Cassells' Carpentry and Joinery/Joints

by C. W. D. Boxall, Henry Adams, F. W. Loasby

JOINTS.

Introduction.—Full instructions on setting out, cutting, and fitting most of the joints used in carpentry and joinery are given in the companion volume, "Woodworking," and the reader is assumed to be familiar with all these processes. The object of the present chapter is merely to present brief particulars of the joints in general use and to provide a collection of illustrations handy for reference, so that the present treatment of technical woodworking may not be incomplete.

Fig. 178.— Straight Halved Joint.

Fig. 179.— Angle Halved Joint.

Fig. 180.— Angle Halved Joint, Apart.

Fig. 181.— Cross-halved (or Cross Lap) Joint.

Fig. 182.—Dovetail Lap Joint.

Fig. 183.—Bevelled Halving.

Fig. 184.—Shouldered Dovetail Halving.

Fig. 185.— Single Notching.

Fig. 186.—Double Notching.

Fig. 187.— Dovetail Notching, Wedged.

Fig. 188.—Dovetail Notching.

Joints in Carpentry.

Halved Joints.—The simplest joints used in carpentry are the various forms of halving: simple halved joints (Figs.

Fig. 189.— Tredgold Notching.

Fig. 190.—Cogging.

Fig. 191.—Bird's-mouthed Joint.

Pig. 192.— Bridle Joint.

Fig. 193.— Oblique Bridle Joint.

Fig. 194.— Dowelled Post and Sill.

Fig. 195.—Stump or Stub Tenon.

Fig. 196.—Shouldered Tenon.

Fig. 197.— Divided Tenon.

Fig. 198.— Inserting Tenon in Chase Mortise.

to 181), dovetail halving (Fig. 182), bevelled halving (Fig. 183), and shouldered dovetail halving (Fig. 184).

Notched and Other Joints.—Of the many forms of notching there are: single notching (Fig. 185), double notching (Fig. 186), dovetail notching (Figs. 187 and 188), and Tredgold notching (Fig. 189). Cogging is shown by Fig. 190, the bird's-mouthed joint by Fig. 191, the bridle joint by Figs. 192 and 193, and dowelling of wood to stone by Fig. 191.

Tenon Joints (Carpenters').—Of tenon joints there is the stump, or stub tenon (Fig. 195); the shouldered tenon (Fig. 196); the divided tenon (Fig. 197); the chase mortise (Fig. 198), in the side of a timber, with one cheek cut away and the depth gradually tapering out to the face of the

Fig. 199.—Section of Tusk Tenon Joint.

Fig. 200.—Parts of Tusk-tenoned Joint.

Fig. 201—Wedged Tusk Tenon Joint.

timber. It is used in framed and doubled floors, for enabling short joists, such, as ceiling joists between the binders, to be got into place after the larger timbers are fixed, as shown in the illustration. The tusk tenon is shown by Figs. 199 to 201; struts tenoned into the heads of king- or queen-posts are shown by Figs. 202 to 204.

Toe Joints.—Simple toe joints are shown by Figs. 205 and 206, and a toe joint with tenon by Fig. 207.

Fig. 202.—Strut Tenoned into King- or Queen-Post.

Fig. 203.—Principal Rafter Tenoned into Queen-Post, Straining Beam Joggled into same.

Fig. 204.—Principal Rafters Tenoned into King-Post.

Fig. 205.—Toe Joint between Principal Rafter and Strut.

Fig. 206.—Toe Joint between Vertical Post and Strut.

Gantry Strut Joints.—Bird's-mouth and mitred butt joints for a gantry strut are shown by Figs. 208 and 209 respectively.

Fig. 207.—Toe Joint with Tenon.

Fig. 208.—Bird's-mouth Joint between Strut and Straining Piece, or Head.

Fig. 209.—Mitre Butt Joint between Straining Piece and Strut.

Fig. 210.—Dovetailed Halving Bolted.

Fig. 211.—Common Fished Joint.

Fig. 212.—Lapped Joint with Keys and Straps.

Fig. 213.—Raking Scarf with Butt End.

Fig. 214.—Tabled Joint.

Fig. 215.—Tabled Scarf with Folding Wedges.

Fig. 216.—Tabled and Splayed Scarf.

Fig. 217.-Indented Beams for Lengthening and Strengthening.

Fig. 218.—Splayed Scarf with Folding Wedges.

Fig. 220.—Fished and Tabled Joint.

Fig. 221.—Fished and Tabled Joint.

