Exercise part for tangents

[raydeleu]

I prepared another part as an exercise to model tangent lines in sketches:

// design parameters
let r1 = 25.0   // inner radius
let t  = 5.0    // wall thickness
let d  = 70     // lenght of arm
let h  = 20     // height of arm
let db = 10     // width of arm bracket
let w1 = 35     // width of main cylinder
let w2 = 10     // width of arm
let w3 = 20     // width of arm bracket

// derived parameters
let r0 	= r1 + t;
let dh 	= r0 - h;
let d1	= Math.sqrt(Math.pow(dh,2) + Math.pow(d,2));
let a 	= Math.asin(r0/d1);

// definition of points
let p0 = [0 , -r0 ]
let p1 = [d , -r0 ]
let p2 = [d, - r0 + h ]
let p3 = [r0 * Math.sin(a), r0 * Math.cos(a) ]
let p4 = [-r0, 0 ]
let p5 = [d - db, - r0 , 0]

let contour = new Sketch(p0)
.LineTo(p1)
.LineTo(p2)
.LineTo(p3)
.ArcTo(p4,p0)
.End(false)
.Face(false)

let arm_w3 = Extrude(contour, [0,0,w3])
let arm_box = Translate(p5,Box(db,2*r1,w3))
let arm_bracket = Intersection([arm_w3,arm_box], false)

let arm = Extrude(contour, [0,0,w2])
let part2 = Union([arm_bracket, arm])

let cylinderOuter = Cylinder(r0,w1)
let cylinderInner = Cylinder(r1,w1+5)

let part3 = Union([cylinderOuter,part2],false,0.01,false)
let part4 = Difference(part3, [cylinderInner]);

// create 3-view
let xAxis = [1,0,0]
let yAxis = [0,1,0]
let zAxis = [0,0,1]

let topview = Translate([0,100,r0],Rotate(xAxis, 90, part4, true))
let frontview = Translate([150,0,r0],Rotate(yAxis, -90, part4, true))
let perspview = Translate([150,100,r0],Rotate([1,2,-2], -45, part4, true))

[raydeleu]

A more complicated example of a part that requires tangent constraints is the exercise part of SolidWorks ModelMania 2010 that is often referenced in CAD tutorials. I created my own version as shown below:

Here is the code used to create this part.

// CascadeStudio Code to create a forked lever 
// inspired by ModelMania shape 2010 and 
// exercise created by JokoEngineering 

let radius_1            = 30;
let radius_2            = 10;
let distance            = 120;
let wall_thickness      = 5;
let lever_height        = 50; 
let fillet_cutout       = 5;
let fillet_outer        = 1;
let fillet_arms         = 5;
let depth               = 55;
let chamfer             = 1;

let t1                  = 8;
let t2                  = 10;
let t3                  = 2;
let sep                 = 30;


function Lever(radius1, radius2, distance, leverheight, wall_thickness)
{
    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 Sketch(p1).
                    LineTo(p2).
                    ArcTo(p3,p4).
                    LineTo(p5).
                    ArcTo(p6,p1).
                    End(false).Face(true);
              
    let leverbody = Extrude(sketchLever,[0,0,leverheight]);
  
    let big_hole = Cylinder((radius1-wall_thickness), 2* (leverheight + 10), true);
    let small_hole =  Translate([distance, 0,0 ], Cylinder((radius2-wall_thickness), 2* (leverheight + 10), true));
    let lever = Difference(leverbody,[big_hole, small_hole]);
    return lever
}

function Cutout(radius1, radius2, distance, leverheight, wall_thickness,depth)
{
// points of outer contour of the lever
    let sinus_angle = (radius1 - radius2) / distance
    let angle = Math.asin(sinus_angle);

    distance = distance + 2*wall_thickness;

    let c1 = [radius1 * Math.sin(angle), radius1 * Math.cos(angle)];
    let c2 = [distance + radius2 * Math.sin(angle), radius2 * Math.cos(angle)];
    let c3 = [distance - radius2 , 0];
    let c4 = [distance + radius2 * Math.sin(angle), - radius2 * Math.cos(angle)];
    let c5 = [radius1 * Math.sin(angle), - radius1 * Math.cos(angle)];
    let c6 = [radius1, 0 ];

let cutout  = new Sketch(c1).
                     LineTo(c2).
                     ArcTo(c3,c4).
                     LineTo(c5).
                     ArcTo(c6,c1).
                     End(false).Face(true);
    
cutoutBody = Extrude(cutout,[0,0,leverheight+4*wall_thickness]);
cutoutBody = Translate([-wall_thickness,0,leverheight-wall_thickness-depth],cutoutBody);
cutoutBody = Offset(cutoutBody,-wall_thickness);
return cutoutBody;    
}

function RoundAll(shape,fillet)
{
    let shrunk_version = Offset(shape,-fillet)
    let grown_version = Offset(shrunk_version, fillet)
    return grown_version
}

