Calcs and info about scale for T gauge

marmot Aug 10, 2019

  1. marmot

    marmot TrainBoard Supporter

    I needed to figure out what scale I should use to generate some 3D prints of locomotives and passenger cars that I am adapting from larger scales. During this process, I have been forced to resolve the track gauge versus model scale versus prototype dimensions. I believe I have "rung out" one piece of misinformation related to the prototype gauge.

    I have measured and calculated a few different ways to convert larger scale models down to T gauge. I know T gauge is defined by the 3 mm gauge, not the scale. So I understand there are a few different scales utilized for T gauge. I know Eishindo (the manufacturer) says it's 1/450 scale on 3 mm gauge. The piece of info that is basically a square peg that is forced into a round hole is when anyone says the reference prototype is 3 feet 6 inches. Any way I calculate it or try to rationalize it, the 3'6" bit of info strongly disagrees with the 1/450 scale. It's WAY off - closer to 1/355 scale needed for 3'6" (1067 mm). Simply take 1067 mm divided by 3 mm = 355.

    I happen to be modeling a prototype with 3'6" gauge. That's why this clash of info matters to me. So I can't just be lazy and accept the tidbit about 3'6" gauge.

    Mark Watson's stated scale of 1/480 makes a whole lot of sense to me now for 4'8 1/2" (1435 mm). In fact, that helps to re-inforce that my various calcs are correct.

    The 1/450 scale for 3 mm gauge means the theoretical prototype was roughly 4'5". I see on a wikipedia page for Japan's railways that 3'6" is the most common, but they also have some 4'8 1/2" and a little bit of 4'6". Japanese track gauge is about halfway down this wiki page:

    I see on Eishindo's web page that they say T gauge is 1/450 scale. They never say anything about 3 ft 6 in or what the prototype track gauge was.

    I think it's very possible that they chose the 1/450 scale to go along with their existing 1/450 scale airport series. As of August, 2019, they haven't updated their web site since 2008 based on their posted schedule of upcoming exhibitions in 2008. They had existing 1/450 scale aircraft and airport accessories back then.

    My conclusion: Since the large majority of Japanese railways use 3'6" gauge, someone later inserted an incorrect assumption that the 1/450 scale is somehow related to Japan's most common 3'6" gauge. As I now see it, any reference to 3'6" gauge is misinformation relative to T gauge. I think their selection of 1/450 scale was somewhat arbitrary, so it makes the most sense to me for modelers of U.S. standard gauge to say it's 1/480. My awkward situation of trying to model 3'6" on T gauge means I should ideally try to stay closer to 1/355 scale, although this might be futile because the limited selection of motorized chassis and wheels means the size of the trucks/bogies/wheels will probably look ridiculously small relative to the rest of the cars and locomotives. Just to make it look decent, I might have to throw in the towel and just get it to look decent with whatever scale works on those chassis'.

    Please let me know if you agree or disagree or if you have any additional info. Thanks!
    gmorider likes this.
  2. martink

    martink TrainBoard Member

    I just took some rough measurements of the models of the UK HST, and their bodies are to 1:440 (+/-10). Since there isn't all that much in RTR, it is probably best to pick something as your reference and build everything to match that. 1:480 from the track gauge is one obvious choice.

    Sadly, UK modellers are used to distorted gauges and scales due to the historical dog's breakfast of HO/OO/EM/P4 and the way this infected the neighbouring scales. Aussie modellers have similar problems since we use standard HO or N to represent Victorian 5'3". Sigh.
  3. Tilbury Lines

    Tilbury Lines New Member

    One nice thing about T gauge scaling out to 1/480 is then the “T” can stand for Tenth O scale.
    Or if we want to sow confusion, the 1/450ers could keep “T” and the 1/480ers could call it TO.
  4. SVRailroader

    SVRailroader TrainBoard Member

    Adding to the confusion...I seem to recall hearing that Japanese-prototype N scale tends to be 1:150 (Someone can correct me on this), whereas most N scale is 1:160. That lines up with the 1:450 and 1:480 confusion, since it would make T scale three times smaller than N. And N scale is 9mm, so if T is 3mm that also lines up.
  5. Mr. Trainiac

    Mr. Trainiac TrainBoard Member

    You are right on the Japanese scale. The only outlier is the Shinkansen stock which runs on standard gauge. Those are still 1:160, but everything else is scaled up so the narrow gauge trains can run on the same track. That is an interesting observation on the T scale to N scale ratio, and it seems to make sense. However, even 1:150 is incorrect, which is probably what Marmot is noticing. If T scale is in fact derived from the Japanese 1:150, the error isn't just in T scale, but can be traced back to N too.

    I think as long as your models 'look right,' they should be fine. It is difficult to measure at that scale, and even more difficult to build something that small. Everything will (probably) have to be slightly oversized to be feasible.

    Regarding truck size, I think the oversized flanges are working to your advantage. The wheels may look better in larger scales to mitigate the pizzacutter look, but the wheelbase might be too short in larger scales. If you were somehow able to get a longer truck wheelbase with existing T wheelsets, you would be able to scale up to your preferred larger 1/355 scale and not have 'tiny trucks'.

    Are you planning on printing on a personal printer of through Shapeways? How do T scale trucks work? Are the wheelsets needlepoint like HO or N, or are they inside bearing? Can you swap out sideframes easily?
  6. Kurt Moose

    Kurt Moose TrainBoard Member

    Herpa makes all sorts of cars, buildings and airplanes of course, in 1:500 scale. Pretty detailed stuff.
  7. Mr. Trainiac

    Mr. Trainiac TrainBoard Member

    And if you scaled up to 1/350, that is a popular ship modeling scale too. Anything accessory or kit-wise would be perfect for your larger interpretation of T scale.
    Kurt Moose likes this.
  8. Cleveland T Scale

    Cleveland T Scale TrainBoard Member

    The route I am taking on my 3D prints and trucks are sticking a bit more to the Europe designs and not getting too worked up on all the track guages as its a lot like G scale in the 1:29 scale vs other scales in G track. I kinda found that the trains that are measuring 8mm wide and wider in T scale look a bit out of proportion unless you are going for the true narrow gauge look of prototypes.

    I stuck to a max 10ft 5inch wide limit which is right in the range of 7.2 mm wide in T scale not gauge. This seems to work well so far as the cars are proportional to a realistic version in the prototypes. Also its a matter of clearing building platforms and such in this scale. So to say I am sticking with the plate sizes from prototype scaled down and not worrying too much that the tracks are 3mm wide. I am running 1:450 on all of my printed items. Mainly as I want these compatible with other manufacturers 1:450 items they make.

    Kez likes this.

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