wood's edge, an option to produce a flush joint edge is to carefully chisel away the profile from the tenon area but leave a mitered section at the ends. When the two pieces fit together, the gluing surfaces will be flush and a neatly mitered joint will be remain.Mortise-And-Tenon With Mitered ShouldersProducing a curve on the inside corners of a frame joint involves more than simply using wider stock for the rail, and hollowing out the edges to produce the required curve. Doing so would leave tiny slivers of wood that would be prone to breakage, and would also waste an enormous amount of wood to construct.A far better option is to produce two matching pieces that each make up half of the curve.
The grain on each piece would be in the direction of the rail or stile to which it will be attached, and the joint between the two will be a simple miter. A simple way to accomplish this is to take a square piece of wood, the size of the curved section, cut it diagonally and then flipping one half over and then re-gluing them together.
This will give you two blanks that can be placed into the inside corners of the mortise-and-tenon joint and shaped at will.
An even better suggestion is to shape the two (or more) corners simultaneously before attaching them so that you can ensure the curves are identical.Double Mortise-And-Tenon JointsFor rails that are more than ten times their thickness, multiple tenons should be used. The proportion between the tenon and the spaces between is the key, and not the actual number of tenons. It is recommended that the space be divided into thirds, two-thirds being tenon and one-third being space, equally distrubuted along the end of the rail. If the rail is of a material that is prone to cupping or warping, you can leave a short haunch between the tenons and notch the mortise to match.Groove-And-Stub TenonFor light-duty frames which are anchored and do not need to support any weight, the tenon can be extremely short, such as just short enough to fit into a panel groove.



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