3d-printing/simple-hook/hook.scad

// ============================================
// Parametrizable Wall Hook
// ============================================
// A simple wall hook with a rectangular base plate
// and a cylindrical peg extending outward.
// Designed for 3D printing.

// ============================================
// CUSTOMIZABLE PARAMETERS
// ============================================

// Length of the hook cylinder (how far it extends from the wall)
hook_cylinder_length = 20; // [10:1:100]

// Upward angle of the hook cylinder in degrees
hook_angle = 0; // [0:1:45]

// Overall scale multiplier (1.0 = default size)
overall_scale = 1.0; // [0.25:0.05:3.0]

// Enable a retaining dent near the tip of the hook (prevents items from sliding off at 0° angle)
hook_dent_enabled = true; // [true, false]

// Width of the retaining dent in mm
hook_dent_width = 10; // [1:0.5:10]

// ============================================
// BASE PARAMETERS
// ============================================

// Base plate dimensions
base_width = 20;      // Width (vertical dimension when mounted)
base_height = 40;     // Height (vertical dimension when mounted)
base_depth = 3;       // Thickness/depth of base plate

// Hook cylinder properties
hook_diameter = 5;    // Diameter of the hook cylinder
fillet_radius = 2;    // Radius for smooth junction between hook and base

// Rendering quality
cylinder_resolution = 50; // Number of facets for cylinders

// ============================================
// PARAMETER VALIDATION
// ============================================

assert(hook_cylinder_length > 0, "Hook cylinder length must be positive");
assert(hook_angle >= 0 && hook_angle <= 45, "Hook angle should be between 0 and 45 degrees");
assert(overall_scale > 0, "Overall scale must be positive");
assert(base_depth >= 3, "Base depth should be at least 3mm for strength");
assert(hook_diameter >= 4, "Hook diameter should be at least 4mm for printability");
assert(hook_dent_width > 0, "Hook dent width must be positive");

// ============================================
// MAIN ASSEMBLY
// ============================================

scale([overall_scale, overall_scale, overall_scale]) {
    difference() {
        union() {
            base_plate();
            hook_cylinder();
        }
        // Cut away anything extending behind the base
        translate([-100, -50, -50])
            cube([100, 100, 200]);
    }
}

// ============================================
// COMPONENT MODULES
// ============================================

// Rectangular base plate, flat back (wall side), rounded front edges on all four sides
module base_plate() {
    corner_radius = 2;

    hull() {
        // Back - full flat rectangle (wall side, sharp edges)
        translate([0, -base_width/2, 0])
            cube([1, base_width, base_height]);

        // Front four corner spheres (create rounded edges on all sides)
        translate([base_depth, -base_width/2 + corner_radius, corner_radius])
            sphere(r=corner_radius, $fn=cylinder_resolution);

        translate([base_depth, base_width/2 - corner_radius, corner_radius])
            sphere(r=corner_radius, $fn=cylinder_resolution);

        translate([base_depth, -base_width/2 + corner_radius, base_height - corner_radius])
            sphere(r=corner_radius, $fn=cylinder_resolution);

        translate([base_depth, base_width/2 - corner_radius, base_height - corner_radius])
            sphere(r=corner_radius, $fn=cylinder_resolution);
    }
}

// Hook cylinder extending from base with upward angle
module hook_cylinder() {
    translate([0, 0, base_height/5])
        rotate([0, 90 + hook_angle*-1, 0]) {
            difference() {
                union() {
                    // Main cylinder body
                    cylinder(h=hook_cylinder_length, d=hook_diameter, $fn=cylinder_resolution);

                    // Rounded cap at the end
                    translate([0, 0, hook_cylinder_length])
                        sphere(d=hook_diameter, $fn=cylinder_resolution);
                }

                // Pill-shaped retaining dent on top of the cylinder near the tip
                if (hook_dent_enabled) {
                    dent_position = hook_cylinder_length - hook_diameter/2 - hook_dent_width/2;
                    translate([0, 0, dent_position])
                        retaining_dent(hook_dent_width, hook_diameter);
                }
            }
        }
}

// Pill-shaped dent cut into the top of the hook cylinder
// Creates a \__/ profile when viewed from the side
module retaining_dent(width, diameter) {
    pill_r = diameter/2;
    half_spread = max(0, width/2 - pill_r);

    // -X in local frame = "up" in world frame (after the 90° Y rotation)
    translate([-diameter/2, 0, 0])
        hull() {
            translate([0, 0, -half_spread])
                sphere(r=pill_r, $fn=cylinder_resolution);
            translate([0, 0, half_spread])
                sphere(r=pill_r, $fn=cylinder_resolution);
        }
}

// Fillet at the junction between hook and base for strength
module fillet_junction() {
    translate([base_depth - 1, 0, base_height/3])
        rotate([0, 90 + hook_angle*-1, 0])
            hull() {
                // Cylinder at the start position
                cylinder(h=0.1, d=hook_diameter, $fn=cylinder_resolution);

                // Larger cylinder slightly behind to create smooth blend with base
                translate([0, 0, -fillet_radius])
                    cylinder(h=0.1, d=hook_diameter + fillet_radius*2, $fn=cylinder_resolution);
            }
}