I have done similiar work in the past on WW1 aircraft:
http://mwmiller.net

The first step (obviously) is to select a locomotive to model. This is a particularly important question because i think I will only have the energy for one project like this.
A steam locomotive is a ridiculously complicated machine.
I figure it will take a couple of years

My first choice was a NYC J3
i just love the looks of this machine and it has the additional benefit of being easily turned into a J3a.
But, the biggest problem is adequate refernce material. I have the kalambach book.
and, better yet, I own a copy of the 1950-52 locomotive Cyclopedia.

on the J3:
I have found a nice side view and x sections as well as a plan of the boiler alone - also a very nice set of plans for the Baker valve gear.
I'm sure there is more useful stuff in the Cyclopedia - i just need to find out the brand names of all the components
Btw - I also contacted the guy who created the J3 DXF file on Steamcad, and he ok'd the use of his drawing for the purposes of creating a 3D model.

But, the idea is to get down to bolt level.
and i can see that i will not have enough data.

So I have started to think that it would be smarter to chose a locomotive that i can look/see/measure.
i live in Danbury CT so I could get to the Valley RR fairly quickly
they operate a 2-8-0 and a 2-8-2
yeah - it's the smart thing to do
But still - the J3 is such a beast

so... I have some questions

- Where can I find additional data on the J3
- Which forum would be best for me to ask technical questions concerning locomotives.

and
If you could only model one steam locomotive which one would you chose?

and that's not just a hypothetical question ;-)
TIA
Mark Miller