Woodwork Joints: How They Are Set Out, How Made and Where Used.

DOVETAIL GROOVING

The dovetail housing joint should first be carefully marked out with a marking knife, so as to cut across the fibres of the wood. For obtaining the bevel on the edge of the wood a joiner's bevel may be used, and the angle should not be too acute. (See previous chapter.) Take a chisel and pare away a small channel as at A, Fig. 315, to form a small shoulder to guide the saw.

With a fine tenon or dovetail saw, cut the saw kerf as at Fig. 316. If any difficulty is experienced in cutting the kerf true and square, you may resort to the method shown at C, Fig. 315; a small temporary piece of timber has been screwed on the top of the work to form a guide for the saw.

Fig. 315, B, shows the small channel formed by the chisel prior to the sawing operation. The sawing of the bevelled side is worked in a similar manner; but occasionally we find amateurs who adopt the method shown at Fig. 318. A block of wood (H) is first made by boring a 11⁄4-in. hole through its entire length, and afterwards making a saw cut at the desired bevel. The object of this block, which is kept specially for the purpose, is to form a guide for those who have not full control of the dovetail saw; the back of the saw clears the hole, and the required bevel is obtained. When a saw cut has been made at each side of the groove, the surplus timber is pared away in the following manner: Cut away portion E, Fig. 319; then cut away portion F, and lastly cut away the apex portion marked G. Continue by this method of paring until the approximate depth is reached. To ensure a correct depth throughout the entire groove, the router plane (or, as it is often called, "the old woman's tooth plane," Fig. 317) is used.

With regard to cutting the alternate piece, it is necessary to first plane the end of the shelf true and square. With a cutting gauge strike the line K, Fig. 320; the required bevel on the edge (J) is then set out, and with the chisel a small channel is again formed. With the tenon or dovetail saw cut down the line K to the required depth, and carefully pare away the wood with a sharp chisel to the correct shape.

THE MITRED JOINT

Although mitreing is used in everyday woodwork, it comes last in our list of regular joints simply because it has been partly dealt with in almost every previous chapter. For example, we have mitre halving in Fig. 34, a mitre bridle joint in Fig. 74, a tongued and grooved mitre in Fig. 116, mitred mortise and tenon joints in Figs. 148 and 159, a dowelled mitre frame in Fig. 202, and a mitred dovetail in Fig. 286.

Mitreing.—The term mitreing is generally used to denote the type of joint used at the corner of a picture frame; or where two pieces of wood are bevelled away so as to fit each other, as the skirting or plinth mould at Fig. 321. In these cases the timber is cut so that the joint is at 45 degrees to the face, and the two pieces, when placed together, form an angle of 90 degrees (a right angle).

The term mitreing, however, is not confined to the fitting of timber around a right angle; it may be justly applied to the fitting of a moulding around an angle irrespective of the number of its degrees.

One often hears such terms as "a half mitre," used to denote the fitting of a moulding around an octagonal column or pedestal, and probably it would be more correct to describe the joint as a mitre cut at 221⁄2 degrees. Mitreing consists of halving the angle and making each piece to fit the line of bisection. Should the angle be bounded by straight lines, as at Fig. 321, then the mitred joint will be a straight line, but should the angle be bounded by a curved and a straight line, as at Fig. 322, A, or by two curved lines, then the mitred joint will have to be a curved line if the mouldings are to be of the same section.

Finding the Angle.—For straight mitres, the mitre joint line is found by bisecting the angle, as shown in the various examples, and the following instructions are given to enable the reader to follow the diagram (Fig. 323). Take a pair of compasses, or dividers, and with any convenient opening strike out the arc A, B. Put the point of the compasses on A, and mark another arc C; then, without altering the distance between the points of the compass, put the point on B, and mark the arc D. Draw the line E from the corner, so that it cuts through the intersection made by the arcs C and D. The angle A B is now halved by the line E, and this method may be applied to any angle.

Sawing Block.—For sawing mouldings, etc., to their approximate shape, a home-made sawing block is generally used, as shown at Fig. 324. Two pieces of wood are glued one on the top of the other, the required angle is transferred thereto, and the saw kerf made. In the sketch the saw kerfs are shown at 45 degrees, right and left, and other angles and kerfs may be made where desired.

