Woodwork Joints Part 1

Woodwork Joints.

by William Fairham.

EDITORIAL FOREWORD

To be successful in woodwork construction the possession of two secrets is essential--to know the right joint to use, and to know how to make that joint in the right way. The woodwork structure or the piece of cabinet-work that endures is the one on which skilful hands have combined to carry out what the constructive mind planned. And it is just here that the present Volume will help, not alone the beginner who wishes preliminary instruction, but also the expert who desires guidance over ground hitherto unexplored by him.

In the preparation of this new edition the Publishers have secured the services of Mr. William Fairham, by whom the chapters have been carefully revised and re-ill.u.s.trated. Although intended for the practical man, and not professing to be a graded course of "educational woodwork," the Volume is one which Handicraft Instructors will find of the greatest value in conducting woodwork cla.s.ses. No book hitherto published contains such a variety of ill.u.s.trations of joints, almost all of which will form suitable exercises of practical educational importance in a woodworking course.

J. C. S. B.

THE GLUED JOINT

The glued joint in its various forms is in use in every country in the world, and is frequently met with in mummy cases and other examples of ancient woodwork. Alternative names under which it is known are the b.u.t.t joint, the rubbed joint, the slipped joint, whilst in certain localities it is known as the slaped (p.r.o.nounced _slayped_) joint.

[Ill.u.s.tration: Fig. 1.--Simplest Form of Glued or Rubbed Joint.]

The glued joint is made by planing two pieces of timber so that when placed together they are in contact with each other at every point; they are then usually united with glue. Fig. 1 shows a sketch of a b.u.t.t joint in its simplest form. In Fig. 2 is indicated the method of holding the joint whilst being glued; the upright portion is held rigid in the bench vice, thus leaving the left hand to hold the piece which is to be jointed, whilst the right hand operates the glue brush. The pieces of wood which form a b.u.t.t joint may be glued together with or without the aid of cramps or artificial pressure. If the joint is to be made without cramping, the two surfaces of the timber are warmed so as not to chill the glue. The surfaces are then glued and put together and rubbed backwards and forwards so as to get rid of the superfluous glue. They are then put aside to dry.

GLUEING.--The better the glue penetrates into the pores of the wood, the stronger the joint will be; for this reason timber of the loose-fibred variety, such as pine, etc., will hold up at the joint better than hardwoods like teak and rosewood. The glue used for jointing should be neither too thick nor too thin; the consistency of cream will be found suitable for most purposes. It should be nice and hot, and be rapidly spread over the surface of the wood.

[Ill.u.s.tration: Fig. 2.--How the Wood is held whilst Glueing.]

If light-coloured woods, such as pine, satinwood, sycamore, etc., have to be jointed, a little flake white should be procured and mixed into the liquid glue. This will prevent the glue showing a thin black line on the joint.

Broad surfaces of close-grained hardwood having a s.h.i.+ny surface are usually carefully roughened with a fine toothing plane blade previous to glueing.

SUPPORTING THE JOINT.--The jointed boards should not be reared up against a "bench leg" or wall without having any support in the centre, as dotted line at Fig. 5, because in all probability they will fracture before the glue has time to set; and, when we go to take them up to renew working operations, we shall be annoyed to find that they have a.s.sumed a position similar to that at Fig. 5 (shown exaggerated), and this will, of course, necessitate re-jointing.

[Ill.u.s.tration: Fig. 3.--Correct Jointing.]

[Ill.u.s.tration: Fig. 4.--Faulty Jointing.]

[Ill.u.s.tration: Fig. 5.--Boards unsupported.]

[Ill.u.s.tration: Fig. 6.--Boards supported.]

[Ill.u.s.tration: Fig. 7.--(A) Glued Slip, (B) Glued Moulding.]

[Ill.u.s.tration: Fig. 8.--Grain alternating.]

A correct method to adopt is seen at Fig. 6. Here we have supported the joint by rearing up against the wall a couple of pieces of batten, one at each end of the board, thus supporting it throughout its entire width until the glue is thoroughly set. The two or more pieces of timber in a b.u.t.t joint adhere by crystallisation of the glue and atmospheric pressure. A well-fitted joint made with good quality glue is so strong that, when boards of 3 feet and upwards are jointed together by this method, the timber in most cases will break with the grain sooner than part at the joint.

b.u.t.t joints may be cramped up, if desired, and it is customary to warm them as previously stated. In the absence of the usual iron cramp, the amateur may make an excellent wooden arrangement out of any odd pieces of timber that happen to be handy. Two blocks of hardwood are screwed on the base board at a suitable distance for the work in hand; the boards to be jointed are glued and placed in position between the blocks; and the two hardwood wedges are inserted and hammered in opposite directions to each other, thus exerting the desired pressure. An example of this method of cramping is shown in Fig. 25, which also indicates the use of iron "dogs."

