Gears with custom-cut tooth styles

prusaprinters

<p>This is a remix of <a href="https://www.thingiverse.com/parkinbot/designs">Parkinbo</a><a href="/parkinbot/designs">t</a>'s <a href="https://www.thingiverse.com/thing:636119">Cut your own gears with profile shift - OpenSCAD library</a>, modified to work with any arbitrary shape of gear tooth on a cycling tool to cut gears out from a circle, just the way gears are crafted in industry.</p><p>Put the gears_mod.scad file in a directory searchable by OpenSCAD, and put the line</p><pre><code class="language-plaintext">use &lt;gears_mod.scad&gt;</code></pre><p>in your scripts to use the library.</p><p>Refer to <a href="https://www.thingiverse.com/thing:636119">Parkinbot's design</a> for a full explanation and instructions.</p><h3>Gear cutting concept</h3><p>The concept is best illustrated by Parkinbot's video:</p><figure class="media"><oembed url="https://www.youtube.com/embed/SG3iNqUBNhQ"></oembed></figure><p>What I did was add additional tooth rack styles, and included a <code>rack_id</code> parameter in all the gear modules.</p><p>The default value rack_id=0 gives the original involute gear tooth.</p><p>Here are the additional tooth styles:</p><p><code>rack_id=1</code> - <strong>beveled sawtooth</strong></p><p>This is basically the standard involute gear tooth with beveled corners, with one side of the tooth being perpendicular to the driving force direction.</p><figure class="image"><img src="https://media.prusaprinters.org/media/prints/148595/rich_content/c829dbc4-2d27-4cf7-93b5-6baac4cae1b2/gear_tilttrapezoid_animated.gif#%7B%22uuid%22%3A%2267408d7d-c3d3-498f-83e6-b7b108f62c32%22%2C%22w%22%3A400%2C%22h%22%3A300%7D"></figure><p><code>rack_id=2</code> - <strong>sinewave</strong></p><p>The <strong>sinewave</strong> gear teeth works well for 3D printing. It has naturally round curves suitable for small teeth using a 0.4mm diameter nozzle, minimal friction due to rolling surfaces between the teeth, and more pushing surface than the semicircle teeth.</p><figure class="image"><img src="https://media.prusaprinters.org/media/prints/148595/rich_content/79703133-723f-4970-877c-57f5453b0280/gear_sine_animated.gif#%7B%22uuid%22%3A%22902c4e18-89cc-444b-9787-811581c660d1%22%2C%22w%22%3A400%2C%22h%22%3A300%7D"></figure><p><code>rack_id=3</code> - <strong>tilted sinewave</strong></p><p>I have used the <strong>tilted sinewave</strong> teeth in an application where the force is always in one direction against the teeth. Asymmetrical teeth have some sliding friction, but in practice I found these teeth to be quite smooth.</p><figure class="image"><img src="https://media.prusaprinters.org/media/prints/148595/rich_content/072ec34e-d719-4494-85e5-958c503643e6/gear_tiltsine_animated.gif#%7B%22uuid%22%3A%22a220adb0-3b2f-4829-a0bc-1aafd8db7e35%22%2C%22w%22%3A400%2C%22h%22%3A300%7D"></figure><p><code>rack_id=4</code> - <strong>semicircle</strong></p><p>These teeth are made of semicircles. They approximate a cycloid and have low rolling friction although they may want to slip apart under high loads. These teeth are easiest to 3D print also.</p><figure class="image"><img src="https://media.prusaprinters.org/media/prints/148595/rich_content/e95b95f2-6d57-4ccf-ac73-8e0030754cd3/gear_cycloid_animated.gif#%7B%22uuid%22%3A%22a72e6c50-1efd-4879-b021-29dd70c3260e%22%2C%22w%22%3A400%2C%22h%22%3A300%7D"></figure><p><code>rack_id=5</code> - <strong>cycloidal</strong> (new update, March 2022)</p><p>Cycloidal teeth have the least amount of friction because the surfaces roll against each other instead of rub. They transfer a decent amount of force without slipping. Probably overall the best kind of teeth for 3D printing. (Many thanks to <a href="/social/167780-jack/about">Jack</a> for helping me get this correct.)</p><figure class="image"><img src="https://media.prusaprinters.org/media/prints/148595/rich_content/504b6c31-a874-46c3-9eaa-4c6048164a1e/gear_cycloid_animated.gif#%7B%22uuid%22%3A%22443f860a-e035-4f6a-a762-a17b86342006%22%2C%22w%22%3A400%2C%22h%22%3A300%7D"></figure><p>&nbsp;</p><p>&nbsp;</p><p>Category: Engineering</p>