Abstract: A plotting board includes a base; a top; a pivot that connects the top and the base, the top and the base being rotatable and detachable with respect to each other, the pivot including a magnet wherein at least a portion of the pivot is disposed at a substantially central point on the top.

Abstract: A cutting mat comprises: a baseboard defined with an assembling hole and at least one notch on a side of the assembling hole, a positioning member detachably disposed in the assembling hole, and a cutting board. The positioning member includes a circular body and at least one positioning protrusion formed on a side of the circular body and located in a corresponding position to the notch of the baseboard. The cutting board is formed at the bottom thereof with a circular recess for engaging the circular body of the positioning member, so that the cutting board is rotatably superposed on the baseboard.

Abstract: A measuring device for measuring the arc of an arched window comprising a base; measuring means selectively rotatable relative said base for measuring a distance between said base and said arch at a selected angle.

Abstract: According to the present invention there is provided a protractor including a main body surrounding a circular aperture and having a scale of angular measurements thereon, and a rotary cursor mounted on the main body for rotary movement about the center of the circle of the circular aperture. The rotary cursor includes a part-circular center portion engaged in the circular aperture and rotatable within the aperture, and a radial arm portion extending radially outwardly from the center portion to the scale. The center portion of the rotary cursor is generally in the shape of a sector of a circular disc bounded by the reference side edge and the further side edge, and extends through about three quarters of a circle. The arm portion and the center portion of the cursor are formed as an integral unit.

Abstract: A protractor including a base having a curved surface formed in an upper portion, a disc including a circular outer peripheral surface for slidable engagement with the curved surface of the base, the disc including an opening, a pair of flanges formed in parallel in the opening, and a slide including two end portions slidably engaged with the flanges of the disc so that the slide can be guided to slide along the flanges, whereby various geometric figures can be drawn by the protractor when the disc rotates relative to the base and when the slide slides along the flanges.

Abstract: A plotting and drafting apparatus comprises a drawing implement having a body, a rule portion and a device for connecting the rule portion to the body. The body has a first surface and a first generating device for generating a first series of juxtaposed parallel linear magnetic poles in the first surface. The poles of the first series extend linearly in a first direction of parallelism with adjacent poles being spaced apart laterally from each other in a first direction normal to the first direction of parallelism. The rule portion has a datum edge disposed at an angle relative to the first direction of parallelism. The apparatus further includes a supporting device having a second surface for supporting the drawing implement and has a second generating device for generating a second series of juxtaposed parallel linear magnetic poles in the second surface.

Abstract: A rotatable drafting table includes a flat base board; a top drafting board position on top of the flat base board, the drafting board having a substantially rectangular configuration with slightly rounded corners; a swivel arrangement secured to the base board and drafting board for rotatably securing the drafting board on the base board; the base board having slide extensions at two front corners thereof; four pins provided at the free ends of the slide extensions and the opposite two corners of the base boards; a wire secured around the four pins; a parallel slide slideably mounted on the wire and positioned above the drafting board; and a braking assembly including at least one rubber brake pad secured at an underside of the drafting board for movement into braking contact with the upper surface of the base board.

Abstract: A rotatable drafting table includes a flat base board; a top drafting board position on top of the flat base board, the drafting board having a substantially rectangular configuration with slightly rounded corners; a swivel arrangement secured to the base board and drafting board for rotatably securing the drafting board on the base board; the base board having slide extensions at two front corners thereof; four pins provided at the free ends of the slide extensions and the opposite two corners of the base board; a wire secured around the four pins; a parallel slide slideably mounted on the wire and positioned above the drafting board; and a braking assembly including at least one rubber brake pad secured at an underside of the drafting board for movement into braking contact with the upper surface of the base board.

Abstract: A device for facilitating patent drafting comprises a base sheet, and a second sheet to which the drafting medium is affixed, the sheets having magnetic properties to maintain the base and second sheets in an alignable relationship with each other, the second sheet being transparent in some areas. Guidelines on the base and second sheets permit ready alignment of patent drafting requirements and to commonly used drafting angles. In one embodiment, the magnetic means are positioned to cause the sheets to maintain alignment at commonly used drafting angles.

Abstract: A navigational aid device of the type comprising a disc supporting a map, especially a chart, a protractor being movable over said map, a first carrier movable in the longitudinal direction of said disc, and a second carrier which is movable on said first carrier and in the transversal direction of said disc and upon which said protractor is rotatably journalled. Said first carrier consists of at least one ruler extending across said disc and situated upon said map and sliding means situated between said map and said disc and connected to said at least one ruler, said sliding means being provided with at least one guide member movable along track means provided on and extending longitudinally of said disc.

Abstract: A board has indexed tracks along each side with parallel transverse bars having end feet riding in the tracks and a marker being laterally adjustable between successive like separated positions along the bars for setting a marking position on a sheet of paper mounted on the board by releasable retaining means to identify to a blind person the end of ruling or marking upon the paper. A disc is also mountable for rotation and angular indexing on the board with a crosspiece adapted to slide in the tracks carrying a rotatable arm with marking means adjustably positioned thereon for drawing circles and rectangles on paper mounted on the board.

Abstract: A drawing apparatus includes a base member of rectangular form with front, rear and opposite side margins and an upper surface with a compass rose plate for affixing a drawing sheet thereon and pivotally mounted to the base member upper surface. A carriage frame is positioned generally on the upper surface of the base member and has spaced guide members slidably mounted to the base member side margins and interconnected by a crossbar for coordinated translatory movement. A parallel rule structure is supported by the carriage frame and has first and second drawing bars and first and second links forming an expansible and contractible parallelogram generally positioned atop the compass rose plate. The links are respectively mounted to the spaced guide members of the carriage frame for sliding movement therewith over the compass rose plate and for positioning the parallelogram rule structure at selected locations thereon.

Abstract: A fixture for providing positive control over a workpiece as it is being acted upon by a cutting or finishing tool. A base having a flat working surface is provided with a fixed guide member having a contoured control surface formed along the periphery thereof. A workholder is slidably supported upon the working surface of the base and is arranged to move in abutting contact against the control surface of the guide whereby a prescribed motion is imparted to a workpiece supported in the holder. In one form of the invention, the workholder is mounted upon a turntable that is rotatably supported in a circular guide whereby the work is caused to rotate about a fixed axis.