\def\w{\ht\cals@current@row=50pt\relax}
\def\mktable{%
\begin{calstable}[n]
\colwidths{{70pt}{80pt}{90pt}}
\def\cals@framecs@width{\cals@cs@width}
\def\cals@framers@width{\cals@rs@width}
\setlength{\cals@paddingR}{2pt plus1fil}
\brow \nullcell{ltr} \cell{b} \cell{c} \w \erow
\brow \nullcell{lrb}\spancontent{a,d} \cell{e} \cell{f} \w \erow
\brow \cell{g} \cell{h} \cell{i} \w \erow
\end{calstable}
}

\showboxdepth=2
\hsize=400pt

\setbox0=\vbox{%
\leftskip=50pt\relax
\mktable}
\showbox0
\box0

\begin{center}
some text\\
\setbox0=\vbox{%
\mktable}
\showbox0
\box0
\end{center}

\begin{flushright}
some text\\
\setbox0=\vbox{%
\mktable}
\showbox0
\box0
\end{flushright}