function SideView(radius1,radius2,distance,sep,t1,t2,t3)
{
    // sketch upper half
    let p1 = [-radius1-t3,sep/2];
    let p2 = [-radius1-t3,sep/2+t1];
    let p3 = [radius1+t3,sep/2+t1];
    let p4 = [distance-radius2-t3,t2/2];
    let p5 = [distance+radius2+t3,t2/2];
    let p6 = [distance+radius2+t3,t2/2-t1]; 
    let p7 = [distance-radius2-t3,t2/2-t1];
    let p8 = [radius1+t3,sep/2];
    let p9 = [-radius1-t3,sep/2];
    
    let halfUpper = new Sketch(p1)
    .LineTo(p2)
    .LineTo(p3)
    .LineTo(p4)
    .LineTo(p5)
    .LineTo(p6)
    .LineTo(p7)
    .LineTo(p8)
    .LineTo(p9)
    .End(false)
    .Face(true);
    return halfUpper
}


// Rollback stack
let lever           = Lever(radius_1,radius_2,distance,lever_height,wall_thickness);
let cutoutShape     = Cutout(radius_1, radius_2, distance, lever_height, wall_thickness,depth);
cutoutShape1        = RoundAll(cutoutShape,fillet_cutout)
lever               = Difference(lever,[cutoutShape1]);
let sideviewUpper   = SideView(radius_1,radius_2,distance,sep,t1,t2,t3);
sideviewUpper       = Translate([0,0,-radius_1],Extrude(sideviewUpper,[0,0,radius_1*2]));
sideviewLower       = Rotate([1,0,0],180,sideviewUpper,true);
let sideviewComplete = Union([sideviewUpper,sideviewLower],false,0.1,false);
sideviewComplete    = FilletEdges(sideviewComplete,fillet_cutout,[22]);
sideviewComplete    = Rotate([1,0,0],90,sideviewComplete);
sideviewComplete    = Translate([0,0,sep/2+t1],sideviewComplete);
let fork            = Intersection([lever,sideviewComplete]);
fork                = FilletEdges(fork,fillet_arms,[69,71,45,48,36,40,19,15,31,25,55],false);
fork                = FilletEdges(fork,fillet_arms,[83],false);
fork                = FilletEdges(fork,fillet_outer,[19,12,23],false);
fork                = ChamferEdges(fork,chamfer,[35,209,219,224],false);

The dimensions are shown in the following sketch. Note that the numbering used for the points in the side view was changed, as I had difficulty calculating the coordinates of point 12 as shown in the sketch. I therefore changed my approach and modelled one half of the shape, mirrored it and then joined them with a boolean Union. This also had its drawbacks, as the Union function required a lot of tweaking to make it work.

Also it should be noted that it is not possible to tweak all variables without breaking the model. The fillets have a large impact on the number of edges that are created. Therefore the numbering of the edges can change with large changes of the fillet radius.

[raydeleu]

Here is an adapted version of the model of the forked lever. I changed the following features:

• Using the extensions to the Sketch function described in my manual (see https://github.com/raydeleu/CascadeStudioManual) I created a complete sketch of the sideview of the lever. Based on the angle of the fork with reference to the XY plane the function PolarY was used to determine the coordinates of the vertex on the XY plane where the two parts come together. In the previous version two halves were joined using a boolean Union function. However, this left some additional edges and made it extremely difficult to find the edge between the two halves of the extruded shape.
• I applied the fillets already in the sketch of the sideview, reducing the number of edges that have to be identified at a later stage. Instead of 15 edges, only 3 edges need to be identified by hovering the mouse in the 3d-view.
• Reducing the number of edges to be identified is particularly important if you want to change the dimensions of the shape. In many cases the edge numbering is completely different when the dimensions of the model are changed. In that case the fillet operation needs to be corrected manually.

// CascadeStudio Code to create a forked lever 
// inspired by ModelMania shape 2010 and 
// exercise created by JokoEngineering 

let t1                  = 8;
let t2                  = 10;
let t3                  = 5;
let sep                 = 40 ;

let radius_1            = 30;
let radius_2            = 12;
let distance            = 120;
let wall_thickness      = 5;
let lever_height        = sep + (4*t1); 
let fillet_cutout       = 5;
let fillet_outer        = 1;
let fillet_arms         = 30;
let depth               = lever_height + fillet_cutout;
let chamfer             = 1;
let angle               = Math.atan((sep/2+t1-t2/2)/(distance - radius_1 - radius_2 - 2*t3))*180/Math.PI; 

function Polar(currentPoint,distance,angleDegToX)
{
    let newPoint = [];
    angleRad = angleDegToX * Math.PI/180;
    newPoint[0]  = currentPoint[0] + distance * Math.cos(angleRad);
    newPoint[1]  = currentPoint[1] + distance * Math.sin(angleRad);
    return newPoint
}

function PolarX(currentPoint,xdistance,angleDegToX)
{
    let newPoint = [];
    let angleRad = angleDegToX * Math.PI/180;
    newPoint[0]  = currentPoint[0] + xdistance;
    newPoint[1]  = currentPoint[1] + xdistance * Math.tan(angleRad);
    return newPoint
}