Planing.—After sawing the piece to approximately the correct angle, it is necessary on high-class work to plane the cut end so as to give a perfect finish and enable a glued joint to be made. This may be accomplished by using the plane on the shooting board, as shown at Fig. 325, and, if the worker is constantly using mitres of various angles, it is an easy matter to make new angle blocks and fix them on to the board. Other workers prefer the screw mitre trap shown at Fig. 326. This apparatus takes wide plinth or cornice moulds, and the angle may be altered by fitting temporary packing pieces under the work so as to tilt the moulding to the desired angle. The method of using the plane is indicated in the illustration.

Another method in everyday use by those workers who are constantly mitreing wide pieces of stock at 45 degrees is the "donkey's ear" shooting board illustrated at Fig. 327. The plane is laid on its side on the surface of the board marked A, and used in a similar manner to that shown at Fig. 325.

A simple method and one that should always be remembered because it is handy when working without a shooting board is shown at Fig. 328. Set the marking or cutting gauge to the thickness of the wood to be mitred at 45 degrees; then gauge this distance on the wood, as shown at B; draw from the line to the edge, as shown, and saw and plane to a finish. The diagonals of a square give 45 degrees, and this is the method used to mark out the work. The end of the wood must, of course, be square with its edges before marking out in this manner.

Fig. 329 shows a bevelled framing into which has been mitred a narrow moulding M so as to show a correct margin around the panel.

Fig. 330 shows a similar framing, but with a wide moulding M mitred around it. To obtain a correct intersection of this moulding, the angles A and B are bisected. The bisection of the angles meets before the width of the moulding is cleared, therefore the angle C will again have to be bisected, and the finished joint will appear as shown. One of the simplest of mouldings with a large flat face has been chosen to illustrate this. The moulding could be all in one width, as shown, or it could be built into the framing in separate pieces, the wide flat and the piece carrying the mould.

Curved Mitres.—We now come to what are probably the most difficult of all mitres, viz., curved mitres, and the writer well remembers in his apprenticeship days his first experience of attempting to fit the mouldings around the door shown at Fig. 331 by using straight mitres at A. This, of course, is impossible if the mouldings are of the same section and it is desired to make all the members correctly intersect. If straight mitres are used the section of the curved moulding will have to be of a different shape from the section of the straight moulding, and in these days of machine-made mouldings this method is seldom resorted to. It is better, cheaper, and easier to make curved mitres when the necessary machinery is at hand.

To Set out a Curved Mitre (see Fig. 332).—Draw a section of the moulding full size, A, as shown at the left hand of the illustration, and project lines round the framing, as shown V, W, X, Y and Z. Where the lines V, W, X, Y and Z intersect at the corner D, it clearly shows that a straight mitre will not cut all the points of intersection. A curved line will cut all the intersections, and a template made of cardboard, sheet zinc, or veneer, should be made to this shape. At the left-hand side the geometrical setting out is shown for obtaining the curve without having to resort to drawing it freehand.

Take half the width of the moulding, as shown by dotted line A, and where it cuts the approximation of the curved mitre place the point of the compasses and strike out a circle as shown; with the same radius place the compass point on B—that is, the inside point of the mitre, and cut the circle on the right and left with the small arcs shown at aa. With the same radius put the compass point at the junction of the circle and mitre line, C V, and cut the circle at right and left, viz., ee.

Now rule a line through aa, and another line through ee, and where these lines cut each other it will give the correct radius of the curved mitre. The advantage of knowing the correct radius of a curved mitre is of great benefit to the skilled machinist, as it enables him to set up his machine so as to give a definite result.

Mitreing a Moulded Door Frame.—Fig. 333 illustrates the method of mitreing the moulded portion of a door frame where the joint is dowelled, not tenoned. A small wooden template is made out of beech or other hardwood, having its ends cut at 45 degrees. This template is placed on the rail, as shown, and held in position by placing both the rail and the template in the vice. The face of the template forms a guide for a wide chisel, and enables the worker to gradually pare away the moulding to the correct angle.

For sawing the mitres on large mouldings such as are used on the lid of a gramophone or wireless cabinet, a mitre sawing box and a panel saw may be used as indicated at Fig. 334.

