gears

thingiverse

//make in https://openjscad.org/ function main(params) { var dist = (params.numTeeth*params.circularPitch/8.28) +(params.numTeeth2*params.circularPitch2/8.28); // Main entry point; here we construct our solid: var gear = Gear(params).translate([dist,dist,0]); params.numTeeth = params.numTeeth2; params.circularPitch = params.circularPitch2; params.pressureAngle = params.pressureAngle2; params.clearance = params.clearance2; params.thickness = params.thickness2; gear = union(gear,Gear(params)); return gear; } function Gear(params) { // Main entry point; here we construct our solid: var gear = involuteGear( params.numTeeth, params.circularPitch, params.pressureAngle, params.clearance, params.thickness ); if(params.centerholeradius > 0) { var centerhole = CSG.cylinder({start: [0,0,-params.thickness], end: [0,0,params.thickness], radius: params.centerholeradius, resolution: 16}); gear = gear.subtract(centerhole); } return gear; } // Here we define the user editable parameters: function getParameterDefinitions() { return [ { name: 'numTeeth', caption: 'Number of teeth:', type: 'int', default: 15 }, { name: 'circularPitch', caption: 'Circular pitch:', type: 'float', default: 10 }, { name: 'pressureAngle', caption: 'Pressure angle:', type: 'float', default: 20 }, { name: 'clearance', caption: 'Clearance:', type: 'float', default: 0 }, { name: 'thickness', caption: 'Thickness:', type: 'float', default: 5 }, { name: 'centerholeradius', caption: 'Radius of center hole (0 for no hole):', type: 'float', default: 2 }, { name: 'numTeeth2', caption: 'Number of teeth2:', type: 'int', default: 15 }, { name: 'circularPitch2', caption: 'Circular pitch2:', type: 'float', default: 10 }, { name: 'pressureAngle2', caption: 'Pressure angle2:', type: 'float', default: 20 }, { name: 'clearance2', caption: 'Clearance2:', type: 'float', default: 0 }, { name: 'thickness2', caption: 'Thickness2:', type: 'float', default: 5 }, { name: 'centerholeradius2', caption: 'Radius of center hole (0 for no hole):', type: 'float', default: 2 }, ]; } /* For gear terminology see: http://www.astronomiainumbria.org/advanced_internet_files/meccanica/easyweb.easynet.co.uk/_chrish/geardata.htm Algorithm based on: http://www.cartertools.com/involute.html circularPitch: The distance between adjacent teeth measured at the pitch circle */ function involuteGear(numTeeth, circularPitch, pressureAngle, clearance, thickness) { // default values: if(arguments.length < 3) pressureAngle = 20; if(arguments.length < 4) clearance = 0; if(arguments.length < 4) thickness = 1; var addendum = circularPitch / Math.PI; var dedendum = addendum + clearance; // radiuses of the 4 circles: var pitchRadius = numTeeth * circularPitch / (2 * Math.PI); var baseRadius = pitchRadius * Math.cos(Math.PI * pressureAngle / 180); var outerRadius = pitchRadius + addendum; var rootRadius = pitchRadius - dedendum; var maxtanlength = Math.sqrt(outerRadius*outerRadius - baseRadius*baseRadius); var maxangle = maxtanlength / baseRadius; var tl_at_pitchcircle = Math.sqrt(pitchRadius*pitchRadius - baseRadius*baseRadius); var angle_at_pitchcircle = tl_at_pitchcircle / baseRadius; var diffangle = angle_at_pitchcircle - Math.atan(angle_at_pitchcircle); var angularToothWidthAtBase = Math.PI / numTeeth + 2*diffangle; // build a single 2d tooth in the 'points' array: var resolution = 5; var points = [new CSG.Vector2D(0,0)]; for(var i = 0; i <= resolution; i++) { // first side of the tooth: var angle = maxangle * i / resolution; var tanlength = angle * baseRadius; var radvector = CSG.Vector2D.fromAngle(angle); var tanvector = radvector.normal(); var p = radvector.times(baseRadius).plus(tanvector.times(tanlength)); points[i+1] = p; // opposite side of the tooth: radvector = CSG.Vector2D.fromAngle(angularToothWidthAtBase - angle); tanvector = radvector.normal().negated(); p = radvector.times(baseRadius).plus(tanvector.times(tanlength)); points[2 * resolution + 2 - i] = p; } // create the polygon and extrude into 3D: var tooth3d = new CSG.Polygon2D(points).extrude({offset: [0, 0, thickness]}); var allteeth = new CSG(); for(var i = 0; i < numTeeth; i++) { var angle = i*360/numTeeth; var rotatedtooth = tooth3d.rotateZ(angle); allteeth = allteeth.unionForNonIntersecting(rotatedtooth); } // build the root circle: points = []; var toothAngle = 2 * Math.PI / numTeeth; var toothCenterAngle = 0.5 * angularToothWidthAtBase; for(var i = 0; i < numTeeth; i++) { var angle = toothCenterAngle + i * toothAngle; var p = CSG.Vector2D.fromAngle(angle).times(rootRadius); points.push(p); } // create the polygon and extrude into 3D: var rootcircle = new CSG.Polygon2D(points).extrude({offset: [0, 0, thickness]}); var result = rootcircle.union(allteeth); // center at origin: //result = result.translate([0, 0, -thickness/2]); return result; }