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// sphere diameter
d = 30;
cutoff = 3;
c = 3;
base = 10;
screw_len = 15;
screw_dia = 25.4/4;
screw_head_len = 5;
mount_screw_dia = 4;
mount_screw_head_dia = 10;
// retainer wire hole diameter
retainer_dia = 1;
e = 0.01;
$fn = 500;
use <simplethreads.scad>;
module screw() {
translate([0, 0, 2*screw_head_len - screw_dia/2])
thread_imperial(1/16, screw_dia/25.4, 12, screw_len*16/25.4);
intersection() {
cylinder(r1=2*screw_head_len, r2=0, h=2*screw_head_len);
cube([2*screw_head_len, 2*screw_head_len, 10*screw_head_len], center=true);
}
}
module two_half_screws()
for (i = [0,1])
translate([i*2*screw_head_len, -i*(screw_len + screw_head_len), 0])
intersection() {
rotate([90, i*180, i*180])
screw();
translate([0, 0, 50])
cube(100, center=true);
}
module grip()
for (i = [0:19])
rotate(i*360/20)
translate([d/2-3, 0, -5/2])
cube([3,2,5]);
module ball()
difference() {
// sphere with top and bottom cap removed
sphere(d/2);
for (i = [-1,1])
translate([0, 0, i * (d - cutoff)]) cube(d, center=true);
// screw hole (thin ot the top, thickening in the center, big
// square at the bottom)
translate([0, 0, d/2 - cutoff - screw_len/2 + screw_head_len/2]) {
cylinder(r=screw_dia/2, h=d, center=true);
mirror([0, 0, 1])
intersection() {
cylinder(r1=0, r2=d, h=d);
cube([2*screw_head_len, 2*screw_head_len, 10*screw_head_len], center=true);
}
}
// horizontal grip
grip();
// vertical grip at the upper half sphere (but not at the top)
difference() {
rotate([90, -5, 0]) grip();
cylinder(r1=0, r2=sqrt(pow(d/2, 2) - pow(d/2-cutoff, 2)), h=d/2-cutoff);
translate([0, 0, -d+4]) cylinder(r=d/2, h=d);
}
}
module shell() {
difference() {
// sphere with cylinder to bottom
mirror([0, 0, 1])
assign(r2=d/2+c)
union() {
sphere(r=r2);
cylinder(r=r2, h=r2 + base);
}
// hollow out the sphere
sphere(d/2);
// add intro region
translate([0, 0, d])
cube([d-2*cutoff, d*2, 2*d], center=true);
// path for 1/4" screw; lets you rotate the sphere after
// pushing it in (and allows later removal of it)
hull() {
cylinder(r=screw_dia/2, h=d);
rotate([90, 0, 90])
cylinder(r=screw_dia/2, h=d);
}
// mounting screw hole
assign(rs=mount_screw_dia)
assign(rh=mount_screw_head_dia)
union() {
cylinder(r=rs/2, h=3*(d+base), center=true);
translate([0, 0, -d/2-rh]) cylinder(r1=0, r2=rh/2, h=rh);
translate([0, 0, -d/2 ]) cylinder(r=rh/2, h=d);
}
// holes for retainer wire
for (i = [-1,1])
translate([i*d/4, 0, -d/2 - base/2 - c])
rotate([90, 0, 0])
cylinder(r=retainer_dia, h=2*d, center=true);
}
}
module shell_splitter()
assign(w1 = d + 2*c + e)
assign(w2 = mount_screw_head_dia + 2*c)
assign(h = base + c)
translate([-w1/2, -w2/2, -h - d/2]) {
cube([w1, w2, 2/3*h+e]);
rotate([90, 0, 90])
translate([w2/2, 2/3*h, 0])
cylinder(h=w1, r=w2/2);
}
module shell_upper()
difference() {
shell();
translate([0, 0, -e]) shell_splitter();
}
module shell_lower()
intersection() {
shell();
shell_splitter();
}
translate([0, 0, -3*base]) shell_lower();
shell_upper();
translate([0,0,20]) rotate([90, 0, 90]) ball();
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