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Continuous Rolling Cutter Shears. The shears shown in Fig. 118 are operated by a pinion lever engaging in a rack and cutting with the forward roll of the cutting disc.
The advantage of this construction is that the power travels with the cutter. With ordinary shears as the cutting edge recedes from the fulcrum the resistance increases, not so with these shears, the resistance and power being the same all along the cut.
The motion of the circular cutting disc is about onethird of its circumference. The cutting disc is provided with three slots, which correspond with three pins on the cutting disc bolt, this enables the operator to change the cutting disc to six different positions; three on each side, the disc being reversible.
The lower or stationary straight cutter blade has two cutting edges, the ends of the cutter are beveled to match the heads of the bolts which draw the cutter blade in recess of shear stock. Two set screws which press this cutter blade in opposite directions are the means to adjust the lower cutter perfectly to the upper cutter disc.
The angle of contact of the two cutters remains the same during action, therefore, this shear is well adapted to cut pieces out of a sheet of metal without injuring the same by cross-cut marks, which is very difficult with other shears.
The circular cutter on the front of the vertical plate of shear stock, and the pinion lever on the back, whose surfaces are perfectly parallel, when drawn up reasonably well by the nut of the bolt or shaft, bear so well against the plate that the friction of the two cutters can be totally obliterated by proper adjustment with the set screws in combination with the bevel head bolts, thus securing long service before any sharpening is necessary. This is the most simple shearing device for cutting sheet metal. It is especially adapted to tin and sheet metal workers.
metal. It may be used for cutting %-inch iron, and 3-16 and Vi-inch narrow bars. The machine will punch the center of a circle 5y± inches in diameter.
Shears for Cutting Circles or Rings. The machine shown in Fig. 120 is constructed so that it can be used either by hand or power. It is designed for cutting rings from a sheet of metal without cutting through the outer edge, that is, internal circles, it also can be used as a regular circular shears. It is made in one
size only, and will cut circles from 3 to 40 inches in diameter, and internal rings from 3 to 39 inches in diameter. It can be used on sheet metal as heavy as No. 16 gauge. The machine as constructed is adapted to run at about 80 revolutions per minute and is fitted with a pulley 10x3 for power, and a crank for hand use.
Combination Circular or Rotary Shears. The shears represented in Fig. 121 are made so they can be used by hand or power, but are without burring attachment. They have an adjusting screw, and a scale on the bed, so that a very accurate adjustment can be made.
Light Bending Rolls. Bending rollers are used much by sheet-metal workers. They are light by comparison with those employed by boilermakers, or from