Scroll Sawing Machines

The scroll sawing machine derives its name from the fact that it is particularly fitted for sawing scroll or curved work by reason of the saw (which is a ribbon of steel with the teeth cut on one edge) being very narrow.

The principal points in a scroll sawing machine are to have the saw held under as nearly equal tension as possible throughout the whole of the stroke; to render the machine readily adjustable for different lengths or sizes of saws, to provide it with means of taking up lost motion, and to avoid vibration when the machine is at work.

A scroll sawing machine constructed by the Egan Company is shown in Fig. 3122, a sectional view of the saw straining mechanism being shown in Fig. 3123. a, a, is a casting having slides for the head b, which is adjustable upon a to suit different lengths of saws, and is secured in its adjusted position by the bolt c and nut d. To the ends of the springs s, a strip or band of leather is secured, the other end passing around the small step f of a roller r, and being secured thereto. The roller r is so supported that it may rise and fall with the strokes of the saw. A second leather band g is secured at t, passes over the large step of r, and at its lower end hooks to the saw, which is strained by the springs s. This reduces the motion of the springs, and thus serves to equalize their pressure throughout the saw stroke.

The lower end of the saw is gripped in a slide or cross-head that is driven by the connecting rod and crank motion shown in the general view Fig. 3122. The lever shown at the foot of the machine moves the belt to the fast or loose pulley to start or stop the machine, and operates a brake to stop the machine quickly.

Fig. 3124 represents a scroll saw constructed by H. L. Beach. This machine is provided with a tilting table, which can be set at any angle up to 39 degrees, either to the right or left, the exact angle being indicated by a graduated arc.

The straining device, including the springs, air pump, guide-ways, cross-head and steel bearing, are all attached to the vertical tubular shaft, which is secured to the heavy cast back support by the box e and eccentric lever f. By raising the lever f, the shaft, being balanced, is free to move up or down to suit any length of saw.

At the same time, the steel bearing l forms a support for the back and sides of the saw, and can be raised or lowered to suit any thickness of work.

The under guide-ways are so constructed that their expansion by tightening does not tighten the cross-head. Instead of the ordinary tight and loose pulleys, the crank shaft carries a friction pulley and combination brake by which the saw is stopped or started instantly, by a single motion of the foot.

This leaves the hands entirely free, and saves considerable time in stopping and starting.

The lower end of the saw is held by a steel clamp; when the saw breaks it can be used again by filing a notch. Both ends of the saw are arranged to take up lost motion and wear.

Any desired strain from 10 to 75 pounds can be given to the saw, and the strain is equal at all points of the stroke.