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Post by brianchapman on Mar 26, 2018 15:54:16 GMT -5
I'm building a TT scale (1:120) SD40 from scratch, beginning with the frame. I'm familiar with the Brian Banna frame construction method he introduced (around 2006 iirc). Also, I've just reviewed the walkway and frame built by the author of Milepost15 (I did not find his name attached to the materials I read). I have an early HO Kato SD40 and the old Athearn Blue Box SD40-2, but I am unfamiliar with what Athearn has done in frame construction in recent years.
I'm going for as much accuracy as I can possibly achieve, so providing room for under walkway details is important, so maybe the Banna frame should be my inspiration? But, I see in his YouTube build videos (watching SD40T-2 #509 series now), it appears Brian is using contemporary Athearn frames rather than those of his own design.
Got suggestions? Thanks much,
Brian Chapman
Cedar Rapids, Iowa
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Post by big train james on Mar 27, 2018 19:05:22 GMT -5
Hi Brian,
If you have all those tools available, I'd suggest building a frame from scratch. Or do the cad and get etched metal frame parts made.
Go to CPTracks.CA and register. They have several EMD drawings in their document section, including a frame drawing for the sd40. Full dimensions, sections, elevations, and plans are included in the frame drawing. It's a great resource.
Jim
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Post by brianchapman on Mar 28, 2018 4:31:25 GMT -5
Jim, hey,
Can't wait to get over to CPTracks. Thank you much for the lead.
I will build the frame from scratch, what I'm after is the best/favorite frame style/type to build.
Again, thanks!
Brian Chapman
Cedar Rapids, Iowa
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Post by big train james on Mar 28, 2018 11:13:25 GMT -5
Hmmm, well I guess I would say the best frame to build would be the real one, if you're starting from scratch.
My plan in O scale is to use a machined .0625" plate for the bottom plate of the frame. Then etched metal parts for the frame webs, end sheets, step sides, bolster extensions, steps, frame top flanges, walkways, and side sills. I haven't decided yet on the walkway braces, which are channels on the prototype. All the frame flanges and webs, plus end sheets probably, will be designed as tab and slot construction, hopefully leading to a high degree of precision.
I'd like to have the fuel tank milled out of bar stock either on a multi axis cnc machine, or a wire edm machine. I've got it drawn with the sides faceted instead of smoothly curved since in reality they are formed with a brake rather than rolled. The fuel tank should add plenty of weight down low. I'll also add cnc turned air reservoirs.
I never signed up for a different photo site after Photobucket, so can't post any pics of my cad. Let me see about posting a link to dropbox instead.
Jim
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Post by big train james on Mar 28, 2018 11:23:01 GMT -5
Dropbox link for the cad I have so far for an sd40-2. www.dropbox.com/sh/kymqzjtowftzgy9/AADCrtqiITWk0k9QcyPh_pnpa?dl=0The cad is actually done in Autocad, but I did the captures in Rhino because its basic render is better than the Autocad version. The sd40-2 project is on hold at the moment as I work on an sw1500 instead. Someday I'll get back to it. |
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Post by brianchapman on Mar 30, 2018 10:17:27 GMT -5
Jim, thanks much for your SD40-2 link. Always enjoy looking at this kind of work.
Are you using published drawings in your SD40-2 work? Your faceted fuel tank should look terrific at 1:48.
For my SD40, I've got EMD drawings from the 1966 Car & Locomotive Cyclopedia and an all views drawing from Model Railroading magazine. I'm aware of the problems that drawings can offer, but I don't live near a museum SD40. In Photoshop I resize scanned drawings horizontally and vertically to correct paper stretching in the printing process. I have Kato SD40s on hand, haven't checked measurements against published dimensions.
Also, I'm watching Brian Banna's SD40T-2 build presentation on YouTube.
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Post by big train james on Mar 30, 2018 21:32:53 GMT -5
Brian,
I'm using several different sources of information. Almost all of what I have used is publicly available. I have gotten connected to a guy that had some extra EMD drawings, like for the plow. But most of the info is on the web.
CPTracks has a bunch of EMD drawings. The sd40-2 isn't that distinct from the sd40, mostly just longer, but most parts are the same. The whole coupler pocket, for instance, is derived from the info on the CPTracks sd40 drawing.
RR-Fallen-Flags.org has a section for manuals, which includes two EMD parts catalogs, which are chock full of drawings of all sorts. Not whole frame drawings like the CPTracks ones. But all sorts of things from Blombergs to HTC's and Flexicoils, air systems, cooling systems, plows, steps, pilots, cab details, numberboards and lighting, glazing, journals, etc. Usually itemized drawings are included with the parts lists, which I can bring into cad and scale, then essentially trace. Sometimes there is some non-uniform stretching or distortion, but I can usally deal with it effectively.
Trainiax has decent drawings which I can use to a certain degree, but one of the big resources on his site is the phase information. Things like the position of the cut-out in the side sill can be found there.
Don Strack's UtahRails site has several EMD clearance diagrams under the loco notes tab. These give a nice section through the frame, bolster extensions, side sills, and air reservoirs, and an end view of the fuel tank (although it's just the end sheet, not the scalloped bottom), and indicate the pilot as well as the superstructure. These are great for positioning things like the air reservoirs properly. Between the diagram for the sd40-2 and the sd50, it covers both early and late sd bolster extension styles.
I use tons of photos, mostly from the web, but occasionally my own or those shared with a few friends. These help a lot to make sure that what I see in the drawings matches what I see in photos. I know one guy that is working on gp38-2's in p48 that has a lot of photos with tape measure included. I draw some of that stuff so that we can both use it.
Occasionally, but not too often, I will use an HO model and measure from it and scale it up to O. But I don't trust most models to be accurate unless I've got a sense from word on the street that they are. I've checked out the Details West plows, and decided they aren't actually scale. But the latest Athearn ones are pretty nice. I've measured a Cannon anticlimber and will consider doing the same with a couple other parts. I talked to Dave about doing O scale once. He wasn't too interested. Too bad as what Cannon does would still be super relevant in O scale even as RTR HO models have gotten so good that not as much Cannon work needs to be done. Anyway, it's just another way to get info. Except you end up with a bunch of HO parts when you're in a different scale, that you don't really need after the fact. The price of glory, I guess.
Lots of information is available from some of the historical societies, but figuring which one has what can be a pain, and many of them have content that would be helpful but lack the human and/or financial capital to get the stuff cataloged. The N&W site is pretty good, with a lot of info seachable on line.
Hope that helps. If I think of anything else, I'll edit this post or add a new one.
Jim
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Post by brianchapman on Mar 31, 2018 9:26:12 GMT -5
Alright, Jim, your post has been printed and put into my SD40 binder. Darn nice of you to take the time to present all that information. Very helpful, and I much appreciate it.
I understand what you're saying about O scale parts. The HO guys complain about the dearth of Alco parts in their scale, and Dave Hussey, I believe, has said he's not much interested in pursuing that parts angle.
-Brian
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