bracket

// Shelf Bracket
// This is a bracket that holds a shelf. It is made of aluminum and is designed to hold a force of 300 lbs. The bracket is 6 inches wide and the force is applied at the end of the shelf, 12 inches from the wall. The bracket has a factor of safety of 1.2. The legs of the bracket are 5 inches and 2 inches long. The thickness of the bracket is calculated from the constraints provided.

// Set units
@settings(defaultLengthUnit = in)

// Define parameters
sigmaAllow = 35000 // psi (6061-T6 aluminum)
width = 5.0
p = 300 // Force on shelf - lbs
fos = 1.2 // Factor of safety of 1.2
shelfMountLength = 5.0
wallMountLength = 2.25
shelfDepth = 12 // Shelf is 12 inches deep from the wall
shelfMountingHoleDiameter = .50
wallMountingHoleDiameter = .625

// Calculated parameters
moment = shelfDepth * p // assume the force is applied at the end of the shelf
thickness = sqrt(moment * fos * 6 / (sigmaAllow * width)) // required thickness for two brackets to hold up the shelf
bendRadius = 0.25
extBendRadius = bendRadius + thickness
filletRadius = .5
shelfMountingHolePlacementOffset = shelfMountingHoleDiameter * 1.5
wallMountingHolePlacementOffset = wallMountingHoleDiameter * 1.5

// Add checks to ensure bracket is possible. These make sure that there is adequate distance between holes and edges.
assertGreaterThanOrEq(wallMountLength, wallMountingHoleDiameter * 3, "Holes not possible. Either decrease hole diameter or increase wallMountLength")
assertGreaterThanOrEq(shelfMountLength, shelfMountingHoleDiameter * 5.5, "wallMountLength must be longer for hole sizes to work. Either decrease mounting hole diameters or increase shelfMountLength")
assertGreaterThanOrEq(width, shelfMountingHoleDiameter * 5.5, "Holes not possible. Either decrease hole diameter or increase width")
assertGreaterThanOrEq(width, wallMountingHoleDiameter * 5.5, "Holes not possible. Either decrease hole diameter or increase width")

// Create the body of the bracket
bracketBody = startSketchOn(XZ)
  |> startProfileAt([0, 0], %)
  |> xLine(length = shelfMountLength - thickness, tag = $seg01)
  |> yLine(length = thickness, tag = $seg02)
  |> xLine(length = -shelfMountLength, tag = $seg03)
  |> yLine(length = -wallMountLength, tag = $seg04)
  |> xLine(length = thickness, tag = $seg05)
  |> line(endAbsolute = [profileStartX(%), profileStartY(%)], tag = $seg06)
  |> close()
  |> extrude(%, length = width)

// Add mounting holes to mount to the shelf
shelfMountingHoles = startSketchOn(bracketBody, face = seg03)
  |> circle(
       center = [
         -(bendRadius + shelfMountingHolePlacementOffset),
         shelfMountingHolePlacementOffset
       ],
       radius = shelfMountingHoleDiameter / 2,
     )
  |> patternLinear2d(instances = 2, distance = -(extBendRadius + shelfMountingHolePlacementOffset) + shelfMountLength - shelfMountingHolePlacementOffset, axis = [-1, 0])
  |> patternLinear2d(instances = 2, distance = width - (shelfMountingHolePlacementOffset * 2), axis = [0, 1])
  |> extrude(%, length = -thickness - .01)

// Add mounting holes to mount to the wall
wallMountingHoles = startSketchOn(bracketBody, face = seg04)
  |> circle(
       center = [
         wallMountLength - wallMountingHolePlacementOffset - bendRadius,
         wallMountingHolePlacementOffset
       ],
       radius = wallMountingHoleDiameter / 2,
     )
  |> patternLinear2d(instances = 2, distance = width - (wallMountingHolePlacementOffset * 2), axis = [0, 1])
  |> extrude(%, length = -thickness - 0.1)

// Apply bends
fillet(bracketBody, radius = extBendRadius, tags = [getNextAdjacentEdge(seg03)])
fillet(bracketBody, radius = bendRadius, tags = [getNextAdjacentEdge(seg06)])

// Apply corner fillets
fillet(
  bracketBody,
  radius = filletRadius,
  tags = [
    seg02,
    getOppositeEdge(seg02),
    seg05,
    getOppositeEdge(seg05)
  ],
)