STD Timing Belt Pulley Library for OpenSCAD (S2M, S3M, S5M, S8M, ...)

Generate pulleys and flanges for STD timing belts using this code library. STD stands for "Super Torque Drive". The standard pitches/sizes are S2M, S3M, S5M, and S8M. The less common sizes are S14M (included), S20M (not included), and S4.5M (not included). There are no external dependencies for this timing belt pulley library, other than OpenSCAD itself.

The base of pulley (which contains all the teeth) is generated as a single polyhedron. Each flange is also a polyhedron. Therefore a pulley with two outer flanges consists of only three polyhedra, no matter how many teeth the pulley has. This really improves the efficiency of CSG operations and it reduces the rendering time taken in OpenSCAD. For this reason this code library does not denote a "bore hole" or other shaping construct. It's up to the end-user to finish construction of the pulley for their specific need, by wrapping the modules exposed by this library around lightweight CSG post-processing code.

The API for this library resembles the following:

    use <sXm-pulley.scad>;



    tooth_count = 27;



    s3m_pulley_base(n_teeth= tooth_count,

                    depth= 7.0);



    sXm_pulley_flange(

        thickness= s3m_pulley_flange_default_thickness(),

        angled_r= s3m_pulley_flange_default_angled_r(tooth_count),

        outer_r= s3m_pulley_flange_default_outer_r(tooth_count),

        fraction_angled= 2/3,

        fn= tooth_count * 7);

Many functions are part of the public API, which reveal more information about the dimensions of the pulleys (inner and outer clearance radii of tooth profiles in particular). Much more information is found in the code itself, in the comments therein.

A quick video demo of the sorts of objects that this timing belt pulley library generates:
https://www.youtube.com/watch?v=nrET4eIzs6Y .

In case you're looking for code which generates belts (not pulleys) -- I'm sorry, the code I have for generating belts is not robust enough to be made available for public use, at this point in time. Besides, belts typically involve a very intricate manufacturing process, since they have inner cords which prevent the belt from being elastic. It suffices to say that you cannot 3D print a robust timing belt of this sort.

Please drop me a comment or a like; I want to hear from you.

REVISION HISTORY:

version 1.01 (Dec 27, 2024): Initial version on Thingiverse (#6890043).