1. The Rule.—The foot is used as a unit of measurement in woodwork. The rule ordinarily used is called a two-foot rule because of its length. Such rules are hinged so as to fold once or twice and are usually made of boxwood or maple.
The divisions along the outer edges, the edges opposite the center hinge, are inches, halves, fourths, eighths, and on one side sixteenths also. Fig. 1.
The rule should not be laid flat on the surface to be measured but should be stood on edge so that the knife point can be made to touch the divisions on. the rule and the Fig. 2.
Whenever there are several measurements to be made along a straight line, the rule should not be raised until all are made, for with each placing of the rule errors are likely to occur.
The rule is used to find the middle of an edge or surface by placing it across the piece so that the distances from the edges of the piece to corresponding inch, or fractional marks, shall be the same, Fig. 3A, the middle of the piece being at a point midway between the marks selected.
Fig. 3B illustrates a second method of finding the middle of a piece. Lay the rule across the piece at an angle such that two of the unit marks shall rest each upon an arris. The middle of the piece will then be at that unit mark which is midway between these.
If it is desired to divide a piece into more than two parts lay the rule across the piece at such an angle as will bring two of its unit marks each upon an arris with the required number of divisions between. Fig. 3C shows a piece divided into three equal parts.
2. The Try-square.—The try-square may be made entirely of iron or steel or it may have a head of wood, called the beam, and a blade of steel. The blade is graduated into inches and fractions of an inch. As all try-squares are liable to be injured by rough usage, care should be taken not to let them drop on the bench or floor, nor should they ever be used for prying or pounding. Fig. 4.
The try-square is used for three purposes: First, to act as a guide
for the pencil or knife point in laying out lines across the grain at right angles to an edge or surface; second, to test an edge or end to see whether it is square to an adjoining surface or edge; third, to test a piece of work to see whether it is of the same width or thickness thruout its entire length.
Fig. 5 shows the various positions assumed in lining across a piece. The beam should be held firmly against either the face side or the face edge.
The face side of a piece is the broad surface which is first made true. The face edge is the first edge which is made square to the face side and straight. These two surfaces are usually marked in some way so that they may be distinguished from the other surfaces. Their use is fully explained in Chapter III.
If the beam projects beyond the end of the wood, it should be reversed. The knife should be inclined forward and away from the blade of the try-square slightly. A light, firm line should be made the first time across the piece.
In testing edges or ends for squareness, the beam should be held, as in lining, firmly either against the face side or the face edge. Fig. 6. Care should be taken to test the extreme ends of the piece.
Also test at a sufficient number of points to show fully the condition of the edge. Sliding the try-square along the edge is net objectionable if the blade be held lightly on the surface.
Under no circumstances should the try-square be used to scrape the wood.
In testing a piece to see whether it is of the same width or thickness thruout its entire length, place the blade across the surface to be tested, holding the beam lightly against the face side or face edge, slide the try-square along the piece with the eye fixed upon the graduations at the outer edge. Fig. 7.
3. The Framing Square.—Large squares of one piece of steel, called framing squares, are used by carpenters for large and rough work. The long arm is called the blade and the short one the tongue. In addition to the divisions into inches and fractions of an inch, there is on the blade a board measure table and on the tongue a brace or rafter measure table. This square will be found convenient when "catting up" stock, also for testing corners of large pieces of furniture and for setting the bevel to various angles.
4. The Bevel.—The bevel differs from the try-square in having a movable blade. Fig. 9. This blade may be set at any desired angle from 0 to 180 degrees. The manner of using the bevel is similar to that of the try-square. When adjusting, the blade should be just loose enough to move upon the application of slight pressure.
There are various ways of. setting the bevel to the required angle. Should the triangle used in mechanical drawing be available, angles of 30 degrees, 45 degrees and 60 degrees are easily obtained by adjusting the bevel to the sides of the required angle.
To set the bevel to 45 degrees by means of the framing square, hold the beam against one of the arms, Fig. 10, and move the blade so that it shall pass through corresponding points on both blade and tongue. Fig. 11 illustrates a method in which no other tools are needed. A line is squared across a board having a straight edge.
Equal distances are measured from the point at which the line cuts the edge, the blade then being made to pass thru these points while the beam is held tightly against the edge.