function PolarY(currentPoint,ydistance,angleDegToX)
{
    let newPoint = [];
    let angleRad = angleDegToX * Math.PI/180;
    newPoint[0]  = currentPoint[0] + ydistance/Math.tan(angleRad);
    newPoint[1]  = currentPoint[1] + ydistance;
    return newPoint
}

function Lever(radius1, radius2, distance, leverheight, wall_thickness)
{
    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 Sketch(p1).
                    LineTo(p2).
                    ArcTo(p3,p4).
                    LineTo(p5).
                    ArcTo(p6,p1).
                    End(false).Face(true);
              
    let leverbody = Extrude(sketchLever,[0,0,leverheight]);
  
    let big_hole = Cylinder((radius1-wall_thickness), 2* (leverheight + 10), true);
    let small_hole =  Translate([distance, 0,0 ], Cylinder((radius2-wall_thickness), 2* (leverheight + 10), true));
    let lever = Difference(leverbody,[big_hole, small_hole]);
    return lever
}

function Cutout(radius1, radius2, distance, leverheight, wall_thickness,depth)
{
// points of outer contour of the lever
    let sinus_angle = (radius1 - radius2) / distance
    let angle = Math.asin(sinus_angle);

    distance = distance + 2*wall_thickness;

    let c1 = [radius1 * Math.sin(angle), radius1 * Math.cos(angle)];
    let c2 = [distance + radius2 * Math.sin(angle), radius2 * Math.cos(angle)];
    let c3 = [distance - radius2 , 0];
    let c4 = [distance + radius2 * Math.sin(angle), - radius2 * Math.cos(angle)];
    let c5 = [radius1 * Math.sin(angle), - radius1 * Math.cos(angle)];
    let c6 = [radius1, 0 ];

let cutout  = new Sketch(c1).
                     LineTo(c2).
                     ArcTo(c3,c4).
                     LineTo(c5).
                     ArcTo(c6,c1).
                     End(false).Face(true);
    
let cutoutBody = Extrude(cutout,[0,0,leverheight+4*wall_thickness]);
cutoutBody = Translate([-wall_thickness,0,leverheight-wall_thickness-depth],cutoutBody);
cutoutBody = Offset(cutoutBody,-wall_thickness);
return cutoutBody;    
}

function RoundAll(shape,fillet)
{
    let shrunk_version = Offset(shape,-fillet)
    let grown_version = Offset(shrunk_version, fillet)
    return grown_version
}

function SideView(radius1,radius2,distance,sep,t1,t2,t3)
{
    // sketch upper half
    let p1 =  [-radius1-t3,sep/2];
    let p2 =  [-radius1-t3,sep/2+t1];
    let p3 =  [radius1+t3,sep/2+t1];
    let p4 =  [distance-radius2-t3,t2/2];
    let p5 =  [distance+radius2+t3,t2/2];
    let p6 =  [distance+radius2+t3,-t2/2]; 
    let p7 =  [distance-radius2-t3,-t2/2];
    let p8 =  [radius1+t3,-sep/2-t1];
    let p9 =  [-radius1-t3,-sep/2-t1];
    let p10 = [-radius1-t3,-sep/2];
    let p11 = [radius1+t3,-sep/2];
    let p12 = PolarY(p11,sep/2,angle);
    let p13 = [radius1+t3,sep/2];
    let p14 = [-radius1-t3,sep/2];
    
    
    let halfUpper = new Sketch(p1)
    .LineTo(p2)
    .LineTo(p3).Fillet(fillet_arms)
    .LineTo(p4).Fillet(fillet_arms)
    .LineTo(p5)
    .LineTo(p6)
    .LineTo(p7).Fillet(fillet_arms)
    .LineTo(p8).Fillet(fillet_arms)
    .LineTo(p9)
    .LineTo(p10)
    .LineTo(p11).Fillet(fillet_arms)
    .LineTo(p12).Fillet(fillet_cutout)
    .LineTo(p13).Fillet(fillet_arms)
    .LineTo(p14)
    .End(false)
    .Face(true);
    return halfUpper
}


// Rollback stack
let lever           = Lever(radius_1,radius_2,distance,lever_height,wall_thickness);
let cutoutShape     = Cutout(radius_1, radius_2, distance, lever_height, wall_thickness,depth);
let cutoutShape1    = RoundAll(cutoutShape,fillet_cutout)
lever               = Difference(lever,[cutoutShape1]);
let sideview        = SideView(radius_1,radius_2,distance,sep,t1,t2,t3);
sideview            = Translate([0,0,-radius_1],Extrude(sideview,[0,0,radius_1*2]));
sideview            = Rotate([1,0,0],90,sideview);
sideview            = Translate([0,0,sep/2+t1],sideview);
let fork            = Intersection([lever,sideview]);
fork                = FilletEdges(fork,fillet_outer,[105,100,97],false);
fork                = ChamferEdges(fork,chamfer,[132,150,143,100,123,93],false);