# US 4,397,207 A · Sheet metal cutting device for arcs and circles > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,397,207 A - Document ID: US4397207A - Status: Granted - Kind: A - Application number: 06/211,700 - Filed: 1980-12-01 - Granted: 1983-08-09 - Earliest claimed: 1980-02-25 - Inventors: Dalton Isaac - Web page: https://patentgrep.com/patent/US4397207A ## CPC - B23D 19/08: for special use, e.g. for cutting curves, for chamfering edges - B23D 33/04: for making circular cuts - Y10T 83/68: Entirely work supported - Y10T 83/7788: Tool carrier oscillated or rotated - Y10T 83/7797: Including means to rotate both elements of tool pair - B23D: PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR (making toothed gears or the like B23F; cutting metal by applying heat locally B23K; arrangements for copying or controlling B23Q) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A self-contained sheet metal cutter is mounted on a wheeled dolly and includes upper and lower power driven shear cutting wheels between which is engaged the plate or sheet to be cut. An adjustable trammel assembly extends from the dolly and includes a center point member engageable with an aperture in the plate to be cut and which corresponds to the center of the arc or circle. The trammel is adjustable to the radius of the arc or circle and the center point is engaged with the aperture in the sheet whereupon the wheeled dolly is pushed manually around the arc or circle as the shear wheels cut the sheet to the preset radius arc or circle. The rear wheel of the dolly is castor so that it follows the track readily and easily. ## Claims ### Claim 1 An arc or circle cutter for sheet metal and including a supporting surface for supporting at least part of the sheet being cut; comprising in combination a ground engaging wheeled dolly situated in a plane spaced below and outboard of said supporting surface, supporting structure supported on said dolly including a base, an adjustable trammel assembly extending from said supporting structure and engageable with the sheet at the centre of the arc or radius being cut, upper and lower shear cutter assemblies mounted upon said supporting structure for cutting action upon said sheet being cut, means to drive said cutter assemblies, and means to adjust the height of said upper and lower shear cutter assemblies relative to said dolly, said last mentioned means including a pair of supporting pillars secured to and extending upwardly from said base, a central pillar mounted for vertical movement between said support pillars, guide rollers cooperating between said support pillars and said central pillar and jack means on said base operatively connected to said central pillar to raise and lower said central pillar relative to said support pillars, a table mounted on said central pillar, said table and said upper and lower shear cutter assemblies being supported upon said central pillar and being raised and lowered therewith. ### Claim 2 (depends on 1) The invention according to claim 1 in which each of said shear cutter assemblies includes a shaft journalled for rotation in said supporting structure one above and one below said table, and a shear cutter wheel mounted upon each of said shafts, said shear cutter wheels overlapping one another adjacent the meeting peripheries thereof and being situated in side by side relationship to form a cutting jaw assembly, said means to drive said wheel cutters moving the overlapping portions thereof in the same direction. ### Claim 3 (depends on 1) The invention according to claim 1 in which said table includes a lower inner portion and an upper outer portion, said upper shear cutter assembly being mounted upon said upper outer portion, said lower shear cutter assembly being mounted below said lower inner portion, said lower inner portion supporting the curved part of the sheet being cut, the portion of said sheet being separated from said curved part of said sheet, passing under said upper outer portion. ### Claim 4 (depends on 2) The invention according to claim 2 in which said table includes a lower inner portion and an upper outer portion, said upper shear cutter assembly being mounted upon said upper outer portion, said lower shear cutter assembly being mounted below said lower inner portion, said lower inner portion supporting the curved part of the sheet being cut, the portion of said sheet being separated from said curved part of said sheet, passing under said upper outer portion. ### Claim 5 (depends on 1) The invention according to claim 1 in which said lower shear cutter assembly includes a support roller assembly adjacent thereto, said support roller assembly supporting the underside of the portion of said sheet being severed by said shear cutter assemblies, said upper shear cutter assembly including a pressure roller assembly, said pressure roller assembly bearing upon the upper surface of the portion of the sheet inboard of said dolly, each said support roller assembly and said pressure roller assembly including a mounting bar, a pair of rollers journalled for rotation thereon, and means to adjust the relationship of said roller assemblies relative to one another. ### Claim 6 (depends on 2) The invention according to claim 2 in which said lower shear cutter assembly includes a support roller assembly adjacent said shear cutter wheel, said support roller assembly supporting the underside of the portion of the sheet being severed by the shear cutter wheel, said upper shear cutter assembly including a pressure roller assembly adjacent said shear cutter wheel, said pressure roller assembly bearing upon the upper surface of the portion of the sheet inboard of said dolly, each said support roller assembly and said pressure roller assembly including a mounting bar, a pair of rollers journalled for rotation thereon one upon each side of the axis of said shear cutter wheel, and means to adjust the relationship of said roller assembly relative to one another. ### Claim 7 (depends on 3) The invention according to claim 3 in which said lower shear cutter assembly includes a support roller assembly adjacent thereto, said support roller assembly supporting the underside of the portion of said sheet being severed by said shear cutter assemblies, said upper shear cutter assembly including a pressure roller assembly, said pressure roller assembly bearing upon the upper surface of the portion of the sheet inboard of said dolly, each said support roller assembly and said pressure roller assembly including a mounting bar, a pair of rollers journalled for rotation thereon, and means to adjust the relationship of said roller assemblies relative to one another. ### Claim 8 (depends on 4) The invention according to claim 4 in which said lower shear cutter assembly includes a support roller assembly adjacent said shear cutter wheel, said support roller assembly supporting the underside of the portion of the sheet being severed by the shear cutter wheel, said upper shear cutter assembly including a pressure roller assembly adjacent said shear cutter wheel, said pressure roller assembly bearing upon the upper surface of the portion of the sheet inboard of said dolly, each said support roller assembly and said pressure roller assembly including a mounting bar, a pair of rollers journalled for rotation thereon one upon each side of the axis of said shear cutter wheel, and means to adjust the relationship of said roller assembly relative to one another. ### Claim 9 (depends on 1, 2, 3) The invention according to claims 1, 2 or 3 in which said trammel assembly includes an adjustable boom component pivotally supported by the inner end thereof upon said supporting structure and movable in a vertical plane from a sheet engaging position to a raised position and vice versa, means to raise and lower said boom component, over centre means cooperating with said last mentioned means to detachably lock said boom component in the raised position and a centre pivot component on the distal end of said boom component engageable with said sheet at the centre of the arc or circle being cut. ### Claim 10 (depends on 4, 5, 6) The invention according to claims 4, 5 or 6 in which said trammel assembly includes an adjustable boom component pivotally supported by the inner end thereof upon said supporting structure and movable in a vertical plane from a sheet engaging position to a raised position and vice versa, means to raise and lower said boom component, over centre means cooperating with said last mentioned means to detachably lock said boom component in the raised position and a centre pivot component on the distal end of said boom component engageable with said sheet at the centre of the arc or circle being cut. ### Claim 11 (depends on 7, 8) The invention according to claims 7 or 8 in which said trammel assembly includes an adjustable boom component pivotally supported by the inner end thereof upon said supporting structure and movable in a vertical plane from a sheet engaging position to a raised position and vice versa, means to raise and lower said boom component, over centre means cooperating with said last mentioned means to detachably lock said boom component in the raised position and a centre pivot component on the distal end of said boom component engageable with said sheet at the centre of the arc or circle being cut.