These are made somewhat like the squares, but with the exception that the blades are attached to the stock by a pin which permits of their being set at any angle other than a right angle, and held in such position by a thumbscrew; they are used for the purpose of marking lines at such angles to the first side of the piece of work. In some forms the blade is slotted through a part of its length and is called a "sliding" bevel. Others such as the "boat-builder's" bevels have two brass blades, one at each end of the stock, while in the "pro tractor" bevels the sliding arm works through a semi-circle graduated into degrees.
This is a device for guiding a saw so that it will cut at some regular angle, as 45 degrees. In its simplest form it is a rectan gular box composed of two vertical sides fastened to the bottom. A saw-cut made at an angle of 45 degrees through the sides guides the saw when it is employed to cut a piece of wood such as a picture molding placed in the mitre-box. Other cuts than those at an angle of 45 degrees may be made in the same box by cutting the guiding cuts at the required angles through the sides of the box. The most convenient form of mitre-box for cutting a wide series of angles is one provided with movable guides which may be readily set at the required angles. As a rule, the mitre edges of the moldings are left rough from the saw so as to make the glue adhere more firmly, but where sawed mitre-work requires to be planed smooth it is planed up with a "shooting board" which consists of two pieces of wood screwed together so as to form a step, on the upper one of which two strips of wood are screwed at right angles to each other. These strips act as guide-bars against which the piece of molding to be mitred is held and then planed off on the edge of the step.
Compasses and Calipers.— These devices are made of metal and are employed for the purpose of taking dimensions such as the in side and outside diameters of pipes and other cylindrical work that cannot be taken accu rately with a rule. A compass consists of two legs which are movable about a sector joint. In the form called a "wing-compass," it is pro vided with a metal arc and a set-screw attach ment which permits of its being set to corre spond with a definite measurement and remain so set without variation until that particular measurement is no longer required. Compasses
are also used for striking-out circular figures.
Calipers are termed "inside" and "outside" calipers according to the character of the dimen sions taken by their aid. Inside calipers are made with straight legs which are bent around only at the point and are used for measuring internal diameters. Outside calipers are made with bowed legs and are used for taking meas urements of external diameters. "Combination" calipers are an improved form in which the legs are pivoted near the middle point, thus making four movable ends, two of which are bowed and are used for taking outside measurements, and the other two straight and applicable to the taking of inside measurements.
These are appliances in the form of beam-compasses in which the heads slide along a straight bar to which they may be tightened by set-screws. The heads are made either of brass or of hard wood, the former i being preferable, and steel points are inserted into the bodies. They are employed for the purpose of taking measurements and for strik ing arcs which exceed the capacity of the ordinary compasses.
and The caliper-rule consists of a short steel rule, a portion of which is attached to a closely-fitting slide which may be drawn out until the object to be measured is embraced between the oppos ing portions of the rule. As both the rule and the slide are graduated into minute fractions of an inch, the thicknesses of the objects meas ured can be read off directly from the dimen sions on the slide. The caliper-square is a square, one elbow of which is fitted with a caliper-rule.
Bell This is a useful little device, by the aid of which a square, round, oval or triangular article may be instantaneously and accurately centred for the purposes of drilling and turning. It consists of a punch which is enclosed within a tube the lower end of which is expanded or tapered into the shape of a bell. This tapering mouth adapts itself to bars of different diameters, and when dropped over the end of a bar of any cross-section what ever ensures the marking of the exact centre of the bar by the point of the punch.
The holding tools are represented by the various forms of pincers, vises and clamps.