// Sheet-metal 90° L-bracket (folded part + flat pattern)
// Units mm, Z up. Horizontal leg on Z=0 along +X, vertical leg on X=0 face along +Z.

/* [Mode] */
// "folded" = 3D part, "flat" = 2D unfolded outline (export DXF)
mode = "folded"; // [folded, flat]

/* [Sheet] */
// Material thickness
thickness = 1.5; // [0.5:0.1:6]
// Inside bend radius
bend_radius = 1.5; // [0.1:0.1:10]
// K-factor (neutral axis position)
k_factor = 0.44; // [0.2:0.01:0.5]

/* [Legs] */
// Horizontal leg length, to outside of bend (outer mold line)
leg_a = 40; // [10:1:200]
// Vertical leg length, to outside of bend (outer mold line)
leg_b = 40; // [10:1:200]
// Bracket width (Y)
width = 30; // [10:1:200]

/* [Holes] */
// Hole diameter
hole_d = 5.5; // [1:0.1:20]
// Hole center distance from the bend's outside face
hole_from_bend = 15; // [3:0.5:100]
// Hole center inset from each side edge
hole_edge_inset = 8; // [2:0.5:50]

/* [Hidden] */
$fn = 96;
T = thickness;
R = bend_radius;
Ro = R + T;                       // outside bend radius
setback = Ro;                     // 90° bend: tangent to outer virtual sharp
flat_a = leg_a - setback;         // straight portion of leg A
flat_b = leg_b - setback;         // straight portion of leg B
BA = (PI / 2) * (R + k_factor * T); // bend allowance, 90°
flat_len = flat_a + BA + flat_b;
hole_ys = [hole_edge_inset, width - hole_edge_inset];

module holes_2d(x0) {
    for (y = hole_ys) translate([x0, y]) circle(d = hole_d);
}

module flat_2d() {
    difference() {
        square([flat_len, width]);
        // leg A hole: hole_from_bend - setback from bend tangent; leg A free end at x=0
        holes_2d(flat_a - (hole_from_bend - setback));
        // leg B hole
        holes_2d(flat_a + BA + (hole_from_bend - setback));
    }
}

module folded() {
    difference() {
        union() {
            // leg A (horizontal), Z 0..T, X Ro..leg_a
            translate([Ro, 0, 0]) cube([flat_a, width, T]);
            // leg B (vertical), X 0..T, Z Ro..leg_b
            translate([0, 0, Ro]) cube([T, width, flat_b]);
            // bend: annulus sector, centre axis along Y at (Ro, *, Ro)
            translate([Ro, width, Ro]) rotate([90, 0, 0])
                linear_extrude(width)
                    intersection() {
                        difference() { circle(r = Ro); circle(r = R); }
                        translate([-Ro - 1, -Ro - 1]) square(Ro + 1); // third quadrant
                    }
        }
        // holes in leg A
        for (y = hole_ys) translate([hole_from_bend, y, -1]) cylinder(d = hole_d, h = T + 2);
        // holes in leg B
        for (y = hole_ys) translate([-1, y, hole_from_bend]) rotate([0, 90, 0]) cylinder(d = hole_d, h = T + 2);
    }
}

if (mode == "flat") flat_2d();
else folded();