Ventilated Paint Brush Travel Tube

/**
 * Brush Tube Case (Тубус для кисточек) v10
 * 
 * Features in v10:
 * - 3MF export pre-configured in print-ready orientation:
 *   both halves standing side-by-side with flat caps/bases on build plate (Z=0)
 * - Squeak-free, silky-smooth 10.5mm thread with 2.8mm pitch (~3.75 continuous turns)
 * - 0.32mm thread slop for zero-binding Silk PLA operation
 * - Solid top cap center with clean radial ventilation slot rings
 * - Uniform 1.2mm minimum wall thickness throughout
 * - 22mm internal radius (44mm ID), 250mm total interior length
 * - 100% support-free 3D printing
 */

include <BOSL2/std.scad>
include <BOSL2/threading.scad>

/* [Main Dimensions] */
// Total assembled interior length (mm)
total_length = 250; // [150:10:400]
// Internal radius of the tube (mm)
inner_radius = 22; // [15:1:50]
// Main tube outer wall thickness (mm)
wall_thickness = 1.2; // [1.0:0.1:3.0]
// Base & top end plate thickness (mm)
end_thickness = 1.6; // [1.2:0.2:3.0]

/* [Thread & Collar Parameters] */
// Thread pitch (mm)
thread_pitch = 2.8; // [2.0:0.2:4.5]
// Thread engagement height (mm)
thread_height = 10.5; // [8.0:0.5:18.0]
// Thread profile depth (mm)
thread_depth = 0.72; // [0.4:0.05:1.0]
// Thread angle (degrees)
thread_angle = 45; // [30:5:60]
// 3D printer clearance/slop (mm)
thread_slop = 0.32; // [0.15:0.02:0.5]
// Minimum wall thickness under thread spigot root (mm)
min_spigot_wall = 1.2; // [1.0:0.1:2.0]
// Minimum wall thickness over female thread socket (mm)
min_female_wall = 1.2; // [1.0:0.1:2.0]
// Height of the reinforced collar zone (mm)
joint_collar_height = 12.0; // [8.0:1.0:20.0]
// Transition bevel length (mm)
joint_collar_trans = 3.0; // [1.5:0.5:5.0]

/* [Ventilation] */
// Enable top end cap ventilation pattern
enable_top_ventilation = true;
// Style of top cap ventilation
top_vent_style = "radial_slots"; // [radial_slots:Radial Slots, circular_holes:Circular Holes, spiral_slots:Spiral Rosette]
// Enable upper sidewall ventilation slots
enable_side_ventilation = true;
// Number of sidewall ventilation slot columns
side_vent_columns = 10; // [6:1:18]
// Height of sidewall ventilation slots (mm)
side_vent_height = 20; // [10:2:35]
// Width of sidewall ventilation slots (mm)
side_vent_width = 2.4; // [1.5:0.1:4.0]

/* [Grip & Texture] */
// Enable tactile fluting / knurling grip ribs
enable_grip_fluting = true;
// Number of grip flutes around perimeter
grip_flutes_count = 28; // [16:2:48]
// Depth of grip flutes (mm)
grip_flute_depth = 0.30; // [0.15:0.05:0.6]

/* [View & Export Mode] */
// Select what to render
part_view = "print_plate"; // [print_plate:Print Plate (Both Halves Cap/Base Down), assembled:Assembled Full View, separated:Exploded / Separated, bottom_only:Bottom Half (Base on Bed), top_only:Top Half (Cap on Bed), cross_section:Cross Section Cutaway]

/* [Hidden] */
$fn = $preview ? 72 : 128;

// Derived geometry values
d_in = inner_radius * 2;
r_out = inner_radius + wall_thickness;
d_out = r_out * 2;

// Spigot and Thread dimensions
spigot_root_r = inner_radius + min_spigot_wall;
thread_major_r = spigot_root_r + thread_depth;
thread_major_d = thread_major_r * 2;

// Reinforced collar outer radius (guarantees min_female_wall thickness over internal thread socket)
r_joint = thread_major_r + thread_slop + min_female_wall;
d_joint = r_joint * 2;

bottom_half_len = total_length / 2;
top_half_len = total_length / 2;

// -------------------------------------------------------------------------
// Grip Fluting Cutter
// -------------------------------------------------------------------------
module grip_fluting_mask(h, r, flute_count, depth) {
    if (enable_grip_fluting) {
        for (i = [0 : flute_count - 1]) {
            rotate([0, 0, i * 360 / flute_count])
            translate([r, 0, 0])
            cylinder(r = depth, h = h, center = true, $fn = 16);
        }
    }
}

