gridfinity-rebuilt-openscad/gridfinity-rebuilt-holes.scad

/**
 * @file gridfinity-rebuilt-holes.scad
 * @brief Functions to create different types of holes in an object.
 */

include <standard.scad>

/**
 * @brief Wave generation function for wrapping a circle.
 * @param t An angle of the circle.  Between 0 and 360 degrees.
 * @param count The number of **full** waves in a 360 degree circle.
 * @param range **Half** the difference between minimum and maximum values.
 * @param vertical_offset A simple offset.
 * @details
 *    If plotted on an x/y graph this produces a standard sin wave.
 *    Range only seems weird because it describes half a wave.
 *    Mapped by doing [sin(t), cost(t)] * wave_function(...).
 *    When wrapping a circle:
 *      Final Outer radius is (wave_vertical_offset + wave_range).
 *      Final Inner radius is (wave_vertical_offset - wave_range).
 */
function wave_function(t, count, range, vertical_offset) =
    (sin(t * count) * range) + vertical_offset;

/**
 * @brief A circle with crush ribs to give a tighter press fit.
 * @details Extrude and use as a negative modifier.
 *          Idea based on Slant3D's video at 5:20 https://youtu.be/Bd7Yyn61XWQ?t=320
 *          Implementaiton is completely different.
 *          Important: Lower ribs numbers just result in a deformed circle.
 * @param outer_radius Final outer radius.
 * @param inner_radius Final inner radius.
 * @param ribs Number of crush ribs the circle has.
**/
module ribbed_circle(outer_radius, inner_radius, ribs) {
    assert(outer_radius > 0, "outer_radius must be positive");
    assert(inner_radius > 0, "inner_radius must be positive");
    assert(ribs > 0, "ribs must be positive");
    assert(outer_radius > inner_radius, "outer_radius must be larger than inner_radius");
    
    wave_range = (outer_radius - inner_radius) / 2;
    wave_vertical_offset = inner_radius + wave_range;
    
    // Circe with a wave wrapped around it
    wrapped_circle = [ for (i = [0:360])
        [sin(i), cos(i)] * wave_function(i, ribs, wave_range, wave_vertical_offset)
    ];
    
    polygon(wrapped_circle);
}


/**
 * @brief A cylinder with crush ribs to give a tighter press fit.
 * @details To be used as the negative for a hole.
 * @see ribbed_circle
 * @param outer_radius Outer Radius of the crush ribs.
 * @param inner_radius Inner Radius of the crush ribs.
 * @param height Cylinder's height.
 * @param ribs Number of crush ribs.
 */
module hole_crush_ribs(outer_radius, inner_radius, height, ribs) {
    assert(height > 0, "height must be positive");
    linear_extrude(height)
    ribbed_circle(
        outer_radius,
        inner_radius,
        ribs
    );
}

/**
 * @brief A single magnet and screw hole.
 * @param screw_radius Radius of the screw hole.
 * @param magnet_radius Radius of the magnet hole.
 * @param screw_depth Depth of the screw hole.
 * @param magnet_depth Depth of the magnet hole.
 * @details This is the negative designed to be cut out of the base.
 */
module magnet_and_screw_hole(screw_radius, magnet_radius, screw_depth, magnet_depth) {
    union() {
        cylinder(h = magnet_depth, r=magnet_radius);
        cylinder(h = screw_depth, r = screw_radius);
    }
}

/**
 * @brief A single magnet and screw hole, designed to be printed without supports.
 * @see https://www.youtube.com/watch?v=W8FbHTcB05w
 * @param screw_radius Radius of the screw hole.
 * @param magnet_radius Radius of the magnet hole.
 * @param screw_depth Depth of the screw hole.
 * @param magnet_depth Depth of the magnet hole.
 * @details This is the negative designed to be cut out of the base.
 */
module magnet_and_screw_hole_printable(screw_radius, magnet_radius, screw_depth, magnet_depth) {
    difference() {
        magnet_and_screw_hole(screw_radius, magnet_radius, screw_depth, magnet_depth + h_slit);

        translate([-1.5*magnet_radius, screw_radius+0.1, magnet_depth])
        cube([magnet_radius*3, magnet_radius*3, 10]);
        
        // Equivalent to copy_mirror([0,1,0])
        mirror([0,1,0])
        translate([-1.5*magnet_radius, screw_radius+0.1, magnet_depth])
        cube([magnet_radius*3, magnet_radius*3, 10]);
    }
}

/**
 * @brief A single magnet/screw hole.  To be cut out of the base.
 * @pram style_hole Determines the type of hole that will be generated.
         Style 4 handled elsewhere!
 * @param o Offset
 * @details
 *      Just calls the appropriate function with an offset from the constants.
 *      - 0: No holes. Does nothing.
 *      - 1: Magnet holes only
 *      - 2: Magnet and screw holes - no printable slit.
 *      - 3: Magnet and screw holes - printable slit.
 *      - 4: Gridfinity Refined hole - no glue needed. Not handled here!
 *      - 5: Magnet hole with crush ribs.
 */
module block_base_hole(style_hole, o=0) {
    assert(style_hole >= 0 && style_hole <= 5, "Unhandled Hole Style");
    assert(style_hole != 4, "Gridfinity Refined holes are handled by refined_hole()");

    screw_radius = SCREW_HOLE_RADIUS - (o/2);
    magnet_radius = MAGNET_HOLE_RADIUS - (o/2);
    magnet_inner_radius = MAGNET_HOLE_CRUSH_RIB_INNER_RADIUS - (o/2);
    screw_depth = h_base-o;
    magnet_depth = MAGNET_HOLE_DEPTH - o;

    if (style_hole == 1) {
        cylinder(h = magnet_depth, r=magnet_radius);
    }
    if (style_hole == 2) {
        magnet_and_screw_hole(screw_radius, magnet_radius, screw_depth, magnet_depth);
    }
    if (style_hole==3) {
        magnet_and_screw_hole_printable(screw_radius, magnet_radius, screw_depth, magnet_depth);
    }
    if (style_hole == 5) {
        hole_crush_ribs(magnet_radius, magnet_inner_radius, magnet_depth, MAGNET_HOLE_CRUSH_RIB_COUNT);
    }
}