I'm trying to make a rounded beam in OpenSCAD, I made it rounded by joining two circles and a cube.
Here is the current OpenSCAD script and output:
//! @author Orso Eric https://github.com/OrsoEric // Parameters for the plate and holes nx_beam_length = 58.4; // Length of the plate ny_beam_width = 8.0; // Width of the plate nz_beam_thickness = 2.0; // Thickness of the plate nx_hole_interaxis = 50.0; // Distance between the centers of the holes nd_hole = 2.2; // Diameter of the holes // Translate the entire structure up by half the thickness of the plate // This is done so that the plate is centered at the origin along the z-axis translate([0,0,nz_beam_thickness/2]) difference() // Subtracts the second shape (the holes) from the first shape (the plate) { union() // Combines multiple shapes into one { // The main part of the plate, a cube with the specified length, width, and thickness // The length is reduced by the width of the plate to make room for the cylinders at the ends cube([nx_beam_length - ny_beam_width, ny_beam_width, nz_beam_thickness], center=true); // A cylinder at one end of the plate to create a rounded corner // The cylinder is translated to the end of the cube // The diameter of the cylinder is equal to the width of the plate translate([-(nx_beam_length - ny_beam_width)/2, 0, 0]) cylinder(h=nz_beam_thickness, d=ny_beam_width, center=true, $fn=50); // A cylinder at the other end of the plate to create a rounded corner // The cylinder is translated to the end of the cube // The diameter of the cylinder is equal to the width of the plate translate([(nx_beam_length - ny_beam_width)/2, 0, 0]) cylinder(h=nz_beam_thickness, d=ny_beam_width, center=true, $fn=50); } // A hole at one side of the plate // The hole is a cylinder with the specified diameter and a height slightly larger than the thickness of the plate // The hole is translated to the correct location on the plate translate([nx_hole_interaxis/2, 0, 0]) cylinder(h=nz_beam_thickness+1, r=nd_hole/2, center=true, $fn=50); // A hole at the other side of the plate // The hole is a cylinder with the specified diameter and a height slightly larger than the thickness of the plate // The hole is translated to the correct location on the plate translate([-nx_hole_interaxis/2, 0, 0]) cylinder(h=nz_beam_thickness+1, r=nd_hole/2, center=true, $fn=50); }
Now I want to make the center thinner in a hourglass like shape like this sketch, with a parametric center width (starting from 6.0mm)
How can I do it?
SOLUTION
The rounded poly library does exactly what I need it to do and it works well.
I added two features to the final beam:
- A strengthening fin to prevent torsion
- Two features inside the suspended_hole library to be able to 3D print a hole, with a bigger nut hole below it, meant to neatly accomodate a nut.
Below, the code to generate the beam, it depends on the rounded poly library, and my suspended_hole library
//! @author Orso Eric https://github.com/OrsoEricinclude <polyround.scad>include <suspended_hole.scad>// Parameters for the plate and holesnx_beam_length = 58.4; // Length of the plateny_beam_width = 8.0; // Width of the plategny_beam_width_narrow = 4.0; //The beam narrows in the centernz_beam_thickness = 2.5; // Thickness of the platenx_hole_interaxis = 50.0; // Distance between the centers of the holes//Nut seatnd_nut_diameter = 5.0;nz_nut_thickness = 1.0;//rodnd_rod = 2.3;//Vertical fin to strengthen the beamflag_enable_fin = true;gnx_fin_length = 40;gny_fin_thickness = 1.5;gnz_fin_height = 3.0; // Height of the finmodule rounded_fin( inx_length, iny_thickness, inz_height, inr_round_factor = 2){ aan_points = ([ [-inx_length/2, 0, 0], [+inx_length/2, 0, 0], [+inx_length/2, inz_height, inr_round_factor *iny_thickness], [-inx_length/2, inz_height, inr_round_factor *iny_thickness], ]); translate([0,iny_thickness/2,0]) rotate([90,0,0]) linear_extrude(iny_thickness) polygon(polyRound(aan_points,100));}module rounded_hourglass(inx_length, iny_width_wide, iny_width_narrow, inz_height, inr_round_factor_corner = 0.3, inr_round_factor_neck = 2 ){ aan_points = ([ [0, iny_width_narrow/2,inr_round_factor_neck *inx_length], [inx_length/2, iny_width_wide/2,inr_round_factor_corner *iny_width_wide], [inx_length/2, -iny_width_wide/2,inr_round_factor_corner *iny_width_wide], [0, -iny_width_narrow/2,inr_round_factor_neck *inx_length], [-inx_length/2, -iny_width_wide/2,inr_round_factor_corner *iny_width_wide], [-inx_length/2, iny_width_wide/2, inr_round_factor_corner *iny_width_wide] ]); linear_extrude(inz_height) polygon(polyRound(aan_points,100));}module mini_pupper_bone_v2(){ difference() { union() { translate([0,0,0]) rounded_hourglass(nx_beam_length, ny_beam_width, gny_beam_width_narrow, nz_beam_thickness ); translate([0,0,nz_beam_thickness]) rounded_fin( gnx_fin_length, gny_fin_thickness, gnz_fin_height ); }; union() { translate([-nx_hole_interaxis/2,0,0]) suspended_hole ( nd_nut_diameter, nz_nut_thickness, nd_rod, nz_beam_thickness -nz_nut_thickness, 0.5 ); translate([+nx_hole_interaxis/2,0,0]) suspended_hole ( nd_nut_diameter, nz_nut_thickness, nd_rod, nz_beam_thickness -nz_nut_thickness, 0.5 ); }; }}mini_pupper_bone_v2();Below the result of test block with the two features enabled and disabled. With both enabled, I can 3D print a small hole stacked on top of a larger hole without it collapsing.
