That's where I may be able to help, I'm not too bad on the 3D CAD, so could knock some up with the appropriate info. Are you, by any chance, the person who bought the Diesel Loco Cyclopedia last week off ebay?
No fraid not, not me, bought mine along with the steam one states side about 20 years ago, there's a good drawing of a Blomberg B in there but I don't have any 'specific' drawings for Flexicoils or HTC for the SD40s or more modern Hi Ads for SD70s etc, only what comes in the loco three views in Diesel Era.
I have no fear of 3D CAD work (it was my second job for nine years) what I don't have is time, so if you want to dive in with the 3D printing then fill your boots and I'm sure we can work something mutual out, it'll leave me time to work on the etch art work. I had planned to make the side frames as 3D printed, then cast in resin from that, not sure how to incorporate the rear beam as its integral with the side beams. Mind that depends on how complex the 3D printed side frames are for casting or how cheap/quality they are. If the quality is good with alittle clean up and the price cheap enough then I see no reason to simply use the 3D printed sample. I'd also figured on dummy traction motors, at least on the inner axles as it is very visible 1:1 3 axle trucks, but probably as rear end only so drive would effectively be B0+1 1+Bo but that's a mile down the road.
Other 3D print parts but not resin casted from 3D would be things like MU receptacles, hoses?, light fittings, AC roof packs etc. Dynamic blisters could be 3D printed and then resin cast with etch grills and overlays. Fuel tanks could be brass but something that size is awkward to roll and bend up accurately and consistently so may opt for one master and then resin but make it hollow for a speaker etc, same for air tanks, cast in resin would be fine, I've zero issue with multimedia models, some items are often best produced in other materials than brass or white metal I feel.
The rest is probably best from etchings which I'm going to pick at this week and on holiday, first off with cabs, blower ducts, bonnets, anti climber and step wells etc, maybe some fan casings, dynamic and radiator.
Scale is going to be 1:48, silly not too, I'd of prefered S7 but then you're limiting your world to a minority of one. Whether its PROTO 48 for myself I haven't decided, I can worry about that later. First loco, well I want something that sounds good, for me the sound rates as 60% of the project so your looking at F units, GP9, GP15, GP38/40 or SD9, SD24, SD40 or SW1500, MP15.
Your cards on the table are already the tunnel 40 so that'd make sense to start with the SD40 frame and work from there....but don't be surprised if I suddenly pop up with etches for a chop nosed SD24 or something LOL. As for which Railroad?, well I'm an out West fan
so any of those will do, but mindful of light packs and local variants of course.
Etch material, the Class 40 bogie is 0.375 NS (15 thou) so I'm waiting to see how that performs for soldering, etching and bending and strength wise but think it'll be ok for cab modules etc, might cost a little more but I think it might be worth it, as I say the Class 40 bogies will be the test pieces for that material.
So just to get the party going for y'all who have no clue what we're babbling on about
MP15AC
D&RGW standard nose tunnel 40, I love the bridge in this shot! I have just got to have one of these.
Blood nose snoot tunnel motor
And now in UP hands Ex SP snoot tunnel motor.
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