ft-parts/ft_28BYJ-48.scad

// A small collection of parts for the 28BYJ-48 stepper motor:
// - A housing for the stepper motor
// - A coupler to combine the axle of the stepper with an ft clip axle
/* [Stepper options] */
// Type
type = 0; // [0 : no output, 1:Stepper housing, 2:Shaft coupler, 3:Gear coupler, 4:Bevel gears coupler]

/* [Hidden] */

// **********************
// ** Static Settings: **
// **********************
include<ft_util.scad> 
use<ft_gears.scad>

shaft_diameter = 5.1;
shaft_thickness = 3.1;    

// --------------------------------------------------------------------
// A coupler to combine the axle of the stepper with an ft clip axle
// --------------------------------------------------------------------
module shaft_coupler() {
    // All dimensions are defined here, no parameters for the shaft
    // coupler module. Depending on the printer's tolerance, the values 
    // might need some correction. 
    length = BASIC_BLOCK_SIZE;
    diameter = 8.0;
    ft_axis_diameter = 4.25;
    ft_axis_thickness = 2.75;

    difference() {
        cylinder(d = diameter, h = length, center = true);
        union() {
            // cut out the motor axle hole
            translate([0,0,length / 4 + MANIFOLD_CORRECTION / 2])            
                clip_axle_hole(length / 2, diameter = shaft_diameter, thickness = shaft_thickness);
            // cut out the clip axle hole
            translate([0,0,-length / 4 - MANIFOLD_CORRECTION / 2])
                clip_axle_hole(length / 2, diameter = ft_axis_diameter, thickness = ft_axis_thickness, hor_cutout = diameter + MANIFOLD_CORRECTION);
            // cut out the horizontal hole of the axle coupler
            //cube([diameter + MANIFOLD_CORRECTION, ft_axis_thickness, ft_axis_diameter], center = true);
        }
    }
}

// --------------------------------------------------------------------
//  A gear for the stepper
// --------------------------------------------------------------------
module gear_wheel() {
    difference() {
        union() {
            translate([0,0,-4])  
                cylinder(h = 4, d = 8, center = true);
            normalgear (modulus=1.5, teeth=15, height=5, hole=0.0, clipaxle=false, optimize=false);
        }
        translate([0,0,-3])
            clip_axle_hole(diameter = shaft_diameter, thickness = shaft_thickness);
    }
}

// --------------------------------------------------------------------
// Build a pair of bevel gears.
// Both gears have the same size. The hole in one gear is for the 
// stepper and the other hole is for a clip axle.
// --------------------------------------------------------------------
module bevelgears(modulus=1.5, teeth=15, hole=4.2) {
    shaft_diameter = 5.1;
    shaft_thickness = 3.1;    
    ft_axis_diameter = 4.25;
    ft_axis_thickness = 2.75;
    shaft_length = 7.5;
    diameter = 8.0;

    // Calculation for the distance of the bevel gears taken from gears.scad, 
    // eleminated the intermediate steps. Simplify more?
    rkf = (modulus*teeth/2)/sin(45)*sin(((PI*((modulus*teeth/2)/sin(45))*45/90 - 2 * (modulus + modulus / 6)) / 2)/(PI*((modulus*teeth/2)/sin(45))) * 180);

    difference() {
        union() {
            translate([0,0,-shaft_length/2+MANIFOLD_CORRECTION])  
                cylinder(h = shaft_length, d = diameter, center = true);
            translate([rkf*3+modulus,0,-shaft_length/2+MANIFOLD_CORRECTION]) 
                cylinder(h = shaft_length, d = diameter, center = true);

            bevel_gear_pair(modul = modulus, 
                            gear_teeth = teeth, pinion_teeth = teeth, 
                            axis_angle=90, tooth_width = 5, 
                            gear_bore = 0, pinion_bore = 0, 
                            pressure_angle=20, helix_angle=0, 
                            together_built=false);
        }
        translate([0,0,-shaft_length/2]) 
            #clip_axle_hole(shaft_length+MANIFOLD_CORRECTION, diameter = shaft_diameter, thickness = shaft_thickness);
        
        translate([rkf*3+modulus,0,-shaft_length/2]) 
            #clip_axle_hole(shaft_length+MANIFOLD_CORRECTION, diameter = ft_axis_diameter, thickness = ft_axis_thickness, hor_cutout = diameter + MANIFOLD_CORRECTION);
                        
    }
}


// --------------------------------------------------------------------
// A housing for the 28BYJ-48. No back becuse the stepper gets quite 
// warm and the heat has to go somewhere ...
// --------------------------------------------------------------------
module stepper_housing(width = 60, length = 45, height = 30) {
    wallthickness = 4;
    frontthickness = 4;
    screwdistance = 35;
    shaftdistance = 8;
    
    difference() {
        // The housing
        cube([width, length, height], center = true);
        // minus the inner cut out
        translate([0, 0, frontthickness])
            cube([width - 2 * wallthickness, length - 2 * wallthickness, height], center = true);
        // and the grooves
        grooves(width, length, height);
  
        // remove the cut outs for the screws and the axle
        translate([-(screwdistance / 2),0, -(height / 2 + 0.1)])
            cylinder(d = 3, h = 10);
        translate([-(screwdistance / 2),0, -(height / 2 + 0.1)])
            cylinder(d = 5.75, h = 2.5);

        translate([(screwdistance / 2),0, -(height / 2 + 0.1)])
            cylinder(d = 3, h = 10);
        translate([(screwdistance / 2),0, -(height / 2 + 0.1)])
            cylinder(d = 5.75, h = 2.5);
            
        translate([0,shaftdistance, -(height / 2 + 0.1)])
            cylinder(d = 9.5, h = 10);
    }
}

// --------------------------------------------------------------------
// The grooves around the housing for the cut out
// --------------------------------------------------------------------
module grooves(width = 60, length = 45, height = 30) {
        for(i = [0, 180]) {
            rotate([0,0,i])
                for (j = [0 : BASIC_BLOCK_SIZE : (width / BASIC_BLOCK_SIZE - 1) * BASIC_BLOCK_SIZE])
                    translate([j - (width / 2) + BASIC_BLOCK_HALF, -(length / 2), 0])
                        flat_groove(len = height);
        } 
        for(i = [90, 270]) {
            rotate([0,0,i])
                for (j = [0 : 15 : (length / BASIC_BLOCK_SIZE - 1) * BASIC_BLOCK_SIZE])
                    translate([j - (length / 2) + BASIC_BLOCK_HALF, -(width / 2), 0])
                        flat_groove(len = height); 
        }

}



// ********************
// ** Build section: **
// ********************
module main() {
    if (type == 1) {
        stepper_housing();
    }
    else if (type == 2) {
        shaft_coupler();
    }
    else if (type == 3) {
        gear_wheel();
    }
    else if (type == 4) {
        bevelgears(teeth=10);
    }
}

main();