JOINTS FOR CURVED WORK

Fig. 335 shows a circular frame made up in two thicknesses, the segments being screwed to each other and the joints crossed in two layers. This is a very strong method, and it is used for making circular frames and curbs up to 15 ft. in diameter. The segments can be either long or short, the only important condition being that they must be marked out and sawn to the correct radius. Fig. 337 shows a board marked out in segments for this class of work. The longer the boards the better will they cut up, as it gives more opportunities of cutting one piece out of the other as at A A.

Fig. 338 shows how to begin to put the work together. To continue this, fit other segments in position and screw them to D and E respectively. The completed work is illustrated at Fig. 335.

Method of Building up Semicircular Head of Door Frame.

Fig. 336 shows a circular rim, or curb, made of segments which are halved together. This method is suitable for heavy work, where the timbers are of considerable size. The halvings are cut on the ends of the segments to any convenient shape or bevel, each one being marked so as to fit its fellow.

When extra length is required, semicircular or circular work is built up out of four or five thicknesses of wood, and the method is called laminating. The method of building up the semicircular head of a door frame by this method is shown at Figs. 339 and 340.

The shaped framing for kidney-shaped writing tables and similar classes of work is built up by laminating pieces of 3⁄4-in. or 1-in. wood, after which the face side is veneered so as to hide the glued joints. Fig. 341 shows a sketch of one quarter of an elliptical table frame levelled up and ready for applying the veneer.

Lamination.—If we apply to the dictionary for the word "lamination," we find that lamellar structure is the arrangements in thin plates or layers one over the other, usually having the end joints alternating, and it is a condition which allows of cleavage in one direction only. This method is used for nearly all descriptions of free or irregular curves, such as sweeps, bends, ogee shapes, and segments of circles. The timber is marked out in suitable lengths, rough-sawn and then planed true on the face, glued together, and when set the sides are cleaned up to the required shape. It is one of the strongest methods of construction, and necessarily costly. Pulleys, pulley rims, and a hundred and one other jobs are built by this method.

Fig. 342 shows one half of a core box built by this method, ready to be worked to the required shape.

MISCELLANEOUS JOINTS

Weather boards.—For outdoor buildings, such as garages, garden sheds, toolhouses, etc., "weatherboarding" is often preferred to ordinary matchboarding, chiefly because of the facility with which it throws off the rain. The boarding can be bought ready prepared. Three methods of jointing are shown in the sections at Fig. 343. The method indicated at A shows one of the most satisfactory types, its boards being planed and moulded as shown. The other two examples are more common. The boarding at B is rebated, whilst at C each board overhangs its lower neighbour. The boards for C and D are always cut tapered as indicated.

The end grain is usually protected by nailing on a strip of timber, chamfered on both edges.

Ladders.—Fig. 344 illustrates the method of fastening the rung (or stave) of a ladder to the side. At A the common method is shown, the stave being simply driven into the hole and wedged. At B a much better but more expensive method of construction is given. The stave here is socketed and the pin turned to a smaller diameter. In both cases the rung, or stave, is painted before being driven into the side and wedged.

Ladder sides are made in two distinct ways. One method is known as "a plank side," the side being cut from a plank as shown at the section D; the other method is called "a pole side," and is constructed by cutting a straight larch pole in half and using half of the pole for each side of the ladder, as at section C.

Hinged Cornice Poles.—Fig. 345 shows a hinged joint for cornice poles and should be of interest to those who are frequently removing from house to house. The joint will adapt itself to fit any bay window (even a square bay) and it is formed by turning and cutting the two pieces shown. To fix a cornice pole to a bay window one of these joints is required for each angle of the bay, the pole being cut into suitable lengths and fixed to the hinged joints by the use of the dowel screw and a little hot glue. It is perhaps needless to remark that the diameter of the joint should be of the same diameter as the cornice pole, to enable the rings to easily slide over the surface.

For fastening a turned ornament (or "finial") to the end of a cornice pole a double pointed screw (known in the trade as a "dowel screw") is used, one half of which is screwed into each part of the pieces to be joined.

