how to make a cog/gear in LaTeX?

Question

I was wondering what would be a good way to make this in LaTeX. Basically, what I want to do with this is use it as a chapter heading. So basically it will be something like this:

cog chapter # Chapter name

What would be the best way to achieve this? Am I better off using the image or making it myself?

Thanks a lot for you time!

EDIT: I have done what the comments have recommended but I am having difficult implementing the gear into the chapter heading using titlesec. Here is the MWE:

\documentclass[12pt]{memoir}

\usepackage{tikz}
\usepackage{titlesec}


% #1 number of teeths
% #2 radius intern
% #3 radius extern
% #4 angle from start to end of the first arc
% #5 angle to decale the second arc from the first 

\newcommand{\gear}[5]{%
\foreach \i in {1,...,#1} {%
  [rotate=(\i-1)*360/#1]  (0:#2)  arc (0:#4:#2) {[rounded corners=1.5pt]
             -- (#4+#5:#3)  arc (#4+#5:360/#1-#5:#3)} --  (360/#1:#2)
}}  

\titleformat{\chapter}{\Huge\bfseries}{\usebox{\gear{18}{0.5}{0.4}{10}{2}}\thechapter}{20pt}{\Huge\b‌​fseries}

\begin{document}
 \begin{tikzpicture}
   \draw[thick] \gear{18}{0.5}{0.4}{10}{2};
 \end{tikzpicture} 

\chapter{Whatever} 

\end{document} 

EDIT 2: With the help of @Qrrbrbirlbel and @StefanKottwitz I have gotten the following:

\documentclass[12pt]{memoir}

\usepackage{tikz}
\usepackage{titlesec}

\newsavebox\gearbox
\newcommand{\gear}[5]{%
\begin{tikzpicture}
\draw[ultra thick]
\foreach \i in {1,...,#1} {%
  [rotate=(\i-1)*360/#1]  (0:#2)  arc (0:#4:#2) {[rounded corners=1.5pt]
             -- (#4+#5:#3)  arc (#4+#5:360/#1-#5:#3)} --  (360/#1:#2)
};\end{tikzpicture}}
\sbox\gearbox{\resizebox{!}{2em}{\gear{18}{2}{1.6}{10}{2}}}
\titleformat{\chapter}{\Huge\bfseries}{\usebox{\gearbox}\thechapter}{20pt}{\Huge\bfseries}

\begin{document} 

\chapter{Whatever} 

\end{document} 

But I would like to have the gear look more like this and have the gear behind the chapter number. How can this be done?

Answer 1

Before you can use the box, you need to store your gears within, such as

\newsavebox{\chaptergear}
\savebox{\chaptergear}{%
  \begin{tikzpicture}
    \draw[thick] \gear{18}{0.5}{0.4}{10}{2};
  \end{tikzpicture}}
\titleformat{\chapter}{\Huge\bfseries}{\usebox{\chaptergear}%
  \thechapter}{20pt}{\Huge\bfseries}

Answer 2

Here is a quick gear construction with a single path so you can fill it properly. I will try to come back to this to make it with a proper key=value syntax. Right now it's only boring \definitions. But if you have a different thread profile the idea is essentially the same.

\documentclass[tikz]{standalone}
\usetikzlibrary{calc}
\begin{document}
\begin{tikzpicture}
\def\teethnumber{17}     %<--- How many teeth
\def\threadheight{1mm}   %<--- How high the thread
\def\outrad{5mm}
\draw[fill=gray,even odd rule] 
let 
\n{dpt} = {360/\teethnumber)}%deg per teeth %<--- Overkill! Can be defined outside
in
(0,0) circle (4mm)                          %<--- Shaft circle
({\n{dpt}*(0.5)}:\outrad) \foreach \x in {1,...,\teethnumber}{ %<--- Tooth covers half width
arc ({\n{dpt}*(\x-0.5)}:{\n{dpt}*(\x-0.25)}:\outrad)  %<-- Lower arc
--++(\x*\n{dpt}:\threadheight)                        %<-- Go up
arc ({\n{dpt}*(\x-0.25)}:{\n{dpt}*(\x+0.25)}:\outrad) %<-- Upper arc
--++(\x*\n{dpt}:-\threadheight)                       %<-- Go down
arc ({\n{dpt}*(\x+0.25)}:{\n{dpt}*(\x+0.5)}:\outrad)--%<-- Get to the next one for cont. path
({\n{dpt}*(\x+0.5)}:\outrad)
};
\end{tikzpicture}
\end{document}

A few examples starting from the given code

Last one is done by making the shaft circle larger than the outer radius. Which might be beneficial for planet gears and whatnot....

Answer 3

I was using several material: the answer of Stefan Kottwitz here, and the amazing macro of Alain Matthes to create a gear.

Mixed together with a bit of fine tuning it gives something like this:

\documentclass[12pt]{memoir}
\usepackage{tikz}
\usepackage{titlesec}

% #1 number of teeths
% #2 radius intern
% #3 radius extern
% #4 angle from start to end of the first arc
% #5 angle to decale the second arc from the first 

\newcommand{\gearmacro}[5]{%
\foreach \i in {1,...,#1} {%
  [rotate=(\i-1)*360/#1]  (0:#2)  arc (0:#4:#2) {[rounded corners=1.5pt]
             -- (#4+#5:#3)  arc (#4+#5:360/#1-#5:#3)} --  (360/#1:#2)
}}  

\newcommand{\chaptergear}{\begin{tikzpicture}
   \fill[gray] (0,0) circle (2cm);
   \draw[thick,rotate=12,fill=gray] \gearmacro{8}{2}{2.4}{20}{2};
   \draw[thick,fill=white] (0cm,0cm) circle(1.35cm);
 \end{tikzpicture}}

\newsavebox\gearbox
\sbox\gearbox{\resizebox{!}{5em}{\chaptergear}}
\titleformat{\chapter}{\Huge\bfseries}{\raisebox{-0.75cm}{\usebox{\gearbox}}\hspace*{-1.25cm}\thechapter\vspace{\stretch{-10}}}{45pt}{\Huge\bfseries}

\begin{document}
\chapter{Whatever2}
\end{document}

Which gives you

I have to admit that I am not very happy with the manual tuning for putting the chapternumber in the middle of the gear, but unfortunately I do not know how to circumvent that.