BDC Motor SCAD
An OpenSCAD library that models a brushed DC hobby motor. The defaults are a “130 size” motor, and every dimension is an argument.
Usage
use <bdc_motor.scad>
hobby_dc_motor(); // the 130 size motor
hobby_dc_motor(motor_body_x = 30, motor_axle_length = 48); // a longer can and axle
The axle lies along the X axis and its driven end is the front. The back face of the motor body is at x = 0; the rear protrusion and the back end of the axle are at negative x.
Opening bdc_motor.scad itself shows the motor with every dimension in the
customizer.
hobby_dc_motor(...)
Each argument has the name and default of the variable at the top of
bdc_motor.scad, where they are described. The ones that are not dimensions:
| Argument | Default | Meaning |
|---|---|---|
render_axle_separately |
true |
Draw the axle as its own solid, separated from the body by a 0.05 mm sleeve. Pass false to get one solid, as when subtracting the motor from another part. |
render_wiring_clearance_blocks |
false |
Add two blocks above the back cover that mark out room for the wires. |
body_alpha, trim_alpha |
40, 20 | Opacity of the body and of the trimmed areas in the preview, in percent. |
measurement_tol |
0.2 | How far a measured dimension may be from the one the others imply, in mm. |
The module stops with a message if the dimensions do not fit together: an axle
shorter than the motor, a back slot outside the rear protrusion, or a
motor_back_protrusion_flat_bottom_width that disagrees with the protrusion’s
diameter and offset.
Circles use 128 fragments, or 64 in the preview, unless you set $fn.
Derived dimensions
For placing other parts around the motor. Each takes the dimensions it depends on as arguments and defaults to the 130 size motor.
| Function | 130 size | Meaning |
|---|---|---|
motor_length() |
29 | The motor without the axle: rear protrusion, back cover, body and front protrusion. |
motor_axle_length() |
38 | Total axle length. |
motor_axle_outset_front() |
8 | Axle protruding from the front protrusion. |
motor_axle_outset_back() |
1 | Axle protruding from the rear protrusion. |
motor_back_start_x() |
3 | From the back end of the axle to the back face of the body. |
motor_body_height() |
15 | Body height across the flats. |
motor_body_width() |
20 | Body width, side to side across the round sides. |
motor_can_x() |
[5, 25] | Where the metal can starts and ends along x, between the back cover and the front protrusion. |
motor_back_height() |
15 | Back cover height, the same as the body’s. |
motor_side_notch_length() |
6 | Length of the notches in the sides of the back cover. |
Examples
examples/custom_motor.scad: a longer can and axle.examples/motor_pocket.scad: the motor and its wiring clearance subtracted from a block.examples/motor_mount.scad: a printable mount, a base with a cradle and a strap that screws down over the can, laid out for printing.
Reference motors
The “130 size” 6 V motor, with a 29 mm long body, that the original author used for reference and testing:
Development
With just and OpenSCAD installed, just test renders
the library and every example with OpenSCAD warnings treated as errors.
License
BSD 3-Clause. See LICENSE. The original is marked “BSD Licensed” in its source, without naming a variant.
Acknowledgement
Originally shared on Thingiverse by Craig Ringer ringerc@ringerc.id.au (Copyright 2019), and forked from ringerc/openscad-hobby-dc-motor. The fork connection was severed as this has diverged significantly from the original.