Joint (construction)

“ The book rack will be made in Group VII. Some form of the groove joint is to be used, none other.
Here we call attention to the difference between the designer and the shop man in their handling of the problem. The discussion of construction gives the designer an opportunity to display the possibilities of his subject. He enumerates all the joints that may be used with propriety in making such a piece as the bookrack, and the pupils are encouraged to make use of as many varieties as possible. ”

“ They have evinced much ingenuity,’ he says, ‘in attaching the uprights to the flat timbers.’ It is difficult, without the aid of drawings, to understand exactly the peculiarities of this variety of construction, but he says they are secured so as to have all the motion of a double joint, which gives them ease, and comparative security in a seaway. ”

“ The construction is shown clearly in the drawing. It is of no value in constructive work.
No. 33. Splice or scarf joint; used in framing, occasionally; of little value to boys.
No. 34. Tongue and groove joint; used in flooring and for sheathing.
Scores of other joints might be shown, but they are seldom used, and are of no value to amateur mechanics.
[258] XXX
THE USE OF THE GOUGE
"There is one tool you have not learned to use," said Ralph, one day, "and I think that it is about time you tried it."
Fig. 155. The gouge
"What tool is that?" asked Harry. ”

“ And the entire construction exemplifies the compartment principle to perfection; a slight injury may affect but a single joint of one out of several thousand canes, while even a severe fall on sharp rocks seldom injures more than a few score canes, and these in a few joints only. ”

“ This is called the hopper joint and it is fastened with nails or brads.
No. 7. End lap. A joint much used in house framing. [252]
Fig. 154. Joints used in construction
[253]
Fig. 154a. Joints used in construction (continued)
No. 8. Shows the lap joint used for splicing two pieces lengthwise. It needs to be nailed or bolted to prevent pulling apart.
No. 9. A middle lap joint.
No. 10. Dovetail lap or lap dovetail. This form resists pulling apart and is a combination of lap and dovetail joints.
No. 11. Shows a modification of the same, only one side being dovetailed. [254]
Fig. ”

“ The man-made universal joint has a wider range of movement, possesses greater strength, and is more perfect mechanically. A universal joint is a piece of mechanism between two elements, which enables them to be turned, or moved, at any angle relative to each other. ”

“ Any staring or opening of an oblique joint is destructive of the effect of such workmanship, as it is of the strength of the joint which is glued together, and requires absolute contact of the parts to be joined. ”

“ One of the first lessons to learn will be that of making wood joints; for no matter what object is to be made, its construction will require some joiner work. There are, of course, a great variety of joints employed in carpentry, but many of them would be too complicated for the boy carpenter. ”

“ System and power to visualize—that is, to see things in their proper relation to one another in the finished piece—make it possible for men to lay out and cut the members to the most intricate frames of buildings before a single part has been put together. Lay out duplicate parts and duplicate joints as suggested in Chapter VII, Section 62. Where several joints of a similar size and kind are to be fitted, mark the different parts to each joint with the same number or letter as soon as fitted that no other member may be fitted to either of these. Fig. ”

“ There are five corner joints which you should know about and these are (a) the butt, or square joint; (b) the lap, or rebated joint; (c) the mitered corner pieced joint; (d) the common dove-tail box joint, and (e) the regular dove-tail joint, pictures of all of which are shown in Fig. 4.
Now when you can saw a board off straight, plane it true and make a good joint you will have small trouble in making anything in wood that you want to make. ”

“ Joints and Joint-structure.—This is the most universal of all rock-structures, since all hard rocks and many imperfectly consolidated kinds, like clay, are jointed. Joints are cracks or planes of division which are usually approximately vertical and traverse the same mass of rock in several different directions. They are distinguished from stratification planes by being rarely horizontal, and from both stratification and cleavage planes by being actual cracks or fractures, and by dividing the rock into blocks instead of sheets or layers. ”

“ Jointing Beams to Posts and Struts.—The usual methods of forming joints between beams, posts, struts, and braces as used in the construction of gantries, stagings, jetties, bridges, etc., are illustrated by Figs. ”

“ When an opening is to be spanned over by a material construction, which must bear a certain weight without bending enough to injure itself, there are two forms in which this construction can be made, the arch and the chain. Every part of an arch is compressed or pushed by the other parts; every part of a chain is in a state of tension, or is pulled by the other parts. ”

“ The universal joint is much used in cotton-mills, where shafts are carried to a considerable distance from the prime mover, and great advantage is gained by dividing them into convenient lengths, connected by a joint of this kind. ”

“ The joiner’s works are in many cases of a complicated nature, and often require to be executed in an expensive material, therefore joinery requires much skill in that part of geometrical science which 477 treats of the projection and description of lines, surfaces and solids, as well as an intimate knowledge of the structure and nature of wood. ”

“ The carpenter of olden time lost many useful hours in studying how to make the ball-and-socket joint which he bore about with him in his own hips and shoulders; the universal joint, which filled all men with wonder when first discovered, he had in his wrist ”

“ In Group IX, which is the first year high school work, the pupil may be expected to give most of his attention to the principles of simple joinery of board and framed structures with the necessary joints. ”

“ The other form has a level surface and the stone is of the same thickness throughout and worked to a rebate on top and bottom edges. In laying stone roofs the joints are usually lapped over with an upper slab of stone.
Joints in Spires.—Four forms of jointing for the battering stonework of spires are shown in fig. 16. A is a plain horizontal joint. B is a similar joint formed at right angles to the face of the work. This is the most economical form of joint, the stone being cut with its sides square with each other; but if the mortar in the joint decay moisture is allowed to penetrate. ”

