Long clamps (cabinet-clamps), shown in the accompanying illustrations, are extremely useful in making glued joints and in various clamping operations. Many, of different lengths, are to be found in wood-working shops. Although much work can be accomplished without them, if you can afford a pair or more of medium length, or longer, they will be very useful. Wooden clamps will answer every purpose, although steel ones are better, but more expensive.

To clamp two o r more flat pieces together, as in making a "glue-joint," or in clamping framework, as a door or picture-frame, lay the work across the horses, which should be so placed that their tops will be as nearly level, or in the same plane, as possible, and apply the clamps as shown in Fig. 488, always putting pieces of waste wood between the edges of the work and the clamps. Place the clamps so that either the flat side of the bar or the corner, as shown, will lie against the surface of the work, thus keeping it from bending towards the bar when the screw is tightened. The number of clamps to be used must depend on the size of the work, but there is not usually much danger of an amateur's work being clamped too securely.1

Clamps 512

Fig. 488.

If you have to glue a flexible strip, put a stiff piece outside between it and the clamp to distribute the pressure.

You will often find by sighting across the surface of the work as you tighten the clamps, particularly in the case of door-frames, picture-frames, and the like, that the surface is winding. When this happens, move one or more corners of the work up or down, as the case may be, in the clamps, and thus take out the winding. A little experimenting will show how to do this. In the case of framed work, such as doors or picture-frames, test the angles with the square as soon as the joints are brought to a bearing. If the angles are not right, as will often be the case, move one end of either one or both of the clamps to the right or left, as the case may be, and you can easily change the angle until the square shows it to be right, when the screws can be tightened and the joints should close accurately. In clamping nearly all kinds of "case " work, such as bookcases, cabinets, boxes, and the like, these directions about moving the clamps until the angles are correct and the work free from winding are applicable.

1 You may be told that perfect joints do not require much clamping, but a perfect joint is impossible, and as a practical matter, only the skilled workman or the most accurate machinery can make even a good joint of much length, so great is the difficulty of avoiding little inaccuracies. Besides this, there is always the liability to more or less springing or change of shape on the part of the pieces. The joint which was good when you stopped planing may not be as good by the time the glue has set, particularly if the gluing does not immediately follow the jointing. In addition to this, the pressure from clamping at only one or two points, or at points too far apart, may force the joint to open elsewhere. Do not infer from this that even the beginner should be content with a poor joint, with the idea that it can be squeezed and jammed to a sufficiently good fit by applying muscle to the clamps. Of course this jamming or mashing of the fibres to fit occurs, to a microscopic degree, in even the best joint, and it can sometimes be done to a perceptible extent with soft wood, but to do this intentionally is very unworkmanlike, and the greatest care should be taken to make as good a joint as possible before gluing and applying the clamps. Do not, however, flatter yourself that you can make so accurate a joint that you can afford to neglect proper clamping, unless, in such cases as that shown in Fig. 488, you adopt the old-fashioned way of rubbing the two edges together and then leaving the rest to the glue, but this is not so good a process for the beginner, except with small pieces, such as corner-blocks (see Comer-blocks). See Jointing.

In such cases as that shown in Fig. 488, waste no time in trying to get the surfaces exactly flush with each other at the joint before partially tightening the clamps, lest the, glue become set. Any slight alteration can best then be made by tapping with the hammer near the joint, whenever either piece needs to be raised or lowered, putting a block under the hammer if the dent will not be removed by planing (see Gluing). The clamps can then be screwed tighter.

In such cases as gluing the joints of a box, put stout blocks or cleats over the joints before tightening the clamps (Fig. 489), to distribute the pressure. This applies to all cases of clamping where the pieces to be glued are not heavy enough to resist the change of shape from the pressure of the clamps, and pieces of waste wood are almost always required in any case to prevent bruising of the work.

Clamps 513

Fig. 489.

Clamps 514

Fig. 490.

You can contrive home-made clamps out of any strong pieces of wood of suitable length, by nailing or screwing a block at each end (Fig. 490), when the work can be tightly wedged to a close bearing by driving home the double wedge shown, using, if necessary, one or more blocks, B, when you use the clamp for smaller work than that for which it was made. By keeping such clamps for future use, you will soon have enough to answer very well until you can afford to buy the regular cabinet-clamps.

On the same principle, a simple clamp, derived from the Orient, can be made by boring a series of holes in two stout strips - just as the holes are bored in the sides of a ladder, but nearer together. The work to be glued is laid on one of these strips in the same way as shown in Fig. 490. The other strip is then placed directly above and stout pins put through corresponding holes outside of the work, which can then be wedged against the pins in the way just shown.

Another way, which can be applied to many cases, is to put a stout cord, doubled, around the work, and inserting a stick between the two parts of the string, turn it around until, the doubled cord thus be-coming shortened, the parts of the work are drawn together. This can only be done where there is room to swing the stick around, as, for example, to tighten the rounds of a chair by drawing the legs together (Fig. 491).

You can often apply pressure, when no more convenient means are at hand, by making use of the elasticity of a board or pole. Suppose, for example, you need to press two blocks tightly together, as shown in Fig. 492. Place them on the bench or floor and spring in a board or pole between the top of the upper block and a beam of the floor above, as shown, Of course this board must be a little longer than merely to reach between the two points, as it must be sprung into place bent, when in the effort to straighten itself out again it will cause pressure on the blocks. Pieces should be placed outside the blocks when scarring of the surface is to be avoided. The pressure can be applied in any direction, always supposing that you have something firm to press against.

Clamps 515

Fig. 491.

Clamps 516

Fig. 492.

Pressure can often be obtained by a lever, and many applications of the wedge will suggest themselves in your work. Even if you have a shopful of clamps and hand-screws and vises, these applications of the simple mechanical powers often come into play (see Fig. 390). See also page 71.

Adjustable wood-carver's clamps can be bought for holding pieces in position on the bench, and are useful, but by no means necessary, as common clamps, or various devices, can be used.

The small iron clamps which can be used in place of hand-screws are very useful.

For other suggestions about clamping, see Hand-screws.