Below the content of "suspended_hole.scad", it solves the issue that I had of the shaft hole collapsing inside the nut hole when 3D printing.
//! @author Orso Eric https://github.com/OrsoEric//Layer height of the 3D printergn_layer_height = 0.2;module base_cylinder(in_diameter, in_height, in_precision = 5){ linear_extrude(in_height) circle(d = in_diameter, $fs = 0.1+in_precision, $fa = 0.1+in_precision*3/5);}module rounded_rectangle( inx_length, iny_length, inz_height, ind_rounding, in_precision = 0.5 ){ linear_extrude( inz_height ) union() { square([inx_length-ind_rounding,iny_length], center=true); square([inx_length,iny_length-ind_rounding], center=true); translate([-(inx_length/2-ind_rounding/2), -(iny_length/2-ind_rounding/2), 0]) circle(d=ind_rounding, $fs = 0.1+in_precision, $fa = 0.1+in_precision*3/5); translate([-(inx_length/2-ind_rounding/2), +(iny_length/2-ind_rounding/2), 0]) circle(d=ind_rounding, $fs = 0.1+in_precision, $fa = 0.1+in_precision*3/5); translate([+(inx_length/2-ind_rounding/2), -(iny_length/2-ind_rounding/2), 0]) circle(d=ind_rounding, $fs = 0.1+in_precision, $fa = 0.1+in_precision*3/5); translate([+(inx_length/2-ind_rounding/2), +(iny_length/2-ind_rounding/2), 0]) circle(d=ind_rounding, $fs = 0.1+in_precision, $fa = 0.1+in_precision*3/5); }}module suspended_hole( in_big_diameter, in_big_height, in_small_diameter, in_small_height, in_precision = 5, in_wide_feature = gn_layer_height, in_narrow_feature = gn_layer_height ){ base_cylinder( in_big_diameter, in_big_height-in_wide_feature, in_precision ); if (in_wide_feature > 0) translate([0,0,in_big_height-gn_layer_height]) rounded_rectangle( in_big_diameter, in_small_diameter, in_wide_feature, in_big_diameter/3, in_precision/2); if (in_narrow_feature > 0) translate([0,0,in_big_height]) rounded_rectangle( in_small_diameter, in_small_diameter, in_narrow_feature, in_small_diameter/3, in_precision/2); translate([0,0,in_big_height+in_narrow_feature]) base_cylinder( in_small_diameter, in_small_height - in_narrow_feature, in_precision );}//Block with four styles of suspended holes with different combination of wide and narrow featuresmodule test_bench(){ nd_hole_big = 8; nh_hole_big = 2; nd_hole_small = 3.2; nh_hole_small = 12; n_block_size = nd_hole_big *3; n_block_height = nh_hole_big +nh_hole_small; n_hole_pitch = nd_hole_big *0.75; difference() { union() { rounded_rectangle( n_block_size, n_block_size, n_block_height, 10); }; translate([-n_hole_pitch, -n_hole_pitch, 0 ]) suspended_hole(nd_hole_big, nh_hole_big, nd_hole_small, nh_hole_small, 0.5, 0, 0); translate([-n_hole_pitch, +n_hole_pitch, 0 ]) suspended_hole(nd_hole_big, nh_hole_big, nd_hole_small, nh_hole_small, 0.5, gn_layer_height, 0); translate([+n_hole_pitch, -n_hole_pitch, 0 ]) suspended_hole(nd_hole_big, nh_hole_big, nd_hole_small, nh_hole_small, 0.5, 0, gn_layer_height); translate([+n_hole_pitch, +n_hole_pitch, 0 ]) suspended_hole(nd_hole_big, nh_hole_big, nd_hole_small, nh_hole_small, 0.5, gn_layer_height, gn_layer_height); }}//suspended_hole( 30, 5, 10, 20, 1, 0, 0 ); //test_bench();