helical-gear

// Helical Gear // A helical gear is a type of cylindrical gear where the teeth are slanted at an angle relative to the axis of rotation. This greatly reduces noise and wear when transmitting torque across meshed spinning gears  // Set units @settings(defaultLengthUnit = mm)  // Define a function to create a helical gear fn helicalGear(nTeeth, module, pressureAngle, helixAngle, gearHeight) {  // Calculate gear parameters  pitchDiameter = module * nTeeth  addendum = module  deddendum = 1.25 * module  baseDiameter = pitchDiameter * cos(pressureAngle)  tipDiameter = pitchDiameter + 2 * module   // Define the constants of the keyway and the bore hole  keywayWidth = 2  keywayDepth = keywayWidth / 2  holeDiam = 7  holeRadius = holeDiam / 2  startAngle = asin(keywayWidth / 2 / holeRadius)   // Sketch the keyway and center hole  holeWithKeyway = startSketchOn(XY)  |> startProfile(at = [  holeRadius * cos(startAngle),  holeRadius * sin(startAngle)  ])  |> xLine(length = keywayDepth)  |> yLine(length = -keywayWidth)  |> xLine(length = -keywayDepth)  |> arc(angleStart = -1 * startAngle + 360deg, angleEnd = 180deg, radius = holeRadius)  |> arc(angleStart = 180deg, angleEnd = startAngle, radius = holeRadius)  |> close()   // Define a function to create a rotated gear sketch on an offset plane  fn helicalGearSketch(offsetHeight) {  // Calculate the amount to rotate each planar sketch of the gear given the gear helix angle and total gear height  helixCalc = acos(offsetHeight * tan(helixAngle) / (tipDiameter / 2))   // Using the gear parameters, sketch an involute tooth spanning from the base diameter to the tip diameter  helicalGearSketch = startSketchOn(offsetPlane(XY, offset = offsetHeight))  |> startProfile(at = polar(angle = helixCalc, length = baseDiameter / 2))  |> involuteCircular(  startDiameter = baseDiameter,  endDiameter = tipDiameter,  angle = helixCalc,  tag = $seg01,  )  |> line(endAbsolute = polar(angle = 160deg / nTeeth + helixCalc, length = tipDiameter / 2))  |> involuteCircular(  startDiameter = baseDiameter,  endDiameter = tipDiameter,  angle = -(4 * atan(segEndY(seg01) / segEndX(seg01)) - (3 * helixCalc)),  reverse = true,  )   // Position the end line of the sketch at the start of the next tooth  |> line(endAbsolute = polar(angle = 360deg / nTeeth + helixCalc, length = baseDiameter / 2))   // Pattern the sketch about the center by the specified number of teeth, then close the sketch  |> patternCircular2d(  instances = nTeeth,  center = [0, 0],  arcDegrees = 360deg,  rotateDuplicates = true,  )  |> close()  |> subtract2d(tool = holeWithKeyway)  return helicalGearSketch  }   // Draw a gear sketch on the base plane  gearSketch001 = helicalGearSketch(offsetHeight = 0)   // Draw a rotated gear sketch on a middle interstitial plane  gearSketch002 = helicalGearSketch(offsetHeight = gearHeight / 2)   // Draw a rotated gear sketch at the gear height offset plane  gearSketch003 = helicalGearSketch(offsetHeight = gearHeight)   // Loft each rotated gear sketch together to form a helical gear  helicalGear = loft([  gearSketch001,  gearSketch002,  gearSketch003  ])   return helicalGear }  helicalGear(  nTeeth = 21,  module = 2,  pressureAngle = 20deg,  helixAngle = 35deg,  gearHeight = 7, )