Handwork in Wood Part 19

Varnish brushes need to be cleaned thoroly after each using. If they get dry they become too hard to be cleaned without great difficulty.

Brushes for water stains are easily taken care of by washing with water and then laying them flat in a box. Cups in which the water stains have been used can also be easily rinsed with water.

Brushes for oil stains are most easily kept in good condition, by being hung in a brush-keeper, Fig. 245, (sold by Devoe & Reynolds, 101 Fulton St., N. Y. C.) partly filled with turpentine. The same brushes may also be used for fillers.

Oil stains should be poured back into their respective bottles, and the cups wiped out with cotton waste. When they get in bad condition, they can be cleaned readily after a preliminary soaking in a strong solution of potash. The same treatment may be given to brushes, but if they are left soaking too long in the solution, the bristles will be eaten off.

[Ill.u.s.tration: Fig. 245. Brush-keeper.]

EQUIPMENT AND CARE OF THE SHOP

REFERENCES:[*]

Murray, _Year Book_ 1906, p. 69.

Bailey, _M. T. Mag._, 9: 138. Dec. '07.

Robillion, pp. 48-90.

Hammacher and Schlemmer, pa.s.sim.

[Footnote *: For general bibliography, see p. 4.]

CHAPTER VII.

THE COMMON JOINTS.

Wherever two or more pieces of wood are fastened together we have what is properly called joinery. In common usage the term indicates the framing of the interior wood finish of buildings and ships, but it is also used to include cabinet-making, which is the art of constructing furniture, and even the trades of the wheelwright, carriage-maker, and cooper. Since joinery involves the constant use of joints, a reference list of them, with ill.u.s.trations, definitions, uses, and directions for making typical ones may be of convenience to workers in wood.

HEADING JOINTS

_No. 1. A lapped and strapped joint_, Fig. 264, p. 177, is made by laying the end of one timber over another and fastening them both together with bent straps on the ends of which are screws by which they may be tightened. It is a very strong joint and is used where the beams need lengthening as in false work or in long ladders and flag poles.

_No. 2. A fished joint_, Fig. 264, is made by b.u.t.ting the squared ends of two timbers together and placing short pieces of wood or iron, called fish-plates, over the faces of the timbers and bolting or spiking the whole firmly together. It is used for joining timbers in the direction of their length, as in boat construction.

_No. 3._ In a _fished joint_, Fig. 264, keys are often inserted between the fish-plate and beam at right angles to the bolts in order to lessen the strain that comes upon the bolts when the joint is subjected to tension. In wide pieces and for extra strength, as in bridge work, the bolts may be staggered.

_Nos. 4, 5, 6 and 7._ _A scarf or spliced joint_, Fig. 264, is made by joining together with flush surfaces the ends of two timbers in such a way as to enable them to resist compression, as in No. 4; tension, as in No. 5; both, as in No. 6, where the scarf is tabled; or cross strain as in No. 7. No. 4 is used in house sills and in splicing out short posts, Nos. 5 and 6 in open frame work. _No. 7_ with or without the fish-plate, is used in boats and canoes, and is sometimes called a boat-builder's joint, to distinguish it from No. 4, a carpenter's joint. A joint to resist cross strain is stronger when scarfed in the direction of the strain than across it. No. 7 is the plan, not elevation, of a joint to receive vertical cross strain.

b.u.t.t JOINTS

_No. 8. A doweled b.u.t.t-joint_, Fig. 264, is made by inserting, with glue, dowel-pins into holes bored into the two members. The end of one member is b.u.t.ted against the face or edge of the other. It is used in cabinet-making where the presence of nails would be unseemly.

[Ill.u.s.tration: Fig. 246. Lay-out by Thru Dowling.]

In a doweled b.u.t.t-joint the dowels may go clear thru the outside member, and be finished as b.u.t.tons on the outside, where they show.

To lay out this joint mark near the ends of the edges of the ab.u.t.ting member, X, Fig. 246, center-lines A B. Draw on the other member Y, a sharp pencil-line to which when the lines AB on X are fitted, X will be in its proper place. Carry the line around to the other side of Y and locate on it the proper centers for the dowel-holes E and F. Then fasten on the end of X a handscrew in such a way that the jaws will be flush with the end. With another handscrew, clamp this handscrew to Y in such a way that the marks on the two pieces match, A to C and B to D, Fig. 247. Bore at the proper places, E and F, holes directly thru Y into X.

[Ill.u.s.tration: Fig. 247. Thru Boring for a b.u.t.t Joint.]

Fig. 248 ill.u.s.trates the gluing together of a four-legged stand in which the joints are made in this way. The cross-lap joints of the stretchers are first glued together, then the other joints are a.s.sembled without glue, to see that all the parts fit and finally two opposite sides are glued at a time. Pieces of paper are laid inside the gluing blocks to prevent them from sticking to the legs.

[Ill.u.s.tration: Fig. 248. Gluing-Up a Four-Legged Stand.]

In case the dowels are to be hidden the chief difficulty is to locate the holes properly. One method of procedure is as follows: To dowel the end of one member against the face of the other as a stringer into a rail or a rail into a table leg, first lay out the position of the dowels in the end of the first member, X, Fig. 249. Gage a center-line, A B, across this end lengthwise, locate the centers of the dowel-holes, and square across with a knife point, as CD and EF. Gage a line on the other member to correspond with the line AB. On the face so gaged, lay the first member on its side so that one arris lies along this gaged line and p.r.i.c.k off the points D and F, to get the centers of the dowel-holes.

