\section{Machinery for Assembly and Gluing}
To dispense the glue in and on the  raakvlakken of the tubes we developed a gluing machine based on the concept described in~\cite{mpi-glue}. The glue is always distributed on the tubes in the combs on the granite table.
The distribution of glue is illustrated in Fig.~\ref{gludist}, showing 
a cross section of a few tubes in a multi-layer.
\begin{figure}[tpbh]
\begin{center}
\setlength{\unitlength}{1cm}
\begin{picture}(14,14)
\put(0,0){\mbox{\epsfysize=14cm\epsffile{gludist.eps}}}
\end{picture}
\end{center}
\label{gludist}
\caption{\sl Glue distribution between tubes in a multilayer.}
\end{figure}

 In between tubes that neighbour
 horizontally, we use the thin glue
 Araldyte-DP2019 which nicely distributes itself in the 65~\um space..
 To glue  the tubes between vertically neighbouring tube layers we use Araldyte-2011 which is more viscous and remains it shape 
until the tube-layer already on the spacer is pressed on it by gravity. 



The chamber and cross-plate sag during glue curing is reduced by a sag-compensation system. The positioning of the spacer and the tubes glued to it is constantly monitored by RASNIK systems.

\subsection{Sag Compensation}
The cross-plate sag amounts up to 50~\um when freely suspended and affect the 
relative wire positions. The chamber sag affects the relative tube position
and amount 0.8~mm 'in the air'. Both sags are removed by the sag compensation system. the system supports the longbeams wich are attacthed to the cross-plate at the Bessel points. This allows to reduce the sag with typically 90%. 

To be able to reach this value we added 10~kg weigths to the 'ears' on the cross-plates. These additional weigts also force the spacer to 'seek' its position on the sphere holders.

The system consists of 4 pneumatic tower-pairs. Each pair carries a
cross-bar that supports the two longbeams
at a specific position. We use a pair near the outer cross-plates and we use
 a pair on each side of the middle cross plate. figure~\ref{sagcomp} shows two towers  on the ref-side at the middle cross-plate, which form indivudally two pairs with their corresponding towers at the non-ref side of the chamber.

\begin{figure}[tpbh]
\begin{center}
\setlength{\unitlength}{1cm}
\begin{picture}(14,14)
\put(0,0){\mbox{\epsfysize=14cm\epsffile{sagcomp.eps}}}
\end{picture}
\end{center}
\label{sagcomp}
\caption{\sl Two sagcompoensation towers at the middle cross-plate.}
\end{figure}

