D.1 Three arm bracket

This is the shape from Solidworks Model Mania 2020. I had to make some adjustments to the model to make it work. The largest difference is that the cutout in each arm does end 1 mm before reaching the cylindrical part in the middle.

The model files can be found here: https://blogs.solidworks.com/tech/wp-content/uploads/sites/4/Model-Mania-2020-Phase1-drawing.png https://blogs.solidworks.com/tech/wp-content/uploads/sites/4/Model-Mania-2020-Phase2-drawing.png

As usual the fillets posed the biggest challenge. I solved this by rounding the cutout first before subtracting it from the main shape. Furthermore I cut the holes after filleting the shape to avoid the need to select the edges explicitly.

The code below contains some failed fillet experiments. The red shape shows the part that I used to create the cutouts in each arm. The green box shows a selection box that I tried to select only a few edges. Strangely enough this failed, whereas filleting the whole shape and then cutting the holes that should not be rounded succeeded. Note that I still had to restrict the rounding within a box (using the e.InBox method to avoid rounding the bottom of the shape.

// Three arm as created for Model Mania 2020
// https://blogs.solidworks.com/tech/wp-content/uploads/sites/4/Model-Mania-2020-Phase1-drawing.png
// https://blogs.solidworks.com/tech/wp-content/uploads/sites/4/Model-Mania-2020-Phase2-drawing.png
// free interpretation as not all fillets were possible in Replicad
// and cutout up to central cylinder posed a problem

function main({Sketcher, 
sketchCircle,Lever,
makeCylinder,
makeBaseBox},{})
{

let r1  = 11;
let r2  = 6;
let d   = 35;
let t   = 3;
let h   = 22;
let fl  = 30;
let bb = 16/2; 
let sb = 4.5/2;
let cb = 8/2; 

// function to create a lever consisting of two circles connected with tangent lines 
// 
// radius1 = radius of circle that is located around the origin
// radius2 = radius of circle that is located at distance D along x-axis
// distance = distance between the two circles
// leverheight = distance over which lever is extruded in z-direction
// 
// note that this function creates a closed shape. If you want holes you have to create two cylinders at 
// the correct position, extrude these a bit more than the leverheight and subtract these from the shape.  

function Lever(radius1, radius2, distance, leverHeight)
{
    let sinus_angle = (radius1 - radius2) / distance
    let angle = Math.asin(sinus_angle);

    // points of outer contour of the lever
    let p1 = [radius1 * Math.sin(angle), radius1 * Math.cos(angle)];
    let p2 = [distance + radius2 * Math.sin(angle), radius2 * Math.cos(angle)];
    let p3 = [distance + radius2, 0];
    let p4 = [distance + radius2 * Math.sin(angle), - radius2 * Math.cos(angle)];
    let p5 = [radius1 * Math.sin(angle), - radius1 * Math.cos(angle)];
    let p6 = [- radius1, 0 ];

    let sketchLever = new Sketcher("XY").movePointerTo(p1)
                    .lineTo(p2)
                    .threePointsArcTo(p4,p3)
                    .lineTo(p5)
                    .threePointsArcTo(p1,p6)
                    .close();
              
    let leverBody = sketchLever.extrude(leverHeight);
       
    return leverBody
}


// function to create lever with holes with standard wallthickness around the holes
// radii refer to outer radii, the holes will be radius - wallThickness
// uses the function lever to create the basic shape 

function leverHoles(radius1,radius2,distance,leverHeight,wallThickness)
{ 
    let leverBody = Lever(radius1,radius2,distance,leverHeight);

    let orig_hole  = sketchCircle(radius1-wallThickness).extrude(leverHeight + 10);
    let dist_hole =  sketchCircle(radius2-wallThickness).extrude(leverHeight + 10).translate([distance,0,0]);
    let lever   = leverBody.cut(orig_hole)
    lever       = lever.cut(dist_hole);
    return lever
}

// function to cut part out of lever to make it lighter
// generally the size of the radii is equal to the size of the holes in the lever


function cutLever(r1,r2,d,h,ts,th)
{
    let cLever = Lever(r1-ts,r2,d,h).translate([0,0,th]);
    cLever=cLever.cut(makeCylinder(r1+ts,h+2*th,[0,0,0],[0,0,1]));
    cLever=cLever.cut(makeCylinder(r2+ts,h+2*th,[d,0,0],[0,0,1]));
    return cLever
}