[Ill.u.s.tration: Fig. 249. Laying out a Dowel Joint.]

If, as is usual, there are a number of similar joints to be made, a device like that shown in Fig. 249 will expedite matters. 1 and 2 are points of brads driven thru a piece of soft wood, which has been notched out, and are as far apart as the dowels. A-1 is the distance from the working edge of the rail to the first dowel. The same measure can be used from the end of the leg.

When the centers are all marked, bore the holes. Insert the dowels into the holes and make a trial a.s.sembly. If any rail is twisted from its proper plane, note carefully where the error is, take apart, glue a dowel into the hole, that is wrong, pare it off flush with the surface, and re-bore in such a place that the parts, when a.s.sembled will come up true. When everything fits, glue and clamp together.

_No. 9. A toe-nailed joint_, Fig. 264, is made by driving nails diagonally thru the corners of one member into the other. It is used in fastening the studding to the sill in balloon framing.

_No. 10. A draw-bolt joint_, Fig. 264, is made by inserting an iron bolt thru a hole in one member and into the other to meet a nut inserted from the side of the second member. It is very strong and is used in bench construction, wooden machinery, etc.

_No. 11. A plain b.u.t.t-joint_, Fig. 264, is one in which the members join endwise or edgewise without overlapping. It is used on returns as in ordinary boxes and cases.

_No. 12. A glued and blocked joint_, Fig. 264, is made by gluing and rubbing a block in the inside corner of two pieces which are b.u.t.ted and glued together. It is used in stair-work and cabinet-work, as in the corners of bureaus.

_No. 13. A hopper-joint_, Fig. 264, is a b.u.t.t-joint, but is peculiar in that the edges of the boards are not square with their faces on account of the pitch of the sides. It is used in hoppers, bins, chutes, etc. The difficulty in laying out this joint is to obtain the proper angle for the edges of the pieces. This may be done as follows: After the pieces are planed to the correct thickness, plane the upper and lower edges of the end pieces to the correct bevel as shown by the pitch of the sides. Lay out the pitch of the sides of the hopper on the outside of the end pieces. From the ends of these lines, on the upper and lower beveled edges score lines at right angles with the knife and try-square. Connect these lines on what will be the inside of the hopper. Saw off the surplus wood and plane to the lines thus scored. The side pieces may be finished in the same way, and the parts are then ready to be a.s.sembled.

HALVING-JOINTS

A halved joint is one in which half the thickness of each member is notched out and the remaining portion of one just fits into the notch in the other, so that the upper and under surfaces of the members are flush.

_No. 14. A cross-lap joint_, Fig. 264, is a halved joint in which both members project both ways from the joint. This is a very common joint used in both carpentry and joinery, as where stringers cross each other in the same plane.

The two pieces are first dressed exactly to the required size, either separately or by the method of making duplicate parts, see Chap. IX, p. 204. Lay one member, called X, across the other in the position which they are to occupy when finished and mark plainly their upper faces, which will be flush when the piece is finished. Locate the middle of the length of the lower piece, called Y, on one arris, and from this point lay off on this arris half the width of the upper piece, X. From this point square across Y with the knife and try-square. Lay X again in its place, exactly along the line just scored. Then mark with the knife on Y the width of X, which may then be removed and the second line squared across Y. From these two lines square across both edges of Y to approximately one-half the thickness.

Now turn X face down, lay Y on it, and mark it in the same way as Y.

Set the gage at one-half the thickness of the pieces, and gage between the lines on the edges, taking care to hold the head of the gage against the marked faces. Then even if one piece is gaged so as to be cut a little too deep, the other will be gaged so as to be cut proportionately less, and the joint will fit.

Cut a slight triangular groove on the waste side of the knife-marks, Fig. 91, p. 66, saw accurately to the gaged lines, and chisel out the waste as in a dado, see Figs. 70 and 71, p. 56.

The bottom of the dado thus cut should be flat so as to afford surface for gluing. When well made, a cross-lap joint does not need to be pounded together but will fit tight under pressure of the hands.

_No. 15. A middle-lap joint or halved tee_, Fig. 265, is made in the same way as a cross-lap joint, but one member projects from the joint in only one direction, it is used to join stretchers to rails as in floor timbers.

_No. 16. An end-lap joint_, Fig. 265, is made in the same way as a cross-lap joint except that the joint is at the end of both members.

It is used at the corners of sills and plates, also sometimes in chair-seats.

To make an end-lap joint, place the members in their relative positions, faces up, and mark plainly. Mark carefully on each member the inside corner, allowing the end of each member slightly (1/16") to overlap the other. Square across at these points with a sharp knife point, on the under side of the upper member, and on the upper side of the lower member. Now proceed as in the cross-lap joint, except that the gaged line runs around the end and the cutting must be done exactly to this line.

_No. 17._ In an _end-lap joint on rabbeted pieces_, Fig. 265, the joint must be adapted to the rabbet. The rabbet should therefore be plowed before the joint is made. The rabbet at the end of the piece X is cut not the entire width of the piece Y, but only the width of the lap,--c-f=a-e. This joint is used occasionally in picture-frames.