Abstract: A hand-held circular saw designed for making square cuts on workpieces. The saw is equipped with a pair of retractable guide pins located near the rear of the blade; when both pins touch the front edge of the workpiece the saw's blade is automatically perpendicular to it. The saw is also equipped with at least one torsion spring that temporarily holds the saw's blade above the workpiece. Without moving the saw's base, the user turns on the saw, and pressing downwardly on its handle, lowers the blade into the workpiece, making a square cut with the accuracy of a cut-off saw. The guide pins can also be automatically or manually retracted to convert the improved saw back to a conventional saw.

Abstract: An improved hand-held circular saw having increased accuracy, speed and safety for square cuts on workpieces. The saw is equipped with a pair of retractable guide pins; when both pins touch the front edge of the workpiece the Saw's blade is automatically perpendicular to it. The saw is also equipped with at least one torsion spring that temporarily holds the saw's blade above the workpiece. Without moving the saw's base, the user turns on the saw, and pressing downwardly on its handle, lowers the blade into the workpiece, making a square cut with the accuracy of a cut-off saw. The guide pins can also be automatically or manually retracted to convert the improved saw back to a conventional saw.

Abstract: A microtome having a rotatable platform and a fixedly mounted cutting blade which is disposed perpendicularly to the axis of a shaft about which the platform rotates. With each rotation, it carries the specimen holder beneath the blade. The height of the cutting edge of the blade relative to a specimen mounted atop the holder determines the thickness of any section cut therefrom. After each cut, the holder can be automatically raised in height by a predetermined increment to allow another section of the same thickness to be cut. Mechanisms are also provided which eliminate play in both the radial and axial directions between a cylindrical housing supporting the platform and the shaft, so that the microtome can be used to make extremely precise cuts of specimens.

Abstract: A disposable blade holder for use with an apparatus, such as a microtome which is employed in cutting thin sections of tissue and other materials for microscope viewing. The blade holder is removably mountable in a microtome and secured therein by clamps. The holder comprises a cover plate and a base with a pair of small steps slightly greater in height than the thickness of a disposable blade. When a portion of the cover plate, disposed inwardly of the steps and otherwise suspended between them, is subjected to a sufficiently large force directed toward the base, the cover plate is deflected slightly and presses against the blade holding it firmly. The greatest deflection of the cover plate occurs in its mid-section so that the cover plate comes into contact with the blade first before it can touch the remainder of the base. The same clamps used to secure the blade holder itself to the microtome also serve to keep the cover pressed against the blade.