Once again the drawings in Model engineer are wrong and if you are making the super heated version of this loco to magazine articles you need to be aware. It isn’t helped by the fact that dimensions are spread around various drawing published in different issues. If you make the chests in part 8 by the time you get to the lubricator plumbing in part 13 you’ll be doing them again or adding the lubricator pluming differently.

The steam chest drawing (item 31) in Part 8 has a number of dimensions missing

1) thickness nears bolting face (with exhaust port) = 1/4″
2) width of cavity 9/16″
3 outside wall thickness 3/16″
4) centreline 17/32″ from bolting face

Other hole locations are given in item 42 also in Part 8.

If you are doing the superheater version you can’t put the inlet port on the center line. By the time you get to Item 100 in issue 13 the lubricator banjo mount is shown to 5/16″ inboard of the the inlet port. If you drill the 3mm hole for the 4BA tap it will go right through the rear inboard stud hole. See attached pdf, I’ve moved the inlet port and lubricator banjo 1/16″ outboard. The inlet doesn’t need to be in line with the valve rod as it doesn’t reach that far back on the rearward stroke.