How to build a T3 - Part 2
Step 3: The Mock-up
It's by no means essential, but I usually find it a good idea with a complicated model like a steam loco to make a "mock-up," representing the main structural elements with simple shapes that I can add detail to later on.
Very useful at this stage is a spreadsheet set up to make box shapes. See the User Guide for how to do this.
The T3 has inside frames, which also form the sides of the well tank. This is nice - we don't have to bother about "daylight under the boiler." The frames/tank can be a simple box with H running from 24 to 112, L from 106 to 780, and width about W = +/- 55 (the drawings don't clearly show the lateral position of the frames, but we know that they must fit inside the back-to-back dimension of the wheels).
The footplate sits on top of the frames. It runs from L=66 to 796, and W= +/- 111. We can make it 6cm (two R3D units) thick. (The part of the footplate under the cab and bunkers is wider, but we can worry about that later.)
The cab sits on the footplate, with length 593 to 796, width +/- 130. The bottom of the curved roof is at 324.
The bunkers sit on the footplate ahead of the cab, with their front ends at L=492 and tops at H=221. The outside edge is flush with the cab, and the inside at W=80. Of course, we only need to make one and use Reflect W to copy it to the other side.
The boiler centreline is at H=186, and it runs from 116 to 618. We're not talking Swindon here: it's the same radius all along, 60cm. We can knock this up quickly with the cylinder tool, then put in the details of firebox and smokebox later. We might as well use a lot of steps to make the cylinder, as the boiler is a large and conspicuous part.
Tidying up
Before going any further, it's a good idea to set all the parts we have made so far to D3D only with the [D3D] modifier. We can "rescue" those we need for BIM view later.
The result doesn't look much like a loco yet, but everything seems to be in roughly the same proportions as the drawings, so we seem to be on the right lines.
Download the STK file with the mockup.