<p>Designing gears is very difficult for a variety of reasons. Let me list what you should take into account:</p>

<ol>
<li><p>The shape of the teeth are very peculiar, trapezoid shape will not work as the meshing will not be constant. Exact shape is controlled by the pressure angle</p></li>
<li><p>In lower number of teeth, teeth shape must be modified to avoid any locks, these are called cutoffs</p></li>
<li><p>Reducing the amount of material to print requires careful design, most people simply place circles but they cause weak points.</p></li>
<li><p>Herringbone and double herringbone gears improve meshing but are even more difficult to design.</p></li>
</ol>

<p>For the reasons stated above, creating gears by hand is next to impossible without special tools. Luckily for those who are searching for it, there are systems that generate gears for 3D printing. This <a href="https://www.thingiverse.com/thing:1427458" rel="nofollow noreferrer">customizer</a> has many options and is very open about the licensing, which is another issue with many scripts. For example, it is explicitly forbidden to print parts imported from the McMaster-Carr Catalogue.</p>

<p>If you use OpenSCAD, <a href="https://www.thingiverse.com/thing:1427673" rel="nofollow noreferrer">this library</a> can create racks to go with the gears.</p>

<p>The parameters of the customizer are explained in the page. The script also contains explanations of every module and function.</p>

<p>Disclaimer: Both scripts are mine, yet I do not earn anything when people use them. I created the library when I was unable to find the gears I needed, published with a relaxed license to help others.</p>

CC BY-SA 4.0
2019-02-01T22:03:48.827Z
@CarlWitthoft Comments are transient and aren't meant for answers to the question. This would be better as a more detailed answer, explaining a little bit about the customizer.
Tom van der Zanden
CC BY-SA 4.0
2019-02-02T16:17:41.690Z
Added more explanation about the process of creating gears. Better?
Cem Kalyoncu
CC BY-SA 4.0
2019-02-02T17:21:14.887Z
@TomvanderZanden *bump for Cem*
Trish
CC BY-SA 4.0
2019-02-03T18:36:58.517Z
@CarlWitthoft you had said something that was adressed, so I bumped you for Cem :P
Trish
CC BY-SA 4.0
2019-02-01T06:07:41.713Z
2019-02-02T17:26:14.710Z
2019-02-02T17:26:14.710Z
Cem Kalyoncu
<p>There are also several <a href="https://geargenerator.com/" rel="nofollow noreferrer">gear generators</a> out there. Correct gear geometry is important for long life and noise reasons. </p>

<p>One thing to keep in mind is that iff you are able to print accurate gears it's easy to print <a href="https://en.wikipedia.org/wiki/Herringbone_gear" rel="nofollow noreferrer">herringbone gears</a> which are not easily machinable with other techniques.</p>

<p>That should cover the how (use a generator and import the geometry). The "is it possible" depends on your 3d printing skills, if possible you need to be able to do 0.1 mm tolerances, elephant footing will make the gear unusable.</p>

<p>That said I was able to print some planetary gears 'in place' (ie. assembled on the print bed) using a raft to avoid fusion of the lower layers:</p>

<p><a href="https://i.sstatic.net/5XYIT.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/5XYIT.jpg" alt="left: printed with raft, right: printed on build plate"></a></p>

<p>Spinning the gear printed on raft: <a href="https://i.sstatic.net/MdfuZ.jpg" rel="nofollow noreferrer">https://i.sstatic.net/MdfuZ.jpg</a>
Spinning the gear without a raft directly on the print bed: <a href="https://i.sstatic.net/rQ72S.jpg" rel="nofollow noreferrer">https://i.sstatic.net/rQ72S.jpg</a></p>

<p>The first one is still on my work desk as a fidget spinner because it spins so nicely ;-)</p>

CC BY-SA 4.0
2019-02-01T15:55:33.750Z
Can you explain the term " elephant foot"  ?
Carl Witthoft
CC BY-SA 4.0
2019-02-02T17:00:45.923Z
Sure! It's when your first layers squash out. Mostly that's caused by too low nozzle height or to high bed temperature.
fho
CC BY-SA 4.0
2019-02-02T17:21:28.030Z
Example pictures and solutions: https://www.google.com/amp/s/m.all3dp.com/2/elephant-s-foot-3d-printing-problem-easy-fixes/
fho
CC BY-SA 4.0
2019-09-18T18:33:44.530Z
I bought a program to make gears and chain gears, but this one looks great!
Fernando Baltazar
CC BY-SA 4.0
2019-02-01T09:31:37.170Z
2019-02-01T15:55:10.693Z
2019-02-01T15:55:10.693Z
fho
<p>I want to create a micromouse project for fun that use 2 20&nbsp;mm&nbsp;x&nbsp;8.5&nbsp;mm (0.8&nbsp;mm shaft) motors. I have my own PCB as base. I want its built-in gears will be attached to two 3D-printed wheels with gears at the back of the wheels at each side. I'm having hard time to start designing the gears since I couldn't find any tutorial.</p>

<p>(photo for reference and not mine)
<a href="https://i.sstatic.net/ady1o.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/ady1o.jpg" alt="enter image description here"></a>
<a href="https://i.sstatic.net/3JM9F.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/3JM9F.jpg" alt="enter image description here"></a></p>

