Python - Gearworks

A gear generator in python.

Py-gearworks is built on build123d CAD package. It focuses on accurate geometric representation of gears, gear-pairs. Design calculations related to strength, pitting, efficiency may be implemented in the future - but currently not supported.

Installation

Py_gearworks can be installed via pip:

pip install py-gearworks

pip install git+https://github.com/GarryBGoode/py_gearworks

Alternatively, you can clone or download this repository and install via this command from the repository root directory:

pip install .

Dependencies

py_gearworks CAD model creation uses build123d package: build123d github

compatibility notice

py_gearworks was designed for algebra-style usage of build123d. If users need it in builder context, please use the add() or insert() function as so:

with BuildPart() as build_context:
    add(gear.build_part())
    ...

Improved support of builder contexts is planned for future releases.

It is highly recommended, though not strictly necessary to use a python-CAD gui solution. See OCP VSCode and CadQuery Editor.

Documentation

Docs hosted on readthedocs

Features

It is a development goal that all (sensible) combination of supported features should be combined. Profile shifted cycloids don't exist, but inside-ring-bevel cycloids can be made. Undercut and profile shift is available for bevels - but positioning of profile shifted bevels is lacking. Please use complementary profile shifts for bevels.

* Positioning and backlash design is a bit of work-in-progress. Spur gears and parallel-axis helical gears can be placed with accurate backlash (inc. 0 backlash). This matters for profile shifted gears. Cross-axis helicals and bevel gears can only be positioned via nominal formula (can't adjust backlash via axial distance).

Work in progress / partially supported:

• Racks
• Backlash control
• Contact ratio calculation
• Planetary drive design

Not yet supported:

• Hypoid gears
• Worm gears
• Face / crown gears

Planned upcoming other features

• Backlash, contact ratio and profile shift optimization

Example

The example is built on VSCode with OCP VScode plugin. See examples/examples.py for more.

from py_gearworks import *
from ocp_vscode import show
from build123d import *

# create 2 spur gears
gear1 = SpurGear(
    number_of_teeth=12,
    module=2,
    height=4,
    profile_shift=0.3,
)
gear2 = SpurGear(
    number_of_teeth=23,
    module=2,
    height=4,
)

# move and align gear 1 next to gear 2 in the Y direction
# backlash can be optionally specified
# angle_bias conrtols location within backlash range (-1 to 1)
# backlash is a coefficient of module
# there will be 0.2 mm distance between inactive tooth sides in this example
gear1.mesh_to(gear2, target_dir=UP, backlash=0.1, angle_bias=1)

# generate build123d Part objects
gear_part_1 = gear1.build_part()
gear_part_2 = gear2.build_part()

# center-bores are recommended to be added separately via build123d workflow
# center_location_top can be used as a build123d location object
# location * Hole means placement of Hole at that location (build123d syntax)
hole_obj_1 = gear1.center_location_top * Hole(radius=2, depth=4)
gear_part_1 = gear_part_1.cut(hole_obj_1)
hole_obj_2 = gear2.center_location_top * Hole(radius=2, depth=4)
gear_part_2 = gear_part_2.cut(hole_obj_2)

# export to STEP files (build123d export function)
# note: export retains positioning, gear1 will not be at origin
export_step(gear_part_1, "gear1.step")
export_step(gear_part_2, "gear2.step")

# export to DXF files (build123d export function)
gear_wire_1 = gear1.build_boundary_wire()
gear_wire_2 = gear2.build_boundary_wire()

exporter = ExportDXF(unit=Unit.MM, line_weight=0.5)
exporter.add_layer("Layer 1", line_type=LineType.CONTINUOUS)
exporter.add_shape(gear_wire_1, layer="Layer 1")
exporter.add_shape(gear_wire_2, layer="Layer 1")
exporter.write("gears.dxf")

# visualize parts
show(gear_part_1, gear_part_2)

Name conflict and rebrand

This project was originally named gggears - a poor choice, since it was already taken by another, similar project. I've renamed the project, but some references, URLs might still point to gggears.

License

Project is licensed under Apache 2.0, see license file for details.