I think there is a mistake with the Herringbone gear scad file

Development Hardware
1

Please take it easy on me. I’m new here. I’m new to 3D printing. And I’m new to OpenSCAD. I could be wrong about what I think I’ve found.

Steps to reproduce:

  1. Download:
    http://download.lulzbot.com/AO-101/hardware/printed_parts/source/Herringbone_gears.scad
    http://download.lulzbot.com/AO-101/hardware/printed_parts/source/inc/mendel_misc.inc
    http://download.lulzbot.com/AO-101/hardware/printed_parts/source/inc/parametric_involute_gear_v5.0.scad
  2. Open Herringbone_gears.scad
  3. Render, and observe:

  1. Copy the first call to the gear() function, paste it above the first call to the difference() function, and multiply the rim_thickness by 4 like so:
    https://gist.github.com/RichardBronosky/db15b8e29b3d7eb3857556ecf0a89531/revisions#diff-6b93a0b306ab00452365ac8934ebd408R32
  2. Render and observe:

[] Multiply the twist by 4 like so:
https://gist.github.com/RichardBronosky/db15b8e29b3d7eb3857556ecf0a89531/revisions#diff-6b93a0b306ab00452365ac8934ebd408R38
[] Render and observe:

[/list]

Conclusion:
This indicates that having a twist:rim_thickness ratio of 200:5.5 in the large gear and 200:6.25 in the small gear are causing gears that are slightly mismatched.

Suggestion:
If others agree with my observations I will devise a way to change the math so that the twist is always consistent with a rim_thickness of 5.5 since that is what most people have now.

2

This same conclusion was made by http://www.thingiverse.com/thing:97377/#comment-496408 but no one noticed because he didn’t report it upstream.

How do we submit patches to this?

3

Here is the simplest fix I can think of:
https://gist.github.com/RichardBronosky/db15b8e29b3d7eb3857556ecf0a89531/revisions#diff-6b93a0b306ab00452365ac8934ebd408R27