“ While the weight or quantity of material in a joint increases with the cube of its through-measured dimensions, its surface only increases with their square—or, otherwise stated, we do not nearly double or treble the surface of a joint of given form when we double or treble its weight; and, vice versa, the less the weight, the greater the surface in proportion to the weight. ”

“ If we consider the individual joints as distinct beings, it is so; and when we reflect upon the power of individuality given to each joint, it makes this conjecture the more probable. We can hardly suppose that an ovum of a tænia, which at its full growth is thirty feet long, and composed of four hundred joints, contained a young tænia composed of this number of pieces; but we have seen young tænia not half a foot long, and not possessed of fifty joints, which still were entire worms. ”

“ The shape of the joint cavity varies greatly, and the different divisions of movable joints depend upon it. It is often assumed that the structure of a joint determines its movement, but there is something to be said for the view that the movements to which a joint is subject determine its shape. ”

“ The joiner executes the more minute parts of the wood-work of edifices, comprehending, among other things, the floors, window-frames, sashes, doors, mantels, &c. Carpentry and joinery, however, are so nearly allied to each other, that they are commonly practised by the same individuals ”

“ When long fingers (with shorter palm) are knotted at the joints we find an extreme love for the minor parts of construction, whether it be in the building of a bridge or the endless tasks pertaining to a kitchen. ”

“ From a constructional point of view Fig. 101 is far and away the best joint that has yet been produced. Unfortunately, however, there is not at the present time any hand tool that will economically produce it, owing probably to the fact that the joint is the subject of a patent. The dovetail tongue tapers slightly throughout its entire length, gripping the joint on the principle of the wedge and squeezing the glue into the pores of the wood. ”

“ As the nature of architectural plans depends upon the properties of the wood, stone, or iron, as they must correspond with the material to be employed (i.e., the span of a roof, the construction of a bridge depend upon the material in shape and weight) , so the nature of the organic material determines to a large extent the shapes assumed in the course of growth. ”

“ In cases in which the lateral rigidity of the floors is depended upon to transfer the horizontal strains to the exterior walls which are framed to resist them, no form of floor construction should be used which is not laterally strong and rigid. ”

“ Formerly, in constructing a large superstructure upon a rubble mound, it was a common practice to build a sea wall and a harbour wall several feet apart, and to fill up the intermediate space between them with rubble, so as economically to form a wide structure on the top of the mound, and provide Construction of the super-structure. ”

“ There are two principal methods of gluing edge-to-edge joints, rubbing and squeezing. In a rubbed joint, the surfaces to be joined should be planed so as to meet thruout exactly. After properly planing [page 173] one edge of each board, keep one board in the vise, jointed edge up, and place its to-be neighbor in position upon it. Then use these four tests for an exact fit. (1) Sight down the end to see that the faces lie in the same plane. ”

“ Fig. 102.—Joint with Single Dovetail Tongue and Groove.
Cabinet-work Joints.—With regard to tongued and grooved joints which apply more particularly to the jointing of cabinet work, Fig. 93 is produced by planes which are specially made for the purpose. One plane makes the tongue and another the groove. The handiest sizes to buy are those which joint 3⁄8 in., 5⁄8 in., and 3⁄4 in. timber, it being usual to dowel or loose-tongue thicker boards. ”

“ The graft in this case is only used as a scaffolding. (Our assumed workers with all their ingenuity are not equal to the task of throwing out cantilevers into the void.) But the planks of the scaffolding become an organic part of the new structure, and when the new material used is foreign, we find the marks of divided purpose in plan and construction. The new bone [51] takes longer to form and the work is not so well done. ”

“ This joint is seldom used in actual practice. The separate parts are given in Fig. 56.
At Fig. 57 are shown two cross rails and an upright halved together. This type of joint is used where three [Pg 24] pieces meet, as is the case in building the framing of a poultry house. The joint is nailed together.
Fig. 59.—Cellarette Partition Joints.
Fig. 58 is the end view of an ordinary workshop trestle, showing the application of dovetailed halving [Pg 25] where the legs have a tendency to strain outwards. The inset sketch of joint shows the housing of the top rail to receive the legs. ”

“ Joints cut right across the bedding, and are often variously combined, one set of joint planes traversing the rock in one direction, and another set or sets intersecting these at various angles. Thus, in many cases the rocks are so divided as easily to separate into more or less irregular fragments of various sizes. Besides these confused joints there are usually other more regular division planes, which intersect the strata in some definite directions, and run parallel to each other, often over a wide area: these are called master-joints. ”

“ In carpentry framing owes its strength mainly to the form and position of its parts, but in joinery the strength of a frame depends to a larger extent upon the strength of the joinings. The importance of fitting the joints together as accurately as possible is therefore obvious. It is very desirable that a joiner shall be a quick workman, but it is still more so that he shall be a good one, and that he should join his materials with firmness and accuracy. ”

“ Having laid these two foundations at this distance from one another, build cross walls between them, uniting the outer and inner foundation, in a comb-like arrangement, set like the teeth of a saw. With this form of construction, the enormous burden of earth will be distributed into small bodies, and will not lie with all its weight in one crushing mass so as to thrust out the substructures. ”

“ Fig. 62.—The Two Pieces of a Halved Joint.
The tools used for making joints of the above class are: planes, the gauge, tenon or other saw, chisels, try square, and in some cases a joiner's bevel to obtain and mark the necessary angles, pencil and marking knife.
Plane up the face side and face edge of the timber, gauge and plane to both thickness and width; mark shoulders with pencil or marking knife; gauge to the thickness of the required halving; saw waste portions away; pare up with chisel to a good fit ”

“ By planning the joint work carefully beforehand, or requiring the pupils to plan their joints according to certain standards as to size, no more than two chisels need be placed at the disposal of each boy and none in the general equipment. ”