Some of my modelling updates of late have been a little.... short (mainly because I've taken to shewing my works on a model railway forum too.... and I tend to go into great detail there, which takes ages, then get a little bit of 'but I've done this once...' when I come here to shew it again).
So to redress that balance, I'll go into a little more depth now.
I bought an old Ratio Johnson Midland 4-4-0 kit off of ebay. It is rather like the old Kitmaster/Airfix/Dapol plastic locomotive kits (I think the closest currently-available look-a-like would be the Dapol City of Truro). Sadly it's been out of production for many, many years (if you want to buy a new one, start badgering Peco, who own Ratio...)
What I want to build, however, is a Pollitt 4-4-0 of the Great Central Railway (LNER class D6
There are a few differences that immediately jump out between the two:
-1) The GCR loco has a Belpaire firebox (like a cubiform shape with curved edges) whilst the Midland engine has a round-topped firebox with a rather ornate safety valve cover.
-2) At the other end of the boiler, the GCR loco has a noticeably longer smokebox, a slightly longer boiler barrel and a different set of frames.
-3) The cab is more enclosed on the GCR loco.
-4) The GCR loco is much wider (the boiler might even be larger in diameter).
Now I'm not working off a drawing of the D6, but I do have a couple of good photos that provide enough information for a decent attempt at a kit bash. In any event, my scratchbuilds don't purport to be millimetre-perfect, but rather attempt to capture the salient points of the prototype (to varying measures of success).
Now then, how did I do it?
I built the chassis as-per the kit, and fitted slightly larger driving wheels (7' diameter, rather than 6'6'').
I then moved onto the body. Beginning by gluing the two halves together, this gives a complete boiler, complete smokebox and two cab sheets. Now then, cut the boiler just behind the smokebox and sand off all of the detail (handrails, boiler bands- the lot). Cut the sides of the smokebox away to leave just the smokebox front. Be careful however not to damage the chimney. On the boiler, cut around the dome and lift it out (it helps to cut away some of the boiler too, and sand back until you have the dome on its own).
Cut into the boiler just behind the first boiler band working forwards from the cab. Extend the cut down until the boiler is half-way cut through, then cut back along the boiler until you reach the cab. Now take some 0.5mm plastic sheet and cut three rectangles- one the length you've cut out and the width of the boiler (around 19mm by 17mm) and the other two the length of the cut-out by the depth of the gap (around 19mm by 9mm). Glue these together to form a U-shape, then glue into the boiler where you cut the top away. Then give this a wrap of paper. It should look like a Belpaire firebox...
Now cut a strip of paper 63mm wide, and wrap that around the boiler. Cut away where the paper fouls the wheel splashers (it doesn't matter if the boiler wrapper simply cuts square across at this point- simply use milliput to fill in later). Push the smokebox front into the new boiler wrapper (the boiler wrapper will need to be cut at the bottom to get it in).
Now cut two strips of paper 15mm wide and wrap them around the boiler wrapper at the smokebox end. This creates the new smokebox wrapper.
Then take some 0.5mm plastic sheet and cut overlays for the cab and the splashers. We are looking to build up these parts to the thickness of the bottom of the splashers (which are 1mm wider on both sides). This is complicated- because of the curved shape- so what I did was to try to cut slightly oversize and then carve back with a scalpel. Where I cut undersize there was little to be done except to go back with milliput later and fill in the gaps. You can either cut four overlays (by which I mean, the splashers and cab sheets are combined) or eight (by which I mean, the splashers are separate to the cab sheets). I opted for the latter, to make life slightly easier for myself, and moulded the two together with some milliput later.
Now you can glue the front of the running plate into position, and you will find that the smokebox doesn't fit into the slot cut for it. This doesn't matter however, as we need to make new frames- cut some plastic sheet around 30mm in length and 3mm in height, then shape so as to flow into the splashers at the rear, with a diagonal edge to the front. Behind the smokebox, the frames reduce in height by around 1mm. This is all much simpler to actually do than it is to describe!
If you've somehow managed to follow these instructions, you should end up with something a little like this:
This is mine, after I filled in all the gaps.... it still needs sanding back....
Now for the tender, you can build the example in the kit (it is more or less the right size), but I'd be inclined to leave the top off, because that bit isn't quite right and has ghastly moulded coal. Much better to use some scraps of plastic sheet and scratchbuild the tender tanks.... it will also need the moulded lining bands removed and the coal rails replaced.
It is a nice model though and certainly looks the part, as can be seen: