# What is the analogue to \makechapterhead for \part?

I am formatting my thesis right now but I have problems with formatting the title page for each part of my thesis. Whereas I can access the format of each chapter using \makechapterhead and \makeschapterhead, I do not know how to access the analogue for \part. To illustrate my problem, this is what I did:

\documentclass[oneside,english,11pt,british]{book}
\usepackage[doublespacing]{setspace}

\makeatletter
\def\hrulefill{\leavevmode \leaders \hrule height 1pt\hfill \kern \z@\vspace* {-10\p@}}
\vspace*{70\p@}%
{\parindent \z@ \raggedleft \reset@font
\Large \scshape \@chapapp{} \Large \thechapter\vspace*{-25\p@}
\par\nobreak
\interlinepenalty\@M\hrulefill\newline\vspace*{-5\p@}
\LARGE \bfseries #1\par\nobreak
\vspace*{-20\p@}%
\hrulefill
\par\nobreak
\vskip 30\p@
}}

\begin{document}
\part{This is part 1}
\chapter{This is my Chapter 1}
bla bla bla
\end{document}


Obviously, I want the first page containing the title of the part to have the same format as the format of the chapter. But I have no idea how to access the default settings. Does anyone know the analogue of \makechapterhead?

I'd would like to suggest you the titlesec package. Using this package you can easily customize the sectional unit headings even without knowing the original definitions; here's an example producing the desired format both for chapter and part headings:

\documentclass[oneside,english,11pt,british]{book}
\usepackage[doublespacing]{setspace}
\usepackage{titlesec}

\titleformat{\part}[display]
{\normalfont\filleft}{\Large\scshape\partname\ \thepart\\*[-15pt]\hrulefill}{-13pt}{\LARGE\bfseries}[\vspace{-25pt}\hrulefill]
\titleformat{\chapter}[display]
{\normalfont\filleft}{\Large\scshape\chaptertitlename\ \thechapter\\*[-15pt]\hrulefill}{-13pt}{\LARGE\bfseries}[\vspace{-25pt}\hrulefill]
\titlespacing*{\chapter}
{0pt}{65pt}{40pt}

\begin{document}

\part{Test part}
\chapter{Test chapter}

\end{document}


Parts are not formatted as chapters by the standard LaTeX documentclasses, i.e. the layout of the head is not layed out to another macro. But you can go and patch the related internal. In this case it would be directly the @part macro:

\def\@part[#1]#2{%
\ifnum \c@secnumdepth >-2\relax
\refstepcounter{part}%
\else
\fi
\markboth{}{}%
{\centering
\interlinepenalty \@M
\normalfont
\ifnum \c@secnumdepth >-2\relax
\huge\bfseries \partname\nobreakspace\thepart
\par
\vskip 20\p@
\fi
\Huge \bfseries #2\par}%
\@endpart}


(Verbose from book.cls)