<p>My Question:</p>

<ol>
<li>How to design the gears at the back of the wheel? (I use Sketchup)</li>
<li>Is 3d-printing such small objects possible?</li>
</ol>

CC BY-SA 4.0
2019-01-31T22:23:32.027Z
designing is engineering. Is printing possible is here.
Trish
CC BY-SA 4.0
2019-02-03T00:07:44.277Z
About gear geometry: https://www.youtube.com/watch?v=Q-XOM4E4RZQ
Trish
CC BY-SA 4.0
2019-02-04T08:58:37.920Z
I would use OpenScad and probably a library to do this.
E Doe
<3d-models><3d-design>
How to design gears
Dave Benemerito
# How to design gears

(Asked by: username_0 on 2019-01-31)

I want to create a micromouse project for fun that use 2 20 mm x 8.5 mm (0.8 mm shaft) motors. I have my own PCB as base. I want its built-in gears will be attached to two 3D-printed wheels with gears at the back of the wheels at each side. I'm having hard time to start designing the gears since I couldn't find any tutorial.

(photo for reference and not mine)
[![enter image description here](https://i.sstatic.net/ady1o.jpg)](https://i.sstatic.net/ady1o.jpg)
[![enter image description here](https://i.sstatic.net/3JM9F.jpg)](https://i.sstatic.net/3JM9F.jpg)

My Question:

1. How to design the gears at the back of the wheel? (I use Sketchup)
2. Is 3d-printing such small objects possible?

**Tags:** 3d-models, 3d-design
> **Comments:**
> **username_1**: designing is engineering. Is printing possible is here.  
> **username_1**: About gear geometry: https://www.youtube.com/watch?v=Q-XOM4E4RZQ  
> **username_2**: I would use OpenScad and probably a library to do this.  

---

## 2 answers

### Answer by username_3 on 2019-02-01. Score: 4

Designing gears is very difficult for a variety of reasons. Let me list what you should take into account:

1. The shape of the teeth are very peculiar, trapezoid shape will not work as the meshing will not be constant. Exact shape is controlled by the pressure angle
2. In lower number of teeth, teeth shape must be modified to avoid any locks, these are called cutoffs
3. Reducing the amount of material to print requires careful design, most people simply place circles but they cause weak points.
4. Herringbone and double herringbone gears improve meshing but are even more difficult to design.

For the reasons stated above, creating gears by hand is next to impossible without special tools. Luckily for those who are searching for it, there are systems that generate gears for 3D printing. This [customizer](https://www.thingiverse.com/thing:1427458) has many options and is very open about the licensing, which is another issue with many scripts. For example, it is explicitly forbidden to print parts imported from the McMaster-Carr Catalogue.

If you use OpenSCAD, [this library](https://www.thingiverse.com/thing:1427673) can create racks to go with the gears.

The parameters of the customizer are explained in the page. The script also contains explanations of every module and function.

Disclaimer: Both scripts are mine, yet I do not earn anything when people use them. I created the library when I was unable to find the gears I needed, published with a relaxed license to help others.

> **Comments:**
> **username_4**: @CarlWitthoft Comments are transient and aren't meant for answers to the question. This would be better as a more detailed answer, explaining a little bit about the customizer.  
> **username_3**: Added more explanation about the process of creating gears. Better?  
> **username_1**: @TomvanderZanden *bump for Cem*  
> **username_1**: @CarlWitthoft you had said something that was adressed, so I bumped you for Cem :P  

---

### Answer by username_5 on 2019-02-01. Score: 3

There are also several [gear generators](https://geargenerator.com/) out there. Correct gear geometry is important for long life and noise reasons.

One thing to keep in mind is that iff you are able to print accurate gears it's easy to print [herringbone gears](https://en.wikipedia.org/wiki/Herringbone_gear) which are not easily machinable with other techniques.

That should cover the how (use a generator and import the geometry). The "is it possible" depends on your 3d printing skills, if possible you need to be able to do 0.1 mm tolerances, elephant footing will make the gear unusable.

That said I was able to print some planetary gears 'in place' (ie. assembled on the print bed) using a raft to avoid fusion of the lower layers:

[![left: printed with raft, right: printed on build plate](https://i.sstatic.net/5XYIT.jpg)](https://i.sstatic.net/5XYIT.jpg)

Spinning the gear printed on raft: <https://i.sstatic.net/MdfuZ.jpg>
Spinning the gear without a raft directly on the print bed: <https://i.sstatic.net/rQ72S.jpg>

The first one is still on my work desk as a fidget spinner because it spins so nicely ;-)

> **Comments:**
> **username_6**: Can you explain the term " elephant foot"  ?  
> **username_5**: Sure! It's when your first layers squash out. Mostly that's caused by too low nozzle height or to high bed temperature.  
> **username_5**: Example pictures and solutions: https://www.google.com/amp/s/m.all3dp.com/2/elephant-s-foot-3d-printing-problem-easy-fixes/  
> **username_7**: I bought a program to make gears and chain gears, but this one looks great!  

---