When jointing, care should be taken to first plane up the boards true on one side--_i.e._, take them out of winding. The method of testing for this is shown at Fig. 9, and it may with advantage be used when jointing the edges of the boards. Two laths or strips of wood are planed up to exactly the same width, having their edges straight and parallel. One edge of each lath may, if desired, be bevelled a little. The method of using these "twist sticks" or "winding laths" is to put them on the board as indicated, and sight along their top edges. The winding laths, being much longer than the width of the board, show up the irregularity greatly p.r.o.nounced.

THE TOOLS generally used for making the b.u.t.t joints are:--

The jack plane, for roughing the edges, etc.

The wooden trying plane (or iron jointing plane) for trueing up the work.

The try square for testing purposes.

The winding laths and straight edge.

THE METHOD OF WORK is as follows: Each board is in turn put in the vice and planed straight lengthwise; it is then tested with winding laths and a try square (the latter method is shown at Fig. 22).

[Ill.u.s.tration: Fig. 9.--Testing Surface with Winding Laths.]

The boards are then put on the top of one another as at Fig. 1 and tested with a straight edge; they should appear true as shown at Fig. 3; if they show faulty as at Fig. 4 the joints must be again fitted until the required degree of accuracy is obtained. Difficulties may be avoided by care in selecting timber suitable for jointing, and it must be remembered that timber shrinks circ.u.mferentially (the heart side becoming curved) as dotted lines in Fig. 10. If the timber be jointed with all the heart side one way as at Fig. 10, the tendency will be for it to cast as shown by the dotted line. If the timber be alternated as at Fig. 11, the tendency will be to cast wavy, whereas if quartered timber can be obtained it will stand practically straight as the tendency to shrink is in thickness only. The grain of quartered timber is shown in Fig. 12.

[Ill.u.s.tration: Fig. 10.--Showing Heart side of Timber one way.]

[Ill.u.s.tration: Fig. 11.--Heart side of Timber shown alternated.]

[Ill.u.s.tration: Fig. 12.--Grain of Quartered Timber.]

[Ill.u.s.tration: Fig. 13.--Boards showing uniformity of Grain.]

Judgment should also be exercised to avoid jointing in which one piece of timber is wild and large in the grain, and the adjoining piece of a mild-grained nature. Jointed boards should always be glued up with the grain running in the same direction if possible; this we show at Fig. 13, and nothing looks worse than a dressing chest end or similar piece of work in which the grain runs haphazard. When jointing thin timber (say, 1/4-in., 3/8-in., 1/2-in. and 5/8-in. boards) the best method is to use a shooting board (Fig. 26). It must be noted, however, that a shooting board and plane practically never give a true right angle, owing to wear and the grinding of the blade. Therefore, the boards _should not_ all be laid with the "face mark" on the shooting board whilst the edges are shot, because any inequality would be multiplied by the number of pieces jointed. A better method is to alternate the boards, face side up, then face side down, whilst shooting the edges; this will prevent convexity or concavity on the face of the jointed board, because any slight error in the angle is neutralised (see Fig. 8).

APPLICATIONS OF THE JOINT.--The following show various applications of the b.u.t.t or glued joint:--

[Ill.u.s.tration: Fig. 14.--Carcase Wing-pieces Glued on.]

Fig. 7A shows a mahogany or other hardwood slip glued on the edge of a cheaper wood, such as pine or whitewood, as is the case on bookcase shelves when only the front edge is seen and polished.

Fig. 7B shows a moulding glued on a shelf, both mould and shelf in this instance being of polished hardwood. A shelf of this type might be used in a recess, the object of the overhanging moulding being to hide a small 3/8-in. iron rod which would carry the curtain rings and heading of the curtain which covers the recess. The shelf would be fixed about 3 ft. 9 ins. to 4 ft. 3 ins. from the floor.

Fig. 14 shows the wing pieces glued on the top bearer of carcase work.

The application of this bearer in its position will be shown in the chapter on Dovetailing.

Fig. 15 shows a b.u.t.t joint planed at an angle of 45 degrees (commonly called a mitre), used for box feet, etc.

Fig. 16 shows jointing up of an ogee-shaped panel. The dotted lines indicate the thickness of the timber previous to its being worked up to the finished shape. Bow-fronted and semicircular panels are jointed in a similar manner.

[Ill.u.s.tration: Fig. 15.--b.u.t.ting Mitred Angle Joint.]

[Ill.u.s.tration: Fig. 16.--Jointing Ogee-shaped Panel.]

Fig. 17 shows timber jointed at right angles to the upright piece, and at an angle of 30 degrees.

Fig. 18 indicates quarter-circle jointing, as used in round-cornered chests of drawers, wardrobes, cupboards, etc.