Joints for Lengthening Beams and Posts.—A joint suitable for tension only is the dovetailed halving (Fig. 210). A joint suitable for compression only is the common fished joint (Fig. 211). Joints suitable for cross strain only are as follows: Lapped, with keys and straps (Fig. 212), and the raking scarf with butt end (Fig. 213). Joints suitable for tension and compression are as follows: Tabled (Fig. 214), and the tabled scarf with folding wedges (Fig. 215). Joints suitable for tension and cross strain are as follows: Tabled and splayed scarf (Fig. 216), indented beams for lengthening and strengthening (Fig. 217), and the splayed scarf with folding wedges and iron plate covering joint on tension side (Fig. 218). A joint suitable for compression and cross

Fig. 222.—Tabled Scarf with Keys and Plates.

Fig. 223.—Fished Joint, Keyed and Bolted.

Fig. 224.—Fished Joint with Hardwood Keys.

Fig. 225.—Splayed Scarf with Folding Wedges and Iron Fish Plates.

Fig. 226.—Dovetail Splayed Joint.

Fig. 227.—Dovetail Scarf.

Fig. 228.—Raking Scarf used for Ridges, etc.

Fig. 229.—Vertical Scarf.

Fig. 230.—Double Halved or Double Forked Joint Together.

Fig. 231—Double Forked Joint Apart.

Fig. 232.—Parallel Scarf with Joggled Ends.

Fig. 233.—Splayed Scarf.

Fig. 234.—Single Fished Butt Joint when Post is Braced.

Fig. 235.—Double Fished Butt Joint for Detached Post.

strain is the fished joint with oblique keys (Fig. 219). Joints suitable for tension, compression, and cross strain are as follows Fished and tabled (Figs. 220 and 221) tabled scarf, with keys and plates (Fig. 222) fished, keyed, and bolted (Fig. 223); fished, with hardwood keys (Fig. 224); and the splayed scarf with iron fish plates and bolts (Fig. 225), which is used in the warehouses at the South-West India Dock, London. Other joints used for lengthening plates and ridges are shown at Figs. 226, 227, and 228. Joints for beams and posts are: the vertical scarf—a halved joint (Fig. 229), double halved joint (Figs. 230 and 231), parallel scarf with joggled ends (Fig. 232), splayed scarf (Fig. 233), single fished butt joint when the post is braced (Fig. 234), and the double fished butt joint (Fig. 235) when the post is detached.

Fig. 236.—Tabled Scarf Joint.

Rule for Proportioning Parts of Scarf.—Tredgold gives the following practical rules for proportioning the different parts of a scarf according to the strength possessed by the kind of timber in which it is formed, to resist tensional, compressional, or shearing forces respectively. In Fig. 236 c d must be to c b in the ratio that the force to resist detrusion bears in the direct cohesion of the material—that is, in oak, ash, elm, c d must be equal to from eight to ten times c b; in fir and other straight-grained woods c d must be equal to from sixteen to twenty times c b. The sum of the depth of the indents should be equal to one and one-third depth of beam. The length of scarf should bear the following proportion to the depth of the beam:—

Wood Used	Without bolts	With bolts	With bolts and indents
Hardwood (oak, ash, elm)	6 times	3 times	2 times
Fir and other straight-grained woods	12 „	6 „	4 „

Calculation of a scarfed joint with folding wedges as Fig. 237: —

Per sq. in.
Working	resistance	to	tearing	=	12	cwt.
„	„		compression	=	10	„
„	„		shearing	=	1.3	„

Load equals, say, 360 cwt. direct tension beyond that taken by bolts or plates. The joint may tear across a b or d e (Fig. 237), therefore section at a b must equal 360/12 = 30, say 10 in. by 3 in. The joint may also shear across b c or g f, therefore section at b c or g f must equal 360/1.3 = 277, say 28 in. by 10 in. The joint may also be crushed at b d or g h, therefore section at b d or g h must equal 360/10 = 36, say 10 in. by 3½ in. Thus the beam should be about 10 in. by 10 in., with wedges as shown; but in ordinary practice the folding wedges do not exceed one-fourth the depth of the beam, and are usually placed square to the rake of the scarf, the scarf being further strengthened by bolts and plates.

Strength of Joints in Struts and Beams.—If two deals are bolted together, with distance pieces between, they will be stronger than a solid timber strut of the same sectional area, because the dimension of "least width" in the formula for calculation of strength will be increased. There

Fig. 237.—Splayed Scarf with Folding Wedges.

would be no appreciable advantage in making the distance pieces of different thicknesses, to swell or reduce the middle diameter; they should be all alike, and enough to make the combined thickness not less than three-fourths of the width of the deals, and the distance apart in feet should be equal to the length of the deal in feet multiplied by its thickness in inches and divided by the width in inches. Single ½-in. bolts are of no use in rough carpentry, except for very small work; instead, two ⅝-in. bolts should be placed diagonally through each block. Horizontal connecting rods in machinery are sometimes swelled in the middle to allow for the cross strain upon

Figs. 238 and 239.—Connecting Post and Beams by Tenoning and Cogging.