// -------------------------------------------------------------------------
// Top Ventilation Patterns (Solid center)
// -------------------------------------------------------------------------
module top_ventilation_mask() {
    if (enable_top_ventilation) {
        if (top_vent_style == "radial_slots") {
            // Inner ring slots (6 slots)
            for (i = [0 : 5]) {
                rotate([0, 0, i * 60])
                translate([8.5, 0, 0])
                rotate([0, 0, 90])
                rect_tube(size=[2.2, 5.0], h=end_thickness * 4, rounding=1.1);
            }
            // Outer ring slots (12 slots)
            for (i = [0 : 11]) {
                rotate([0, 0, i * 30 + 15])
                translate([15.5, 0, 0])
                rotate([0, 0, 90])
                rect_tube(size=[2.2, 6.0], h=end_thickness * 4, rounding=1.1);
            }
        } else if (top_vent_style == "circular_holes") {
            // Ring 1 (6 holes)
            for (i = [0 : 5]) {
                rotate([0, 0, i * 60])
                translate([8.5, 0, 0])
                cylinder(r = 1.8, h = end_thickness * 4, center = true, $fn = 18);
            }
            // Ring 2 (12 holes)
            for (i = [0 : 11]) {
                rotate([0, 0, i * 30 + 15])
                translate([15.5, 0, 0])
                cylinder(r = 2.0, h = end_thickness * 4, center = true, $fn = 18);
            }
        } else if (top_vent_style == "spiral_slots") {
            for (i = [0 : 7]) {
                rotate([0, 0, i * 45])
                for (r_pos = [7.5, 14.5]) {
                    rotate([0, 0, r_pos * 2.2])
                    translate([r_pos, 0, 0])
                    rotate([0, 0, 45])
                    rect_tube(size=[2.0, 5.0], h=end_thickness * 4, rounding=1.0);
                }
            }
        }
    }
}

// Helper 2D/3D rounded rectangle slot for top cap
module rect_tube(size, h, rounding) {
    linear_extrude(height = h, center = true, convexity = 4)
    rect(size = size, rounding = rounding);
}

// -------------------------------------------------------------------------
// Sidewall Ventilation Slots
// -------------------------------------------------------------------------
module sidewall_ventilation_mask(z_center) {
    if (enable_side_ventilation) {
        for (i = [0 : side_vent_columns - 1]) {
            rotate([0, 0, i * 360 / side_vent_columns])
            translate([0, 0, z_center])
            rotate([90, 0, 0])
            linear_extrude(height = r_out * 3, center = true, convexity = 4)
            rect(size = [side_vent_width, side_vent_height], rounding = side_vent_width / 2);
        }
    }
}

// -------------------------------------------------------------------------
// Bottom Half Module (Standard upright orientation, base at Z=0)
// -------------------------------------------------------------------------
module bottom_half() {
    collar_start_z = bottom_half_len - joint_collar_height;
    trans_start_z = collar_start_z - joint_collar_trans;

    difference() {
        union() {
            // Main lower tube body
            cyl(
                d = d_out,
                h = trans_start_z,
                chamfer1 = 1.0,
                chamfer2 = 0,
                anchor = BOTTOM
            );

            // Tapered transition to reinforced collar
            translate([0, 0, trans_start_z])
            cyl(
                d1 = d_out,
                d2 = d_joint,
                h = joint_collar_trans,
                anchor = BOTTOM
            );

            // Reinforced collar section
            translate([0, 0, collar_start_z])
            cyl(
                d = d_joint,
                h = joint_collar_height,
                anchor = BOTTOM
            );

            // Continuous Male threaded spigot (full spiral with top lead-in & bevel)
            translate([0, 0, bottom_half_len])
            trapezoidal_threaded_rod(
                d = thread_major_d,
                l = thread_height,
                pitch = thread_pitch,
                thread_depth = thread_depth,
                thread_angle = thread_angle,
                blunt_start1 = false,
                blunt_start2 = true,
                bevel2 = true,
                anchor = BOTTOM
            );
        }

        // Internal cylindrical cavity (smooth continuous bore R=22mm)
        translate([0, 0, end_thickness])
        cyl(
            d = d_in,
            h = bottom_half_len + thread_height + 5,
            anchor = BOTTOM
        );

        // Chamfer on inner bottom base for easy cleaning
        translate([0, 0, end_thickness - 0.01])
        cyl(
            d1 = d_in - 2,
            d2 = d_in,
            h = 0.8,
            anchor = BOTTOM
        );

