[CHAPTER XV]
THE FRET-SAW
The Fret-saw is a delightful tool, and very useful to the toy-maker. It can be used for making wheels and the various jointed and mechanical toys described in the following chapters.
In dealing with the fret-saw we have to consider (1) the saw-blades and (2) the frame in which they are held. The saw-blades are about five inches in length and are made of delicate steel wire with correspondingly fine teeth. They are very cheap, being commonly sold at about three halfpence to threepence a dozen, and even less when purchased by the gross. They are supplied in ten different grades, numbered from 00 to 8, proceeding from fine to coarse. For the toys described in this book, Nos. 1, 2 and 3 will be found most suitable. To preserve the saw-blades from rust, keep them in a wood or metal case. Upon the proper tension of the saw-blade depends its action. To keep it taut, a number of frames have been designed, the most practical being one made of steel and varying in size from 12 inches to 18 inches measuring from the saw-blade to the back of the frame. The handle is of wood. The 12-inch size is the most suitable for children.
Cheap frames can be obtained for sixpence halfpenny (smaller ones even for fourpence). In the cheaper kinds the necessary tension is obtained by drawing the arms slightly towards each other when clamping the blade. The spring of the steel will then keep the blade sufficiently taut. In the better-class frames (price from two shillings upward) the tension is secured by the action of a lever. Notice that the saws must be inserted with the teeth pointing downward.
Holding and managing the Saw-frame. The hand saw-frame requires all the steadiness possible; the bend of the frame should rest along the forearm, and against the shoulder if the frame be a long one, or under the shoulder if a short one. This prevents the frame from swinging round.
The saw-blade will describe the arc of a circle as it passes through the wood, and this dip is reduced to the minimum by making short strokes instead of long ones. This is important to remember. The amateur is sure to break a few saw-blades at first, they are so fragile, indeed even in the hands of an expert they have a precarious hold on life and can only be expected to last a certain time. Fortunately they are cheap.
The saw-blade must not be pressed on into the wood too quickly; the wood is held to the table with the fingers, and every part of the line to be cut is moved in due succession against the cutting edge of the blade. Excessive energy will often cause the blade to stick fast in the wood; in this case the blade must be eased by gently working it up and down so that it does not cut but frees itself. This method can be adopted when turning a sharp corner; work the saw up and down (without cutting) until the blade points in the right direction.
Very often the locking of the blade in the wood is due to gummy or heavy wood, or to a twist in the saw-blade; this latter cause can be prevented by the exercise of care in fixing the saw in the frame.
Children should have the cheaper frames to practise with; however they soon learn to manage them and in due course find out that a saw-blade is really not so delicate as it looks. In cutting out animals, etc., leave a piece of surplus wood round the frailer parts as long as possible so that one has something to hold without fear of breakage.
When an interior space has to be cut out (e.g. when cutting away interior portions of wheels to make the spokes) a hole must be made by means of the Archimedean drill to admit the saw; the upper end of the saw is released from its clamp, passed through the hole, and again fixed in position. The hole in all cases should be bored as near as possible to a corner or point, as these are convenient starting-places. A medium-sized drill point rather than fine points should be used wherever space permits. Fine points are apt to break. The drill stock must be held quite vertical and revolved both when the point is entering the wood and when it is being withdrawn. No pressure is required on the drill beyond its own weight.