Having assembled both chimney units completely in my garage before bringing them to site, I was confident that things should go together without mishap. (Odd how it's the one thing you didn't check that comes back to bite you!).
The tubes are numbered from One to Four as Left Front, Left Rear, Right Rear to Right Front. Each tube had been labelled with the corresponding number of Centre Pop 'pips' (really useful if you can find them again!)
|Number One Tube in place|
|Numbers One & Two|
|Numbers One, Two & Three|
|Numbers One to Four all in place|
|View from Above|
|Exhaust Steam Pipe to Numbers Three & Four Tubes|
|First Heat Shield around numbers One & Two Tubes|
The left and right hand pairs of tubes converged so much that the second shield could not be fitted using the standard mounting method.
After removing the heat shield again, the measured gap between the tubes at their lower end was 5" but only 4.25" at their upper end. Clearly this would not be acceptable (and definitely not a problem that would be encountered on a single engined Sentinel loco!).
In many of the above photos, I've endeavoured to ensure that the vertical strap behind the chimneys holding the two halves of the cab front together is dead upright. As the photos progress, the leaning inwards of the left hand chimney tubes begins to be more obvious.
Now it's going to be a bit of a grind to make the LH tubes upright and parallel to the right hand ones.
Oddly, by rotating tube number two 180 degrees, the leaning is less so it would appear that the part of the tube which fits over the base casting is not quite in line with the tube's axis. However, that is not much help as the mounting holes don't align with it that way round, hmmph!
At one point, I had thought that tightening down the superheater might have distorted the boiler top plate and made the tubes lean inwards. No such luck - life is never that easy!