# MacTex different chapter margins in different cases

I'm totally newbie in TeX and looking for help.

I need to configure chapter styles according to requirements given by my university. It requires chapter to have top margin of 18pt and of 36pt if it is at the beginning go the new page. I figured out how to set top margin to 18pt:

\titlespacing*{\chapter}{0pt}{18pt}{12pt}


Unfortunately it does not work, as I'm using my own command for chapters:

\newcommand\Chapter[1]{
\refstepcounter{chapter}
\chapter*{
\begin{center}
\begin{Large}
\chaptername\ \arabic{chapter}. \MakeUppercase{#1}
\end{Large}
\end{center}
}
}


And it has very large spacing. I tried to use

\titlespacing*{chapter*}{0pt}{18pt}{12pt}


but it fails with error:

Missing \endcsname inserted.


So, the question is, how to make my own chapter command have different top margins if it is at the page start and if it is not? If it is not possible, just how to make it to have margins not so large?

UPD: Here's what I need to achieve: Chapter title at page start:

Chapter title somewhere in the page:

• So your chapters needn't start a new page? – egreg Feb 17 '15 at 21:15
• The argument to \chapter or \chapter* should not have any font or alignment command in it. It is supposed to be the title. The formatting of chapter titles should be specified elsewhere (either in the document class or the preamble) – David Carlisle Feb 17 '15 at 21:38
• \Large is a font switch. There is no Large environment (unless you've defined it). – cfr Feb 18 '15 at 2:23
• What do you mean by 'top margin' in the two cases? Normally, this is the margin at the top of the page, before the text body. So it doesn't apply in the middle of the page at all. – cfr Feb 18 '15 at 2:25
• @egreg Well, this is a requirement for the chapter title. And there is no requirement for chapters to start a new page every time or not. So, it is not possible to make different margins in these cases? – Ivan Feb 18 '15 at 7:59