A glued joint, properly done, will be stronger than the surrounding wood and has the advantage of showing no fasteners. Hot glue has the greatest strength and is used by professional cabinet makers, but it must be handled with great speed and accuracy as it will not adhere after it has cooled. The cold glues are not quite as strong, but are easier for the beginner to use as they set slowly and allow time to adjust the work.
The best hot glues are made of hides and come in sheets or strips. They must be broken into a glue pot which may be one of the electric kind sold commercially, an ordinary double boiler or a can set in a pan of water. The glue is barely covered with cold water, allowed to stand overnight, then heated to a temperature of about 130° until dissolved. The surfaces to be joined must be absolutely dry and clean before the glue is brushed on.
There are several kinds of good cold glues such as casein, resin, and fish glues. These are all satisfactory and should be mixed according to the manufacturer's instructions. All glued joints must be held together firmly with clamps or other devices until the glue has set. Some of the most useful types which can be purchased are illustrated (fig. 85). It is also possible to hold work in place by various systems of wedges and stops (fig. 86). The stops are nailed to any flat surface, the glued work is set in place between them and the wedges driven in until the joint is tight. Certain types of work may be held together by ropes which are tightened by twisting them in the manner of a tourniquet.
In addition to the above, the well equipped workshop should also contain pliers, a spoke shave, a cabinet scraper and an oil stone for sharpening tools. The spoke shave is like a miniature plane and is used in smoothing curved surfaces. The type with a straight bottom is recommended for general work (fig. 87). The cabinet scraper is also like a miniature plane, and is designed for use on flat surfaces where very fine shavings are to be raised (fig. 88). It is invaluable in scraping off paint or in smoothing a surface where further use of a plane might remove too much wood. Both the spoke shave and cabinet scraper are pushed away from the operator.
While it is not within the scope of this chapter to give instruction in the use of power tools, the following motor driven machines are recommended as basic ones for the large workshop. These are the l>ench circular saw, the jig saw, the drill press, the lathe and the grinder. A band saw, planer, machine sander, and dovetailing jig may be added at intervals. In most cases, the manufacturers provide manuals which serve as guides to the operation and maintenance of these machines.
With a knowledge of tools and their use, you are now ready to learn the joints which are commonly employed in putting together all types of pieces (fig. 89). Each has its special uses, though many of them can be applied to a wide range of objects. In planning the construction of any article it is necessary to determine in advance the type of joints you plan to use. It is also advisable to make at least a rough working drawing of the article with all dimensions indicated on it.
Figure 85. Clamps used to hold glued joints together.
The butt joint is one of the simplest and most common of all wood joints, particularly useful to beginners inasmuch as it does not require a high degree of skill. The securing element may be nails, screws, or combinations of either one with glue, dowel-and-glue, or corrugated fasteners.
The blocked joint is a modification of the butt joint; the blocking, either square or triangular, may be glued, nailed, or screwed to the members, depending on the specific requirements of the job. Its advantages are the ease and speed with which it can be made and the ease with which the piece can be disassembled if screws are used in the assembly.
The blind dowel is a variant of the butt joint; it has good holding power and is not very difficult to make but calls for somewhat more accuracy than the through-dowel since the holes must be drilled exactly opposite each other and perpendicularly. This joint can be used where it is desired not to have the dowel show on the surface.
The through-dowel, another variant of the butt joint, is one of the most useful because it is fairly easy, requires little time, and has good holding power. It is much easier and quicker (by hand) than is the mortise-and-tenon and can be used in types of work in which there is no objection to the end of the dowel showing. The through-dowel is made by clamping together the two pieces in correct position and drilling through one piece and into the other. The dowels are then inserted with sufficient glue and cut off with a back saw above the surface, leaving just enough material to sand down flush. The through-dowel is particularly advantageous in some kinds of large pieces if a portable electrical drill is available; the joint can then be made almost as rapidly as a nailed or screwed joint.
The dovetail is one of the most valuable of all joints because of its unusual strength. In addition to the holding power of glue this joint has an advantage over most others in that its form alone gives it great strength. Against it is the disadvantage that it requires very accurate workmanship if it is to be made by hand. There are. however, dovetail jigs which make it fairly easy when power equipment is available.
The mitre joint has many variants of which a few are shown here. It is commonly used where symmetry of appearance is desired, and to avoid the showing of the end grain of one of the members. This joint requires somewhat more skill, unless an accurately set mitre-box is available.
The lock-corner joint is extremely valuable for its great strength, which derives from the large amount of glue area its many open tongue-and-grooves provide. It calls for a fairly accurate skill if made by hand but is quite easy if the bench circular saw is available. This joint is especially useful for corners of boxes and similar places and offers effective decorative possibilities as well.
The half lap is useful in joining lengths of pieces together, having many other uses as well. As with other types of joints, the half lap is frequently reinforced with dowels, nails, or screws in addition to glue.