        // Grip flutes on the reinforced collar
        translate([0, 0, bottom_half_len - joint_collar_height / 2])
        grip_fluting_mask(
            h = joint_collar_height - 2,
            r = r_joint,
            flute_count = grip_flutes_count,
            depth = grip_flute_depth
        );

        // Grip flutes near the bottom base
        translate([0, 0, 16])
        grip_fluting_mask(
            h = 16,
            r = r_out,
            flute_count = grip_flutes_count,
            depth = grip_flute_depth
        );
    }
}

// -------------------------------------------------------------------------
// Top Half Module (Standard upright orientation, rim at Z=0, cap at Z=top_half_len)
// -------------------------------------------------------------------------
module top_half() {
    collar_end_z = joint_collar_height;
    trans_end_z = collar_end_z + joint_collar_trans;

    difference() {
        union() {
            // Reinforced collar section around female thread
            cyl(
                d = d_joint,
                h = collar_end_z,
                anchor = BOTTOM
            );

            // Tapered transition down to main tube body
            translate([0, 0, collar_end_z])
            cyl(
                d1 = d_joint,
                d2 = d_out,
                h = joint_collar_trans,
                anchor = BOTTOM
            );

            // Main upper tube body
            translate([0, 0, trans_end_z])
            cyl(
                d = d_out,
                h = top_half_len - trans_end_z,
                chamfer2 = 1.0,
                anchor = BOTTOM
            );
        }

        // Internal cylindrical cavity
        translate([0, 0, -1])
        cyl(
            d = d_in,
            h = top_half_len - end_thickness + 1,
            anchor = BOTTOM
        );

        // Female internal thread socket matching male thread
        translate([0, 0, -0.1])
        trapezoidal_threaded_rod(
            d = thread_major_d,
            l = thread_height + 0.4,
            pitch = thread_pitch,
            thread_depth = thread_depth,
            thread_angle = thread_angle,
            internal = true,
            blunt_start1 = true,
            blunt_start2 = false,
            bevel1 = true,
            anchor = BOTTOM,
            $slop = thread_slop
        );

        // Top end cap ventilation holes (No central hole)
        translate([0, 0, top_half_len - end_thickness / 2])
        top_ventilation_mask();

        // Upper sidewall ventilation slots
        sidewall_ventilation_mask(z_center = top_half_len - end_thickness - side_vent_height / 2 - 4);

        // Grip flutes on the reinforced collar of top half
        translate([0, 0, joint_collar_height / 2])
        grip_fluting_mask(
            h = joint_collar_height - 2,
            r = r_joint,
            flute_count = grip_flutes_count,
            depth = grip_flute_depth
        );
    }
}

// -------------------------------------------------------------------------
// Top Half Inverted Module (Cap down on build plate Z=0, threaded socket up)
// -------------------------------------------------------------------------
module top_half_cap_down() {
    translate([0, 0, top_half_len])
    rotate([180, 0, 0])
    top_half();
}

// -------------------------------------------------------------------------
// Render Selector
// -------------------------------------------------------------------------
if (part_view == "print_plate") {
    // Both parts side-by-side with bottoms/caps down on Z=0 build plate (Print-Ready)
    translate([-d_joint * 0.65, 0, 0])
    color("#1E88E5") bottom_half();
    
    translate([d_joint * 0.65, 0, 0])
    color("#FB8C00") top_half_cap_down();
}
else if (part_view == "assembled") {
    // Both halves fully screwed together
    color("#1E88E5") bottom_half();
    color("#FB8C00") translate([0, 0, bottom_half_len]) top_half();
}
else if (part_view == "separated") {
    // Exploded view showing threads and alignment
    color("#1E88E5") bottom_half();
    color("#FB8C00") translate([0, 0, bottom_half_len + thread_height + 30]) top_half();
}
else if (part_view == "bottom_only") {
    // Bottom half on build plate (Z=0 base down)
    color("#1E88E5") bottom_half();
}
else if (part_view == "top_only") {
    // Top half oriented for printing (cap down on build plate Z=0)
    color("#FB8C00") top_half_cap_down();
}
else if (part_view == "cross_section") {
    // Cross-section cutaway showing wall thickness, thread engagement, and internal cavity
    front_half(s=500) {
        color("#1E88E5") bottom_half();
    }
    front_half(s=500) {
        color("#FB8C00") translate([0, 0, bottom_half_len]) top_half();
    }
}