Simulated diesel frame members?

[cpr4200]

Did a cursory search, but didn't find anything relevant.

I'm sure someone here has modified locomotive frames to simulate the prototype's I-beam construction. Currently thinking of doing it to an Atlas RS32 and a C424. Any pointers?

[Mr. Trainiac]

I've glued a thin sheet of styrene to the bottom of a diecast chassis before. If you make it slightly wider than the chassis, it will overhang on the sides, making it look like the foot of a beam (at least from normal model viewing angles). You'd have to cut a hole for the geartrain and make sure you don't affect the ride height of the locomotive, but it works on certain models.

[Christian]

Here's one I did in about 2005. Atlas GP38 with ARR jewelry. The model is currently tucked away but I think I cemented a strip of scale 2X8 under the existing frame. Making the appearance of the frame 2 inches lower helps the look of the model. Looking at the picture I realize how many under frame detail parts have become available since I did this model. I really should go back and add electrical cables.

My feeling at the time was that it is a detail that doesn't have much impact unless your locomotive's paint is light or covered with mud and dust. Never the less I did do that frame detail from that point on. It was too easy to skip. I think that some models that have come from the factory with the simulated "I" beam have flanges that are too thick. Walthers SD50 for example.

[cpr4200]

^^^ That looks good. Much easier than I had contemplated, just adding one piece to the existing frame.

[big train james]

Aug 3, 2024 10:58:25 GMT -8 Christian said:

.......I think that some models that have come from the factory with the simulated "I" beam have flanges that are too thick. Walthers SD50 for example.......

EMD frames aren't composed of I beams, rather there is a bottom plate with structural T members welded on top. The bottom plate does extend past the web of the T, so it does end up looking like an I beam. However, the top and bottom "flanges" aren't the same thickness. The bottom plate on an sd40-2 is 3" thick, whereas the flange on the T is about 1.25" thick. I doubt the bottom plates got any thinner on later locos, and a quick look at the sd50 clearance diagram from the Utahrails website shows the same design as the sd40-2.  So the bottom plate on the sd50 should be pretty thick.

Jim

[markfj]

Aug 3, 2024 15:18:41 GMT -8 big train james said:

Aug 3, 2024 10:58:25 GMT -8 Christian said:

.......I think that some models that have come from the factory with the simulated "I" beam have flanges that are too thick. Walthers SD50 for example.......

EMD frames aren't composed of I beams, rather there is a bottom plate with structural T members welded on top. The bottom plate does extend past the web of the T, so it does end up looking like an I beam. However, the top and bottom "flanges" aren't the same thickness. The bottom plate on an sd40-2 is 3" thick, whereas the flange on the T is about 1.25" thick. I doubt the bottom plates got any thinner on later locos, and a quick look at the sd50 clearance diagram from the Utahrails website shows the same design as the sd40-2.  So the bottom plate on the sd50 should be pretty thick.

Jim

Old photos I posted before, but they say a picture is worth a thousand words!





Thanks, Mark J.
Reading PA

[cpr4200]

Would the plate thickness vary according to customer requirements? Seems like a good way to add ballast or reduce weight a bit.

[big train james]

There's a post from 2017 on the Diesel Detailer forum where a WSOR guy stated some ex-MILW sd40-2's got extra ballasting by adding plate on top of the frame but under the standard tread plate walkways. I have never heard of it being added anywhere else, but that doesn't mean it wasn't. But I suspect the frames would have all been built to the same design.

Jim

[pjm20]

Generally the changes to frame construction are due to the progression of locomotive models, ie every model will be somewhat unique in construction. Most of the time it is small changes eg traction motor blower duct location, or how the engine bay is constructed, but sometimes it can be as significant as the frame material thickness, etc. The more esoteric the model, like the GP15/20D, the more variance.

[sp3205]

I've been doing that ever since Bob Zenk's article in the December 1983 Mainline Modeler showing how he did the intricate under frame details on his model of a F40PH.  Dave Hussey did the same thing on his scratch built ATDF SD39.  I keep the frame members and associated detail as part of the deck rather than attach it to the model's frame itself, I fine it makes it much easier when it's all constructed as an intact piece.  However, most model frames are made with material underneath the deck to provide support, and that interferes with any attempt to do such detailing.  I mill the frame enough so that it will fit inside the frame supports added to the underside of the deck, as this Athearn SD45 frame shows (ignore that the rear weight is on backwards!:

This photo shows how all the details are part of the deck:

This SD40T-2 model how it all fits integrally with the modified frame:

It does enhance the model when viewed at a scale "eye level," but it's not very noticeable from how we typically look at them, and certainly isn't all that noticeable from a distance.

I should note that I've done this on a modified Scale Trains SD40-2, and no modification of the fame was needed.

Elizabeth

[TBird1958]

I've used Evergreen 'C" Channel either .080 or .100 for Atlas and Athearn units


Flat and strip stock for the fishbelly GP30