For angles of 30 degrees and 60 degrees, square a knife line at right angles to an edge. Fig. 12. Measure from the edge, along this line, or from this line along the edge any given distance.
Take twice this distance upon the blade of the bevel and adjust so
that a right triangle is formed in which the length of the longest side shall be twice that of the shortest.
5. The Marking Gage.—The gage is used for laying out lines along the grain of the wood. It consists of a beam, Fig. 13, head, thumbscrew, and marking point or spur.
The spur should be sharpened to a knife point with a file so that it may make a fine smooth line. It should project far enough below the beam so that the beam may be rolled forward in such a way as to bring the spur into the board at a slight angle, when properly marking. It should extend not less than an eighth of an inch and in most cases three-sixteenths of an inch.
The graduations on the beam are seldom reliable. It is safer to set the gage with the rule by measuring the distance from the spur to the gage block. This is done by holding the gage bottom side up in the left hand. With the right place the end of the rule against the head. Fig. 13.. After the screw has been tightened, apply the rule again to make sure of the correctness of the setting. To gage the line, take the tool in the right hand, three fingers grasping the beam, the first finger encircling the head, if the work is narrow, and the thumb back, or nearly back, of the spur. Fig. 14. The head should be kept against one or the other of the faces. Begin at the end of the piece which is towards you, hold the block firmly against the piece, roll the beam forward until the spur barely touches the surface, and make a very light line. Fig. 15 illustrates the manner of raising the spur from the wood by raising the wrist during the backward stroke. It will be found convenient to hold the piece against the bench stop. This steadies the piece and permits the worker to see how deep the spur is cutting and whether the head is against the face properly. Avoid deep lines; they are inaccurate even if straight and always cause trouble in the making unless the grain of the wood is perfectly straight.
6. The Pencil Gage.—There are occasions when a pencil gage marks with sufficient accuracy and is more suitable because its point does not cut the wood, as in gaging for a bevel. A hole bored thru the beam near one end, just large enough to receive a pencil snugly, will suffice. Fig. 16.
Fig 17 illustrates a method frequently used by carpenters. The fingers act as a gage head.
7. Slitting Gage.—A slitting gage is one in which the spur is sharp and strong, and will cut thru soft lumber as thick as one-quarter of an inch. The boards are cut from each side and considerable pressure is required. Sometimes a handle like that of the plane is fastened to the beam near the knife or spur.
8. The Mortise Gage.—Fig. 18 also shows a mortise gage used in advanced work. It has two spurs, one of them adjusted by means of the screw at the end of the beam to any desired distance from the stationary one, so that the two sides of a mortise or tenon can be marked at once.
9. The Dividers.—Dividers, Fig. 19, are used (1) in describing circles, (2) in dividing a given space into given number of parts, and (3) in marking one member which is to be fitted to another irregular member. Fig. 20 shows the manner of setting the dividers.
The thumbscrew should be released so that the legs may be moved without much effort. When the approximate setting has been secured, use the thumb-nut for adjusting to more accurate measurement. In describing circles, the dividers should be held as in Fig. 21 and swung to the right or left as is convenient. They should be leaned forward slightly and an effort made to secure a sharp, light line. For most work the two legs may be sharpened to points. Sometimes one is sharpened like a knife point.
10. Pencil and Knife.—Pencil lines may be used in getting out stock from rough material and in laying out work on rough surfaces where a knife line would not be visible. Pencil lines should be carefully made, however. The pencil may be used also in marking bevels, curves, and in other places where the knife or gage mark would be injurious. Otherwise, the knife and gage should be used. Pencil lines are easiest removed from wood by means of the eraser.
In laying out rough stock, if the first edge is sufficiently straight, it is usual to thumb-gage for width. This is 'done by holding the pencil at the end of the rule and using the thumb of the left hand as the gage-head, drawing the whole towards you with the rule acting as gage-beam.
A straight-edge, a board with a straight edge, is often used in marking out. Mark off the length of the piece of wood required. Mark off the breadth at the end of the board, also mark it near what is to be the other end of the piece. Place the straight-edge on these two marks and draw the line. Fig. 23. The try-square should be used to mark across the grain. Rip-saw first, then crosscut, leaving on the board all but just what is wanted for present use.