Figs. 240 and 241.—Securing Joints between Post and Beams by Straps and Bolts.

Figs. 242 and 243.—Joints and Fastenings between Post, Corbel and Beam for Heavy Stage.

Fig. 244.—Alternative Method by using Two Cross Beams

Fig. 245.—Upper Portion of Framing of Ordinary Staging.

Fig. 246.—Detail of Form of Staging stronger than that shown by Fig. 245.

Fig. 247.—Upper Portion of Staging Supporting Heavy Loads; Head Beam Halved and Bolted to Corbel.

them in addition to the end-long strain, while vertical struts have no cross strain to meet.

Fig. 248.—Conventional View of Staging with Head Beam Halved and Bolted to Corbel.

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. 238 to 254. The inscriptions to the illustrations make the methods quite clear to understand.

Joints in Joinery.

Edge Joints.—Eleven joints used in connecting boards edge to edge are shown by

Fig. 251.—Mitred Butt and Tenoned Joint between Brace and Straining Piece.

Fig. 252.—Double Abutment Joint between Strut, Head, and Straining Piece.

Fig. 253.—Treble Abutment Joint between Strut and Straining Piece.

Fig. 254.—Tenoned and Bird's-mouth Shouldered Joint between Strut and Straining Piece.

Figs. 255 to 265. Matchboarding is thin stuff with a tongue and bead worked on one edge and a groove on the other, so that when the pieces are put together the joint is masked by the bead, and the tongue prevents dust and draught from passing through, as in Fig. 263. A slip feather is a piece of wood inserted in plough grooves, as in Fig. 260, to strengthen a glued joint, or to keep out the dust. It may be of soft wood, and is then in short lengths, made by cutting pieces 1 in. wide off the end of a plank, turning the pieces over, and cutting them into thin strips, with the grain across their length. If hard wood is used, the grain may run in the direction of the length. The slip feathers may also be double, or dovetailed.

Fig. 249.—Strut and Post Joint Supported by Cleat Spiked to Post.

Fig. 250.—Brace and Post Joint. Brace Tenoned into Post: Cleat Joggled in and Spiked to Post.

Right Angle Joints.—Fourteen styles of angle joints are shown by Figs. 266 to 279.

Obtuse Angle Joints.—Four kinds of these joints are illustrated by Figs. 280 to 283.

Dovetail Joints.—These are known in great variety, but it will be sufficient to show a few kinds only: the ordinary

Fig. 255.—Edge Butt Joint.

Fig. 256.—Rebated Joint.

Fig. 257.—Rebated and Filleted Joint.

Fig. 258.—Grooved and Tongued Joint.

Fig. 259.—Rebated, Grooved, and Tongued Joint.

Fig. 260.—Ploughed and Cross Tongued Joint.

Fig. 261.—Dovetail Slip-feather Joint.

Fig. 262.—Matched and Beaded Joint.

Fig. 263.—Matched and Vee Jointed.

Fig. 264.—Splay-rebated Joint.

Fig. 265.—Dowelled Joint.

dovetailing (Figs. 284 and 285), lapped dovetail (Fig. 286), two secret or double-lap or rebated dovetails (Figs. 287 and 288), and the secret mitred dovetail (Fig. 289). The box pin joint (Fig. 290) is not a dovetail joint, but has some of the latter's characteristics. The dovetail ledged and the diminished dovetail ledged are shown respectively by Figs. 291 and 292.

Dowelled Joint.—The ordinary dowelled joint is represented by Fig. 293; sections showing a dowel fitted incorrectly and correctly are represented by Figs. 294 and 295 respectively. A right angle dowelled joint is shown by Fig. 296. Allied to the dowel joint is the screwed straight joint (Figs. 297

Fig. 266.—Plain Butt Joint.

Fig. 267.—Rebated Butt Joint.

Fig. 268.—Plain Mitre Joint.

Fig. 269.—Butt Joint Tongued.

Fig. 270.—Mitre Joint Tongued.

Fig. 271.—Rebated and Mitre Joint.

Fig. 272.—Mitred, Grooved, and Tongued Joint.

Fig. 273.—Rebated, Mitred, and Double-tongued Joint.

Fig. 274.—Rebated, Tongued, and Staff Beaded Joint.

Fig. 275.—Rebated and Grooved Joint to Nosing.

Fig. 276.—Glued Blockings.

Fig. 277.—Butt Joint with Beads.

Fig. 278.—Flush Rebated and Staff Beaded Joint.

Fig. 279.—Rebated, Grooved, and Staff Beaded Joint.