// create three arms, fuse them together and round the edges in z-direction

let arm1 = Lever(r1,r2,d,h);
let arm2 = Lever(r1,r2,d,h).rotate(120,[0,0,0],[0,0,1])
let arm3 = Lever(r1,r2,d,h).rotate(240,[0,0,0],[0,0,1])
let threeArm = arm1.fuse(arm2);
threeArm = threeArm.fuse(arm3).fillet(fl,(e)=>e.inDirection("Z"));

// cut the three arms so that they slope with 22 degrees towards the end

let side = new Sketcher("XZ").movePointerTo([41,6])
.lineTo([50,6]).lineTo([50,30]).lineTo([0,30])
.lineTo([0,22]).lineTo([11,22]).lineTo([11,6+(30*Math.sin(22*Math.PI/180))])
.close()

let sideCutter = side.revolve()
// NOTE: sideCutter is rotated to avoid edge over first arm!!!
sideCutter = sideCutter.rotate(60,[0,0,0],[0,0,1]);
threeArm = threeArm.cut(sideCutter,false,false)

// fillet the top edges, leaving out the central axle
threeArm = threeArm.fillet(1,(e)=>e.inBox([50,50,2],[-50,-50,20]));

// Phase 2: make arms lighter, note that fillet is applied in this stage already
let cutLever1 = cutLever(bb+1,cb,d,h,3,4).fillet(1);
let cutLever2 = cutLever(bb+1,cb,d,h,3,4).rotate(120,[0,0,0],[0,0,1]).fillet(1);
let cutLever3 = cutLever(bb+1,cb,d,h,3,4).rotate(240,[0,0,0],[0,0,1]).fillet(1);
threeArm = threeArm.cut(cutLever1);
threeArm = threeArm.cut(cutLever2);
threeArm = threeArm.cut(cutLever3);

let selBox = makeBaseBox(5,20,12).translate([22.5,0,9])
// experiments to round edges
//threeArm = threeArm.fillet(0.4,(e)=>e.inBox([20,10,3],[25,0,15]));
//threeArm = threeArm.fillet(0.7,(e)=>e.inDirection("Z"));
//threeArm = threeArm.fillet(0.7,(e)=>e.inPlane("XY"));
threeArm = threeArm.fillet(1,(e)=>e.inBox([50,50,2],[-50,-50,21]))

let smallBore1 = makeCylinder(sb,h,[0,0,0],[0,0,1]).translate([35,0,-5]).rotate(120,[0,0,0],[0,0,1])
let smallBore2 = makeCylinder(sb,h,[0,0,0],[0,0,1]).translate([35,0,-5]).rotate(240,[0,0,0],[0,0,1])
let smallBore3 = makeCylinder(sb,h,[0,0,0],[0,0,1]).translate([35,0,-5]).rotate(360,[0,0,0],[0,0,1])
threeArm = threeArm.cut(smallBore1)
threeArm = threeArm.cut(smallBore2)
threeArm = threeArm.cut(smallBore3)

let counterBore1 = makeCylinder(cb,h,[0,0,0],[0,0,1]).translate([35,0,4])
let counterBore2 = makeCylinder(cb,h,[0,0,0],[0,0,1]).translate([35,0,4]).rotate(120,[0,0,0],[0,0,1])
let counterBore3 = makeCylinder(cb,h,[0,0,0],[0,0,1]).translate([35,0,4]).rotate(240,[0,0,0],[0,0,1])
threeArm = threeArm.cut(counterBore1)
threeArm = threeArm.cut(counterBore2)
threeArm = threeArm.cut(counterBore3)

// create holes for axles
let bigBore = sketchCircle(8).extrude(40).translate([0,0,-10]);
threeArm = threeArm.cut(bigBore);

let shapeArray =[{shape: threeArm, color: "steelblue"}
//,{shape: sideCutter, color:"grey", opacity:0.5}
,{shape: cutLever1, color:"red", opacity:0.5}
,{shape: selBox, color:"green", opacity:0.5}
]

return shapeArray;

}