Poço com escada helicoidal

// Spiral Staircase in a 1m x 1m x 4m Shaft with Entryway and Slab Opening
// Modeled in millimeters (1m = 1000mm, 4m = 4000mm)

/* [Shaft Dimensions] */
shaft_width = 1000;       // [800:100:1500] Width (X)
shaft_depth = 1000;       // [800:100:1500] Depth (Y)
shaft_height = 4000;      // [2500:100:5000] Height (Z)
wall_thickness = 100;     // [50:10:200] Wall thickness
slab_thickness = 150;     // [100:10:300] Ceiling slab thickness

/* [Door Opening] */
door_width = 800;         // [600:50:950] Door width
door_height = 2100;       // [1800:50:2400] Door height

/* [Spiral Staircase] */
pole_radius = 60;         // [40:5:100] Central column radius
tread_thickness = 40;     // [25:5:60] Tread thickness
stair_radius = 450;       // [350:10:480] Outer radius of spiral stair
num_steps = 22;           // [16:1:28] Total number of steps
total_rotation = 495;     // [360:15:720] Total rotation in degrees (~1.375 turns)

/* [Baluster & Handrail] */
include_railing = true;
railing_height = 850;     // [700:50:1000] Handrail height above tread
post_radius = 12;         // [8:1:20] Handrail baluster post radius
rail_radius = 20;         // [12:2:30] Handrail tube radius

/* [Display Options] */
show_cutaway = true;      // Cutaway of front walls to clearly view interior

$fn = 36;

step_rise = shaft_height / num_steps;
step_angle = total_rotation / num_steps;

module shaft_structure() {
    difference() {
        union() {
            // Main shaft walls
            translate([-shaft_width/2 - wall_thickness, -shaft_depth/2 - wall_thickness, 0])
                cube([shaft_width + 2*wall_thickness, shaft_depth + 2*wall_thickness, shaft_height]);
            // Top slab
            translate([-shaft_width/2 - wall_thickness - 200, -shaft_depth/2 - wall_thickness - 200, shaft_height])
                cube([shaft_width + 2*wall_thickness + 400, shaft_depth + 2*wall_thickness + 400, slab_thickness]);
            // Bottom floor
            translate([-shaft_width/2 - wall_thickness - 200, -shaft_depth/2 - wall_thickness - 200, -slab_thickness])
                cube([shaft_width + 2*wall_thickness + 400, shaft_depth + 2*wall_thickness + 400, slab_thickness]);
        }

        // Inner shaft void
        translate([-shaft_width/2, -shaft_depth/2, -1])
            cube([shaft_width, shaft_depth, shaft_height + 2]);

        // Top slab exit opening (quarter circle / corner cutout to step onto the roof)
        translate([-10, -10, shaft_height - 1])
            cube([shaft_width/2 + 20, shaft_depth/2 + 20, slab_thickness + 2]);

        // Doorway opening on South wall (-Y)
        translate([-door_width/2, -shaft_depth/2 - wall_thickness - 10, 0])
            cube([door_width, wall_thickness + 20, door_height]);

        // Cutaway for visibility if enabled (removes East wall + half South wall)
        if (show_cutaway) {
            translate([0, -shaft_depth/2 - wall_thickness - 210, -slab_thickness - 10])
                cube([shaft_width/2 + wall_thickness + 220, shaft_depth + 2*wall_thickness + 420, shaft_height + slab_thickness + 20]);
        }
    }
}

module single_tread() {
    // Pie-wedge shaped tread
    difference() {
        cylinder(r = stair_radius, h = tread_thickness);
        // Central column cutout
        translate([0,0,-1])
            cylinder(r = pole_radius, h = tread_thickness + 2);
        // Trim wedge angle
        rotate([0, 0, step_angle])
            translate([-stair_radius*1.5, 0, -1])
                cube([stair_radius*3, stair_radius*3, tread_thickness + 2]);
        rotate([0, 0, 180])
            translate([-stair_radius*1.5, 0, -1])
                cube([stair_radius*3, stair_radius*3, tread_thickness + 2]);
    }
    // Collar around central post for structural support
    cylinder(r = pole_radius + 15, h = step_rise);
}

module spiral_staircase() {
    // Central pole
    cylinder(r = pole_radius, h = shaft_height + slab_thickness);

    // Steps
    for (i = [0 : num_steps - 1]) {
        translate([0, 0, i * step_rise])
            rotate([0, 0, i * step_angle]) {
                single_tread();

                // Railing post on outer edge of each tread
                if (include_railing) {
                    rotate([0, 0, step_angle * 0.7])
                        translate([stair_radius - 30, 0, tread_thickness]) {
                            cylinder(r = post_radius, h = railing_height);
                            // Sphere cap / handrail node
                            translate([0, 0, railing_height])
                                sphere(r = rail_radius);
                        }
                }
            }
    }

    // Continuous handrail segments connecting baluster nodes
    if (include_railing) {
        for (i = [0 : num_steps - 2]) {
            hull() {
                rotate([0, 0, i * step_angle + step_angle * 0.7])
                    translate([stair_radius - 30, 0, i * step_rise + tread_thickness + railing_height])
                        sphere(r = rail_radius);

                rotate([0, 0, (i + 1) * step_angle + step_angle * 0.7])
                    translate([stair_radius - 30, 0, (i + 1) * step_rise + tread_thickness + railing_height])
                        sphere(r = rail_radius);
            }
        }
    }
}

// @name Shaft Structure with Door and Slab
shaft_structure();

// @name Spiral Staircase
spiral_staircase();