// Tour Easy front fender clip
// Ed Nisley KE4ZNU July 2017

Layout = "Build";		// Build Profile Ferrule Clip

//- Extrusion parameters must match reality!

ThreadThick = 0.25;
ThreadWidth = 0.40;

HoleWindage = 0.2;

Protrusion = 0.1;			// make holes end cleanly

inch = 25.4;

function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

//----------------------
// Dimensions

// special case: fender is exactly half a circle!

FenderC = 51.0;           // fender outside width = chord
FenderM = 21.0;           // height of chord

FenderR = (pow(FenderM,2) + pow(FenderC,2)/4) / (2 * FenderM);    // radius
echo(str("Fender radius: ", FenderR));
FenderD = 2*FenderR;

FenderA = 2 * asin(FenderC / (2*FenderR));
echo(str(" ... Arc: ",FenderA," deg"));

FenderThick = 2.5;        // fender thickness, assume dia of edge

ClipHeight = 15.0;        // top to bottom, ignoring rakish tilt
ClipThick = IntegerMultiple(2.5,ThreadWidth);          // thickness of clip around fender
ClipD = FenderD;          // ID of clip against fender
ClipSides = 4 * 8;        // polygon sides around clip circle

BendReliefD = 2.5;        // bend arch diameter
BendReliefA = 2/3 * FenderA/2;    // ... angle from dead ahead
BendReliefCut = 1.5;      // factor to thin outside of bend

ID = 0;
OD = 1;
LENGTH = 2;

StayDia = 3.3;              // fender stay rod diameter
StayOffset = 15.0;          // stay-to-fender distance
StayPitch = -5;             // angle from stay to fender arch

DropoutSpace = 120;         // stay spacing at wheel hub
StayLength = 235;           // stay length: hub to fender
StaySplay = asin((DropoutSpace - FenderC)/(2*StayLength));  // outward angle to  hub

echo(str(" ... Pitch: ",StayPitch," deg"));
echo(str(" ... Splay: ",StaySplay," deg"));

FerruleSides = 2*4;
Ferrule = [StayDia,3*FenderThick/cos(180/FerruleSides),10*StayDia + StayOffset];  // ID = stay rod OD
FerruleHoleD = 0.1;         // small hole to create solid plastic at ferrule joint

//----------------------
// Useful routines

module PolyCyl(Dia,Height,ForceSides=0) {			// based on nophead's polyholes

  Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);

  FixDia = Dia / cos(180/Sides);

  cylinder(r=(FixDia + HoleWindage)/2,
           h=Height,
	   $fn=Sides);
}

//----------------------
// Clip profile around fender
// Centered on fender arc

module Profile(HeightScale = 1) {

    linear_extrude(height=HeightScale*ClipHeight,convexity=5) {
      difference() {
        offset(r=ClipThick)                       // outside of clip
          union() {
            circle(d=ClipD,$fn=ClipSides);
            for (i=[-1,1])
              rotate(i*BendReliefA) {
                translate([ClipD/2 + BendReliefD/2,0,0])
                  circle(d=BendReliefD,$fn=6);
              }
          }
        union() {                                 // inside of clip
          circle(d=ClipD,$fn=ClipSides);
          for (i=[-1,1])
            rotate(i*BendReliefA) {
              translate([ClipD/2 + BendReliefCut*BendReliefD/2,0,0])
                circle(d=BendReliefD/cos(180/6),$fn=6);
              translate([ClipD/2,0,0])
                square([BendReliefCut*BendReliefD,BendReliefD],center=true);
            }
        }
        translate([(FenderR - FenderM - FenderD/2),0])  // trim ends
              square([FenderD,2*FenderD],center=true);
      }

     for (a=[-1,1])                                 // hooks around fender
        rotate(a*(FenderA/2))
          translate([FenderR - FenderThick/2,0]) {
            difference() {
              rotate(1*180/12)
                circle(d=FenderThick + 2*ClipThick,$fn=12);
              rotate(1*180/8)
                circle(d=FenderThick,$fn=8);
              rotate(a * -90)
                translate([0,-2*FenderThick,0])
                  square(4*FenderThick,center=false);
            }
      }
    }
}


//----------------------
// Ferrule body

module FerruleBody() {

  translate([0,0,Ferrule[OD]/2 * cos(180/FerruleSides)])
    rotate([0,-90,0]) rotate(180/FerruleSides)
      difference() {
        cylinder(d=Ferrule[OD],h=Ferrule[LENGTH],$fn=FerruleSides,center=false);
        translate([0,0,StayOffset + Protrusion])
          PolyCyl(Ferrule[ID],Ferrule[LENGTH] - StayOffset + Protrusion,FerruleSides);

      }

}

//----------------------
// Generate entire clip at mounting angle

module FenderClip() {

  difference() {
    union() {
      translate([FenderR,0,0])
        difference() {                              // angle and trim clip
          rotate([0,StayPitch,0])
            translate([-(FenderR + ClipThick),0,0])
              Profile(2);                                       // scale upward for trimming
          translate([0,0,-ClipHeight])                          // trim bottom
            cube(2*[FenderD,FenderD,ClipHeight],center=true);
          translate([0,0,ClipHeight*cos(StayPitch)+ClipHeight]) // trim top
            cube(2*[FenderD,FenderD,ClipHeight],center=true);
        }
      for (j = [-1,1])                                          // place ferrules
        translate([Ferrule[OD]*sin(StayPitch) + (Ferrule[OD]/2)*sin(StaySplay),j*(FenderR - FenderThick/2),0])
          rotate(-j*StaySplay)
            FerruleBody();
    }
    for (i=[-1,1])                                  // punch stiffening holes
      translate([FenderThick/2,-i*(FenderR - FenderThick/2),Ferrule[OD]/2])
        rotate([0,-90,i*StaySplay])
          PolyCyl(FerruleHoleD,Ferrule[OD],FerruleSides);

  }
}

//----------------------
// Build it


if (Layout == "Profile") {
	Profile();
}

if (Layout == "Ferrule") {
	FerruleBody();
}

if (Layout == "Clip") {
  FenderClip();
}

if (Layout == "Build") {
  FenderClip();
}