[OpenSCAD] Gear looks weird

Chow Loong Jin hyperair at debian.org
Mon May 11 12:00:51 EDT 2015


On Mon, May 11, 2015 at 02:17:50PM +0200, Rainer Glaschick wrote:
> On 11.05.2015 13:38, MichaelAtOz wrote:
> > Perhaps you want involute_gear_tooth()?
> Well, the function/module gear() uses involute_gear_tooth() to create the
> tooth, and I think this is a more or less internal subroutine.
> 
> The module test_gears() just uses gear(), but the gears produced look also not encouraging.
> 
> So my question is if someone has already successfully created nice working
> gears with the library, and how this is done.

Here's my replacement shredder gear, scad included:
http://www.thingiverse.com/thing:343602/

It uses the gear from MCAD/gears/involute_gears.scad from the dev branch, but
<MCAD/involute_gears.scad> from the latest MCAD release should work just as
well.

The most confusing thing about the involute_gears.scad module is that gear()'s
circular pitch is defined in terms of actual circular pitch / PI * 180, so you
need to flip that around. For convenience's sake, and to preserve the meaning of
circular_pitch so that older designs may continue working, I have created a
function called convertcp() that handles this for you.

Here's a sample spur gear:

use <MCAD/gears/involute_gears.scad>

gear (
    number_of_teeth = 20,
    circular_pitch = convertcp (5),
    gear_thickness = 5,
    rim_width = 2,
    hub_diameter = 10,
    bore_dimaeter = 8,
    circles = 7
);


-- 
Kind regards,
Loong Jin
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