Veneer Keying.—Fig. 346 illustrates the method of strengthening the corners of boxes which are made of 1⁄4-in. or 3⁄8-in. timber, by securing the corners with veneer keys. The box is mitred and glued in the usual manner, and after allowing sufficient time for the glue to set, saw kerfs are made as shown at a a. A piece of thin saw-cut veneer is afterwards glued into the saw kerfs, and when dry the face is levelled off flush. This method is often used previous to veneering the face side of the box with rare veneers, and it is also useful for repair work. Note that the saw cuts are made at an angle. Small picture frames are sometimes keyed instead of nailed.

Muntin and Skirting Joint.—In the case of panelled rooms it is usually necessary to scribe the muntins (or uprights) to the skirting. The method is shown in Fig. 347. The bead moulding of the skirting is only partly removed, as indicated, leaving a solid portion to which the muntin is skew-nailed.

Cot Joint.—At Fig. 348 is shown an interesting joint used largely in the making of Indian cots. The illustrations indicate how the cross bar and end bar are mortised into the leg. A turned hardwood peg fits into a suitably provided hole and locks the tenons, which are dry jointed (not glued) in position. The head of this peg forms an ornament (A) at the top of the leg and should fit tightly in position. At B are seen the end and cross bars in their relative positions when apart from the leg. C shows the end bar and cross bar when the cot is fixed, but in this illustration the leg is purposely left out of the drawing for a clear representation. D shows the joints of the leg portion when the part of the leg above the line at A is sawn off. The hardwood peg is shown at E.

Sideboard Pillars, etc. (Fig. 349).—For economy, sideboard pillars are sometimes built up as indicated, the "shaft," the "base," and the "swell" being made up of three distinct pieces. Turned pins are left on the shaft and the base, and these are secured at the joint by the use of a double-pointed screw called a dowel screw. This does away with the necessity of reducing the squares at the top of the wood and thus getting the turning out of a large piece of wood.

Notched Joints.—Fig. 350 is a "notched joint," where two joists, or scantlings, cross each other, the object of the joint being to prevent the joists moving from their position without materially weakening them. For an end notch, see Fig. 352.

The "saddle joint" (Fig. 351) is used for connecting upright posts to heads or sills of framing, and undoubtedly takes its name from its similarity to the way in which the saddle fits the horse. It does not weaken the framing as does a mortise and tenon joint, and shrinkage has little effect upon the joint. The "cogged joint," used for connecting purlins to rafter and joists to girders, is illustrated in Fig. 353.

Birdsmouth Joints.—Fig. 354 is a "birdsmouth joint," a simple joint which can be readily made by the handsaw, used when a spar fits on the wall plate. A nail is shown securing it in position.

Fig. 355 shows the birdsmouth joint where the spar runs over the outside of the wall plate, thus allowing a fixing for an ornamental finish.

Rafter Joint.—Fig. 356 shows an everyday joint, as used at the juncture of the principal rafter and the tie-beam in roof truss work. A sketch of piece A is shown separated, and it should be noted that the depth of the cut portion B should not be more than one-fourth of the total width of the tie-beam.

Pelleting.—Fig. 357 indicates the method of pelleting and screwing the corner of a picture frame. The mitre joint is first screwed and a pellet of the same timber is made to fill the hole which has been bored to receive the screw head. The pellet is glued in position and levelled off.

Patera Covers.—In cases where the style of ornament permits of it, patera covers are used instead of pelleting. Fig. 358 shows the jointing of shaped spandrails, etc., to carcase ends of light portable cabinet work, etc. A hole is bored about 3⁄8 in. deep into the end, and a screw is used to hold the shaping in position. After fixing the rail a small turned button, called a turned patera, is inserted in the hole, thus giving an ornamental finish, as shown in the front view. The turned patera is driven fairly tightly into the hole, but not glued. When it is required to take the article apart a chisel is carefully inserted under the edge of the patera to remove it, and the screw can then be taken out. This method is often used for the construction of light hanging bookcases and similar objects. For a bookcase having an end 8 ins. wide three of these turned buttons and three screws would be used to secure the shelf to the end. Pateras in different styles may be purchased from any dealer in woodworking sundries.

Buttoning.—The tops of tables, sideboards, etc., should not be fixed with screws in the ordinary way. At the front, screws can be driven upwards through the top rail, but at the sides and back, buttons should be employed, as in Fig. 359, so that the top is free to shrink. It is otherwise liable to split if immovably fixed. The tops of kitchen tables are usually fixed in this way, to allow for shrinkage.

