For dressing the edges of planks parallel and to width what are called gang edgers or gang edging machines are employed.
A gang edger consists of an arbor driving two or more circular saws, through which the boards to be edged are fed. Means are provided whereby the distance apart of the saws may be rapidly adjusted while the saws are in motion, so that if a board will not true up to a given width, the saws may be set to cut it to a less one without delay.
Fig. 3109.
[Fig. 3109] represents a self-feeding gang edger, constructed by J. A. Fay & Company, and in which the left-hand saw may be fixed at any required position on the left-hand half of the saw arbor, while the two right-hand ones may be adjusted independently along the arbor, while the machine is running.
At the back of the saw is a feed roll, and above it a pressure roll, whose pressure may be regulated by means of the weight and bar shown at the back of the machine. The object of placing the feed and pressure rolls at the back of the saws, is, that if a board is found to be too narrow for the adjustment of the saws, it may be withdrawn without stopping or reversing the machine, and the saws may be drawn together sufficiently to suit the case.
[Fig. 3110] is a plan and [Fig. 3111] an edge view of the work table, and show the means of adjusting the saws. a is the saw arbor, and 1, 2, 3, the circular saws. Saw 1 is carried by the sleeve b, which is secured in its adjusted position by the set screw c.