Fig. 280.—Obtuse Angle Grooved and Tongued Joint, with Bead to Break Joint.

Fig. 281—Obtuse Angle Rebated Joint.

Fig. 282.— Obtuse Angle Mitred, Grooved, and Tongued Joint.

Fig. 283.—Obtuse Angle Rebated, Grooved, and Staff Beaded Joint.

Fig. 284.—Box Dovetail Joint formed by Several Boards.

Fig. 285.—Box Dovetail Joint.

Fig. 286.—Lapped or Drawer Dovetail Joint.

Fig. 287.—Secret Lap Dovetail Joint.

Fig. 288.—Secret Lap Dovetail Joint.

Fig. 289.—Secret Mitred Dovetail.

Fig. 290.—Box Pin Joint.

Fig. 291.—Dovetail Ledged.

Fig. 292.—Diminished Dovetail Ledged.

Fig. 293.—Dowelled Joing.

Fig. 294.—Dowelled Joint with Excessive Countersinking and Rounding.

Fig. 295.—Dowelled Joint Correctly Made.

Fig. 296.—Dowelled Angle Joint.

Fig. 297.—Screwed Joint Complete.

Fig. 298.—Screwed Joint, before Sliding into Position.

Fig. 299.—Edges of Boards to be Screw Jointed.

Fig. 300.—Sectional View of Screwed Joint.

to 300); the screw heads enter the holes bored for them, the edge is then slotted for about ¾ in. beyond the hole to allow the stem of the screw to pass along, the head projecting beyond the stem forms the key, and then the boards are merely slid together tightly, so forming a strong joint which can be taken apart easily.

Fig. 301.—Housed Joint.

Fig. 302.—Open Mortise and Tenon Joint.

Fig. 303.—Tenon and Mortise Joint.

Fig. 304.—Pair of Single Tenons.

Fig. 305.—Double or Twin Tenons.

Fig. 306.—Pair of Single Tenons with Grooves and Slip Feathers.

Fig. 307.—Haunched Tenon.

Fig. 308.—Dovetail Tenon.

Fig. 309.—Pinned Tenon.

Fig. 310.—Foxtail Tenon.

Housing.—The simple housing joint is shown by Fig. 301.

Tenon Joints (Joiners').—Some tenon joints have already been shown under the heading, "Joints in Carpentry" (p. 55). Further tenon joints, more especially used in joinery, are: the simple open tenon and mortise (Fig. 302); closed mortise and tenon (Fig. 303); pair of single tenons, commonly called "double" tenons (Fig. 304); double or twin tenons (Fig. 305); pair of single tenons, with grooves and slip feathers (Fig. 306); haunched tenon (Fig. 307); dovetail tenon (Fig.. 308); pinned tenon (Fig. 309). Stump or stub tenons and tusk tenons are also used in joinery, and have already been illustrated (Figs. 195

Fig. 311.—Foxtail Tenons with and without Housing.

and 200, pp. 55 and 56). The foxtail tenon (Fig. 30) is a good joint; alternative methods (with and without housing) of applying this in fitting rails into an oak gate-post are shown by Fig. 311.

Proportioning Tenons.—There is no universal rule for proportioning tenons, but the practice is to give from half to the whole of the width of the rail, when this does not exceed 5 in., for the width of the tenons. If more space than half were given to a haunched tenon, the end of the stile would be liable to be driven out in wedging up, and there is no reason why more space should be given. Wide tenons are objectionable, owing to their liability to shrink from the wedges or the sides of the mortises.

Applications of Tenon Joints.—With regard to the application of the various tenon joints, a few of these are noted below: A simple tenon, one-third thickness of the stuff, is used in framing together pieces of the same size, the mortise being just long enough to allow of a wedge being driven in on each side of the tenon to secure it. A pair of single tenons, usually called a double tenon, is used for connecting the middle rail of a door to the stiles. A haunched tenon for connecting the top rail of a door to the stiles; the tenon being half the width of the top rail leaves a haunch or haunching to prevent the rail from twisting. A stump or stub tenon is used at the foot of a post to prevent movement. A tusk tenon is used in framing trimmers to trimming joists, to

Fig. 312.—Hammer-headed Key Joint.

obtain the maximum support with the minimum reduction of strength. A tenon with only one shoulder is used in framed and braced batten doors, and in skylights, when the rail requires to be kept thin for other parts to pass over; this is known as a barefaced tenon. A pair of double tenons is used for the lock rail of a thick door, to receive a mortise lock.

Hammer-headed Key Joint.—A conventional view of a hammer-headed key joint apart is presented by Fig. 312.

Special Joints.—Many other joints adapted to particular purposes are described in subsequent sections. Reference to these may easily be found by consulting the index.