Frames for Oil Paintings.—The method of making joints for frames on which the canvas is stretched for oil paintings is shown at Fig. 360. They are generally mitred at the corners and fitted with loose wedges. The four parts of the frame can be held temporarily by a piece of thin board while the canvas is being tacked to the edges of the frame. In the accompanying illustrations Fig. 360 shows the action of the wedges when tightening up the frame, the result being to open the mitre joint. Fig. 361 shows the position of the saw cuts for receiving the hardwood wedges. Note that the parallel groove is carried the full length of the material for greater convenience in cutting. The other groove is taken from the outer angle of the mitre joint inwards. The cut finishes with due regard to the necessary taper; see the dotted lines showing taper in Fig. 360. The grooves will be wide enough after being cut with an ordinary hand-rip saw, but for large work they are usually grooved on the circular saw bench.

Joint and Method of Wedging the Frames of Oil Paintings.

Corrugated Steel Fasteners.—It is now many years ago since the steel saw-edge fastener first appeared on the market, but probably 80 per cent. of amateur woodworkers have never yet sampled its advantages.

In appearance it resembles a miniature corrugated galvanised sheet such as is used for roofing purposes, with the exception, however, that the corrugations are divergent instead of being parallel and that one end is ground down to a cutting edge (see Fig. 363, A). They are made in various sizes from 1⁄4 in. to 1 in. in length, whilst in regard to width they are classed by the number of corrugations and not by their measurement.

The Use of Saw-edge Corrugated Steel Fasteners.

To use the fastener no special tools are required; it is simply driven in with a hammer exactly as though it were a nail; once in position, however, to get it out is worse than drawing teeth. The corrugations add to the strength of the device, the wood fibres closing around them, age and rust but emphasising their grip.

Wall Plugs.—At Fig. 364 four types of wall plugs are shown: a, the ordinary rectangular tapered wall plug to drive between the joints of the brickwork; b, the circular tapered wall plug as used to plug a wall after a star-shaped brick drill has been used; d, a twisted wall plug used for similar purposes to the wedge a, but considered to be superior in holding power owing to its twisted formation; c is another type of wall plug considered to have great tenacity by reason of its corrugations. Wall plugs are required in nearly all cases where it is necessary to joint woodwork to brickwork, as, for instance, heavily-framed silvered mirrors to the walls of shops.

Slot Screwing, or Keyhole Screwing, is a most useful way of joining light woodwork in such a manner that the fixing method is not exposed to the eye. A stout screw is inserted to within 3⁄8 in. of the head, as at Fig. 365. In the adjoining piece a hole is bored with a centre bit and a slot is cut with an 1⁄8 in. chisel. The two pieces of timber are placed together, and by sliding the upper piece forward the screw runs up into the slot or keyhole and secures the joint. Fig. 366 shows the application of the joint fixing a shaped bracket to the shaped shelf; the bracket and shelf are inverted in the illustration to clearly show the method of jointing. For heavy work special brass plates are obtainable for this purpose; one plate is let flush into the upper piece and the other plate into the lower piece.

Battening (Fig. 367).—A good method of joining cross battens to drawing boards and other wide surfaces is shown here. After boring for the screws, slots are cut so as to allow the screws to move along the slots when shrinkage takes place. In Fig. 368 a similar method is applied to secure the drawer bottom to the drawer back. If shrinkage takes place in the drawer bottom and it leaves the groove in the drawer front, the screws are slackened, the drawer bottom is knocked up into the groove, and the screws again inserted. For drawing boards, etc., specially made elliptical-shaped slotted brass socket cups are made to receive the screw heads.

PUZZLE JOINTS

Puzzle Joints are not only interesting in themselves, but are often excellent studies in craftsmanship. The majority of them, if to be satisfactory as puzzles, call for very careful setting out and cutting, entailing the same degree of skill that is demanded for high-class cabinet work. For this reason several examples may well find a place in a volume dealing with woodwork joints. As a rule, these puzzles should be made in hardwood, such as dark walnut or beech, as in whitewood the joints are soon liable to wear.