If you are jointing two edges, as for a "glue-joint," first examine the pieces to see which edges will best go together, according to the purpose for which they are intended. Look at the end grain so as to arrange it in different ways if you are building up a piece of selected parts (Fig. 559). If merely joining two or more boards to make a wider one, notice the way the grain runs lengthways, and the way it crops up to the surface, for you will have, for everything but the roughest work, to plane the surface over after the joint is glued, and if the grain runs in two or three different ways it will be harder to make the surface smooth. There are cases, however, in handsomely figured wood, as quartered oak or mahogany, where you will arrange the grain in the way that will look the best, but in such cases you expect to go through extra labour for the sake of having the article as handsome as possible. With soft, straight-grained white pine or whitewood, these matters are of less importance. When you have the pieces laid together in the best way, mark on the surface right across the joints (Fig. 552) so that you will know how to put the pieces together, for you will forget how they were arranged after you have moved them around a few times.
Fig. 553.
Joint each edge separately. For nice work it is well to joint the edges of the successive pieces alternately from opposite sides,—that is, if in planing the edge of the first piece the marked (or face) side of the board is towards you, plane the edge of the next piece with the face side of the board against the bench, or away from you. This helps to counteract the result of any tendency to tip the plane to one side or any inaccuracy in setting the plane-iron. See Shooting-board.
Then, putting one piece in the vice with the jointed edge upwards, lay the other edge upon it in the proper position and see if the two edges touch throughout. If not, one or both must be planed with thin, careful strokes until they do fit, for the joint will not be good unless the edges coincide. Remember, however, that it takes more than merely touching to make a good joint. The surfaces of the boards must be in line (in the same plane). Of course this really depends upon the edges being square. Test by holding a straight-edge, the square, the edge of the plane, or anything straight, against the surface of the boards (Fig. 553).[47]
Do not be misled by the directions you may see in "amateur" books and magazine articles which tell you, for cases like this,—when you wish to glue up the lid of a desk, for instance,—to plane and sandpaper your boards carefully on the sides and then fit the edges together, after which you "have only to glue the edges and the job is done." That is not the right way to make a glued joint, as you will find out for yourself after you have planed a few dozen boards the second time. The skilled workman seldom attempts to do this except in repairing or some case where the surface of the pieces must be preserved. The practical work-man's way (which is the way for you), is to glue first and plane afterwards. The best way, practically, is to glue up the rough boards before they have been planed at all, and then have the whole planed down as one piece by machine to the required thickness. Of course you should get the surfaces as nearly in line as you can, to avoid needless planing afterwards, but give your special attention to making the joint hold (see note under Clamps).
Sometimes the edges of boards to be glued are purposely planed, hollowing lengthways, so that the two pieces touch at the ends, but do not quite come together in the middle, the idea being that a clamp at the middle will force the joint together for its whole length and will give a stronger result than to attempt to make both edges exactly straight. If there is to be any open place in the joint before gluing, it is better to have it at the middle than at the ends, but there is a difference of opinion as to whether there is any advantage in springing boards to fit in this way.
Before gluing hardwood edges, it is well to tooth them over with the toothed-plane, if you have one. (See Plane.)
See Plane, Gluing, Joints, Cleating, Dowelling, etc.
Joints and Splices.—There are many kinds of splices and joints used in the different branches of wood-work, a few of which are here given.