| 摘要 |
A glass-breaking apparatus adapted for breaking microtome knives of the Ralph type, including a generally horizontal base having right and left upright posts which serve in the manner of vices or clamps. A rigid fulcrum in the form of a hardened and elongated member is fixed to the base at a central position between the two upright structures. A movable block is positioned at a desired location between the two upright posts in such a way that the block may affect the precise placement of a piece of glass in the apparatus-by virtue of pushing the glass rearwardly against the block. Index lines are provided on the vertical front face of the block, for use in manually aligning a score line on the top of the glass piece with a desired one of the index lines. The fulcrum is preferably removable and replaceable at will with a similar fulcrum of the same or a different length. Ideally, the fulcrum is selected so as to be significantly shorter than the width of the glass piece, so that there will be a minimum overhang of 1/8 of the glass width on each end of the fulcrum. When sufficient strain is thereafter imparted to the glass piece, it will fracture-beginning at the score line and traveling downward along a cleavage plane toward the fixed fulcrum. The intersection of the cleavage plane with the bottom surface of the glass produces a very sharp cutting edge.
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