The online magazine on the history and operation of vintage scale model trains in American OO gauge

Sunday, November 20, 2016

Building SD40s and also a U23B in American OO, Part II: Progress report

Back some nine months ago I had an article (more here) on starting a project that used a pair of 3D printed EMD cabs as part of kitbashing an approximation of the EMD SD40 prototypes. With further background being that there are a few 3D printed parts for American OO 1:76 scale on Shapeways (more here). 

In addition, I also purchased through Shapeways a GE cab to use to make an approximation of a U23B. As I have not described that model at all yet (other than teasing it in part I), a few details are in order. It was a conversion proposed years ago in The OO Road by Bill Johann as a relatively simple “good enough” conversion. The hood and visible portion of frame are taken from a vintage Athearn (“blue box”) GE U33C body. Some details are off, of course, but are similar to the correct details for the U23B. The hood itself is OO width, so the key issues were to shorten it slightly in length and to additionally raise the height to match the cab.

The original frame (lower part of body casting, actually, not the metal Athearn frame) was saved and widened, and a drive was no concern as I planned from the start to build it as a dummy.

The trucks are ones I had on hand, modified originally to use on a Schorr F-3, but then I obtained a pair of Schorr trucks for it, so they were available for this model. These are actually the unpowered rear trucks from TYCO GP20 models (!), widened to OO and with new wheelsets. They are the correct length for OO, and I worked out a way to use the original mounting. I also used the fuel tanks from a couple of these models, spliced together for length, they are a little small but believable. For those wondering, some prototype U23B models were built with EMD trucks, trade in trucks from F-3’s and the like, it is a nice look.

The SD40s on the other hand are built on the visible parts of the frames and the drives from two Athearn SD45T-2 models. The length worked out nicely to give convincing porches in relation to the hood used in the kitbash and the 3D printed cabs, without modifying the frame. The frames/hoods on these models come off and on using the same lugs as the original models. Couplers are underset shank Kadee couplers and are a bit low….

The solution on that will be to mount the rear U23B coupler low to match the SD40s and mount the front coupler at the correct height, it will run as the trailing unit. As to mounting the hood on the U23B model I will work out a way that the hood is held on the frame with screws rather than gluing it on as I did with the SD40 models.

While they look pretty good, big picture there are some significant compromises on all three models. One special bummer is that the 3D cabs have some rough surfaces. I was hoping after the bath in Bestine (needed to prep for painting) that they would be smoother, but really they are about the same. I will try to be optimistic that the paint will help level out the rougher side surfaces but realize it will only help so much. I think this may simply be a consequence of the cabs all being scaled up from models developed for smaller scales, although perhaps they were not printed well either.

In any case I have the drives setup now for the SD40s and one body mounted on the frame as of this writing. Compared to the scale drawing the major dimensions are pretty much there, but a lot of specific details are off.

The three Diesels are a big project but good ones for this fall which has been busy for me. I do a few small things on them one day and then puzzle over them and then a few more small things another day. There are still details to sort out, but I think I pretty much have the issues planned out. They will all have for example a modified, “modern” paint scheme for my Orient that is driven by needing to paint the cab with a different type of paint than my standard paint I use on plastic.

The next big thing to do is add handrails, I need them on before painting.

As already noted, there are a lot of compromises on these models. Back to the handrails, for example, with all the other things that are a bit off I don’t see a big reason to not just use the original HO handrails. So I will, modifying the end handrails to have the chained off opening in the middle compared to the original Athearn design. It is visually more important that they just match on all three models rather than being exactly correct.

I hope these models come out well but as of this moment I am not real sure of the result, the compromises have me a little worried but hoping still for “good enough.” They should match the modern cars I have from Johann pretty well at least, so that part is good. I will get them done and do my best, I have been pleasantly surprised before. But the next projects after these will be restoration projects, which may be more the direction I head for the thrust of future work. Knowing though that I might get the bug to keep upping my game as a craftsman and do more with 3D parts. Who knows?

In any case, the trio of modern Diesels are getting close and should be finished sometime during the blocks of time for working on models during the holidays. I do look forward to running these, more then!

Continue to Part III of series

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