1. The Rule. The standard unit of length is the yard, but the foot is commonly used for all measurements in woodwork. If the rule be twelve inches long it is known as a foot rule, and if twenty-four inches long it is called a two-foot rule. The inches are subdivided into halves, quarters, eighths, and in some cases sixteenths. Rules are usually of boxwood or maple, with brass joints, and are commonly made to fold once or twice.
Fig. 1. The Rule
The rule is quite thick, and if laid flat upon the work to be measured errors will usually follow. It should be stood on edge so that the pencil or knife point may touch the divisions on it and the wood at the same time. The proper position when laying out measurements is shown in the sketch (Fig. 2). Consecutive measurements should be laid off without moving the rule.
Fig. 2. Methods of using the Rule: A, incorrect; B, correct
2. The Try-Square. The try-square has two distinct uses: first, to act as a guide for the pencil or knife point in laying out lines across the grain at right angles to the edge, as shown in Fig. 4; second, for testing or trying the adjoining sides to see if they are square with each other.
Fig. 3. The Try-Square
The try-square may be made entirely of iron or steel, but sometimes the beam A is of wood with a brass strip C to protect it and to take the wear. The blade B is of steel and is divided, like a rule, into inches and fractions of an inch. Try-squares are made in several sizes, the most convenient for general use being six inches.
Fig. 4. Methods of using the Try-Square
In using the try-square the beam should be held firmly against the face or edge of the stock. When working near the end of the piece, if the beam projects, reverse its position. For nice, accurate work the knife point instead of the pencil should be used for lining.
When it is desired to saw off the end of the stock it is first necessary to mark or square clear around it with the knife and try-square. In doing this the beam of the try-square must be used against the work face and joint edge only. Large squares made of steel in one piece are called framing squares, and are used by carpenters and others for rough or large work.
Fig. 5. The Framing Square
Fig. 6. The Marking Gauge
3. The Marking Gauge. The marking gauge is shown in Figs. 6 and 7. A is the gauge stick, B the gauge block, S the set screw, and P the marking point, or spur. The gauge stick is graduated like a rule into inches and fractions, beginning at the steel marking point; but as the latter is not always exactly in the right place the graduations are not entirely reliable. It is safer then to set the gauge with the rule in the manner shown in Fig. 7.
Hold gauge bottom side up in left hand and rule in right. Place end of rule against gauge block and the measurement desired at spur. Turn set screw. The gauge is then accurately set. In the cut the gauge is set at one inch and is ready for use.
Fig. 7. Setting the Marking Gauge
To gauge a line parallel to the edge of a block hold the tool firmly, with thumb and forefinger encircling gauge block. Tip the tool away from you until the marking point (spur) barely touches the wood and push the tool away from (never toward) you. The line made should be as fine as a knife line. A little practice is needed to give the proper control, as the marking point tends to follow the grain of the wood, which is usually not straight.
Fig. 8. Holding the Marking Gauge
A good plan is to use a small piece of prepared stock as a practice block, laying out lines a quarter of an inch apart, then an eighth, and finally a sixteenth.
4. The Bevel. The bevel differs from the try-square in having a movable blade.
Fig. 9. The Bevel
This tool may be used to lay out lines at any angle from zero to 180 degrees. The blade may be fixed firmly at any desired angle by simply turning the set screw. The method of using it is similar to that of the try-square.