// chainset.scad

// (c) Simon Brooke 2025; CC-BY-SA
// Derived from Hampus Andersson's Sprocket Generator


include <SprocketGenerator2/files/Sprocket_Generator_v2_example_10.scad>
include <BOSL2/std.scad>

include <pedal.scad>

function sprocket_radius(teeth=52, roller=7.9, pitch=12.7) = let(roller_radius = roller/2,
                radius = pitch/(2*sin(180/teeth)))
                sqrt((radius*radius) - (pitch*(roller_radius+tolerance))+((roller_radius+tolerance)*(roller_radius+tolerance)));
	

module chainring( teeth=52, roller=7.9, pitch=12.7) {
    radius = sprocket_radius(teeth=teeth, roller=roller, pitch=pitch);
    
    echo( "Radius=", radius, "mm");

    difference() {
        color("grey")
        sprocket( teeth=teeth, roller=roller, pitch=pitch);
        
        translate([0, 0, -10])
        cylinder(h=20, r=radius*.75);
    }
}

module spider(radius, arms) {
    for(i=[0:1:5])
        rotate([0,90,i*(360/5)])
            color("grey")
            prismoid(size1=[7, radius/5], size2=[5, radius/7], height=radius*.9);
}


module chainset(teeth=53, arms=5, crank=172, bbshell=68) {
    radius = sprocket_radius(teeth=teeth);
    
    chainring(teeth=teeth);
    spider(radius*.9, 5);
    
    // cranks
    rotate([0, 90, 0])
    translate([6, 0, -10])
    color("grey")
    prismoid(size1=[10, 25], size2=[7, 18], h=crank+20);
 
    rotate([0, 90, 180])
    translate([0 - (12+bbshell), 0, -10])
    color("grey")
    prismoid(size1=[10, 25], size2=[7, 18], h=crank +20);
    
    // pedals
    translate([0-crank, 0, 20 + bbshell])
        pedal();
    translate([crank, 0, 0-4])
        mirror([0, 0, 1])
        pedal();
    
    translate([0, 0, 5])
    color("black")
    cylinder(h=bbshell, r=17);
    
    translate([0, 0, -5])
    color("black")
    cylinder(h= bbshell+20, r=6);
    
}

// chainring();
// spider(90, 1);

chainset(teeth=82, crank=140);