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

Sunday, April 10, 2016

Progress report: a pair of American OO 3D printed SW7’s

Back in January we featured a report on the 3D printed 1:76 models available at Shapeways. I now own two of the SW7 models and have them running! All that needs to be added are paint and decals.

As designed there were several parts left off the bodies, specifically the headlights, bell, and horn. I salvaged those parts from the shells of the AHM SW1 models that donated their frame, drive, and weights to the project. The Shapeways bodies only needed slight modification to accommodate coupler boxes mounted on the frame, done on the cab end of each model only and not normally visible at all in operation.

Turning to the drives seen in the second photo, the AHM models have trucks that are the correct wheelbase for OO with nice side frames. I extended the frames of both and enlarged the fuel tanks with spare parts saved from other conversions. I then added weight to the extent that I could (the wheels still slip, they are not overweight in relation to the motor), and will paint the weights that are visible in the cab black.

Speaking of paint, be sure to check the earlier article for a discussion of this topic. As to a paint scheme, my plan now is to revive a freelance short line that I modeled in HO way back in high school. More on that in a future update, but it will make for some good operation and also is suited to the SD24 body model which I will be working on soon.

The AHM drives seen in the photos actually run surprisingly well. I knew that if I ran these drives as a pair of engines they would work better, as each model individually has only four wheel pickup and four drive wheels, both of them going smooths out operation. The pair will pull about six free rolling cars and low speed operation really is OK. These will be run.

Also very notable is that with the original AHM frame cut down as seen it nests right up inside the 3D body and the engine is exactly the right height! It took me a while to get used to the look as they are visually a good bit bigger than most of the HO conversion Diesel switchers I have been using for years.

The downside on these two models is that they make clear that almost my entire Diesel switcher fleet (!) really is not up to snuff. Almost all look noticeably under scale except for one: the Fleischmann Baldwin switcher (seen here). On it, the cab looks short but the model itself is otherwise convincing next to the full scale Shapeways bodies. So likely this summer I will rebuild another of these using parts scrapped from my SW1 conversion, and looking ahead I think the AHM S-1 models could be used to make a convincing RS-1, maybe in a few years….

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