This post is for reader Roy, who asked how the triple expansion engine columns and base and cylinder blocks were aligned, and also about joint sealants.
To be honest, I did not really remember the details, but the posts on or close to Feb 2015 include the following photos. The aluminium plates were precisely machined keep the column faces exactly separated by the final width. The plates were bolted to the columns, then to each other. I lined up the join in the plates with the center of the main bearing housings in the base plate.
The longitudinal alignment with the cylinder bores was determined by the precise drilling in the tops of the columns, and the cylinder base covers. And a little longitudinal movement in the crankshaft allowed for a few thou discepancy.
And this is what I used to steam proof the joins. I used no gaskets. The Loctite 567. It was recommended by an expert friend who uses it on full size steam engines (thanks Tom!). The Loxeal 58.11 is also excellent but it sets very hard, and is very difficult to separate later.