Precision cutting tool

Claim 1

A precision cutting instrument of the type adapted for use by graphic artists, said cutting instrument comprising: an elongated handle having a longitudinal axis extending along the length thereof; a planar cutting blade having a cutting edge and a tang portion spaced therefrom; and clamping means mounted on one end of said handle for detachably clamping the tang portion of the blade to said one end of the handle to position said blade in one of a plurality of predetermined angular positions relative to said axis, said clamping means comprising: (a) a shaft for supporting said blade on said one end of the handle; (b) means for rotatably mounting said shaft on said one end of the handle; (c) means for keying said blade to said shaft so as to rotate therewith, whereby the angular position of said blade relative to said axis is governed by the angular position of said shaft; and (d) locking means for selectively preventing rotational movement of said shaft in at least one direction while said blade is positioned in one of said plurality off predetermined angular positions, said locking means comprising: (i) a disc-member having a plurality of spaced indentations formed in the periphery thereof, said disc being journalled to rotate with said shaft and being slidably mounted on said shaft for axial movement between first and second spaced positions; (ii) a pin member rigidly mounted on said one end of the handle and extending outwardly therefrom to engage one of said indentations while said disc is in said first position, and thereby prevent rotational movement of said shaft, said pin member being of a length shorter than the spacing between said first and second positions, whereby said pin member disengages said indentation upon movement of said disc to said second position, and thereby allows said shaft to rotate; and (iii) means for urging said disc into said first position.