openjscad file for making gauge tools to measure curve radius in mm

metric radius gauges.jscad

/***************************
 * Author: Hovis
 * File: metric radius gauges.jscad
 * Description: This file can be used with openjscad.org to generate 3d models for some tools I designed.  The tools are gauges to measure the radii of inside and outside corners by guess-and-check.  These 3d models are intended to be easy to print on any 3d printer.
 * License: GPL v2
 ***************************/

function main() {
    // These are the mm radii
    var sizes = [2, 3, 4, 5, 6, 7];
    var shapes = [];
    var index = 0;
    sizes.forEach(function(radius) {
        shapes.push(
            radius_gauge(radius).translate([index*radius*5+5, index*-10, 0])
        );
        index++;
    });
   return shapes;
}

function radius_gauge(radius) {
    // This circle will cut out the 45deg corner
    var negative_circle_45 = {
        x: 2*radius,
        y: 2*radius + sqrt(8*pow(radius, 2))
    };
    
    // This circle will cut out the 90deg corner
    var negative_circle_90 = {
        x: -2*radius,
        y: 3.5*radius
    };
    
    // tangent points 1/2 and 3/4 (and the orgigin) describe a polygon that
    // fills the corners before the negative circles are cut away
    var tangent1_x = negative_circle_45.x + radius*cos(180);
    var tangent1_y = negative_circle_45.y + radius*sin(180);
    var tangent2_x = negative_circle_45.x + radius*cos(-45);
    var tangent2_y = negative_circle_45.y + radius*sin(-45);
    var tangent3_x = negative_circle_90.x + radius*cos(270);
    var tangent3_y = negative_circle_90.y + radius*sin(270);
    var tangent4_x = negative_circle_90.x + radius*cos(0);
    var tangent4_y = negative_circle_90.y + radius*sin(0);
    
    var shape = union(
        // Make the rounded-corner box for the 90deg corners
        hull(
            circle({r:radius, center:true}).translate([0, 0]),
            circle({r:radius, center:true}).translate([-3*radius,0]),
            circle({r:radius, center:true}).translate([-3*radius,1.5*radius]),
            circle({r:radius, center:true}).translate([0,1.5*radius])
        ),
        // Add the "straight" leg for the 45deg corner
        hull(
            circle({r:radius, center:true}).translate([0, 0]),
            circle({r:radius, center:true}).translate([0,6*radius])
        ),
        // Add the angled leg for the 45deg corner
        hull(
            circle({r:radius, center:true}).translate([0, 0]),
            circle({r:radius, center:true}).translate([4.5*radius, 4.5*radius])
        ),
        // Add the inside corner polygons
        polygon({points: [ [tangent1_x, tangent1_y], [0,0], [tangent2_x, tangent2_y]]}),
        polygon({points: [ [tangent3_x, tangent3_y], [tangent4_x, tangent4_y], [0,0]]})
    ).extrude().subtract(
        // and cut away the negative circles
        circle({r:radius, center:true}).translate([negative_circle_45.x, negative_circle_45.y]).extrude()
    ).subtract(
        circle({r:radius, center:true}).translate([negative_circle_90.x, negative_circle_90.y]).extrude()
    );
    
    // cut out the hole for hanging tool on a wire
    return shape.subtract(cylinder());
}