Author Topic: Broad Gauge Dilemma  (Read 486 times)

0 Members and 1 Guest are viewing this topic.

Offline 753

  • G3 Society Member
  • ***
  • Posts: 238
Broad Gauge Dilemma
« on: Dec 17 2021 11:32 »



As a dyed I the wool GWR enthusiast I have admired Gooch’s 8ft singles for all long time and would like to build a model of one.
But there is a dilemma where as I like G3 because of its size and good mixture of model engineering and model making, if I build a broad-gauge engine to G3 standards the track gauge would be 3.85in so it would have to be a static model.
On the other hand, if I build it to fit G3 2.5in track the engine would be just under G1 size, all though I could have it running on G3 metals it would not have the impact of a G3 model therein lies the dilemma.
I think the answer lies in a glass of wine and stirring into the fire over Christmas?
Mike

Offline AshleyW

  • G3 Society News Officer
  • *****
  • Posts: 541
Re: Broad Gauge Dilemma
« Reply #1 on: Dec 17 2021 11:39 »
well for me, the social g3 gatherings are one of the best aspects and i often visit tracks without even taking anything to run. i think all members would forgive you building it in gauge 1 scale, but be far more delighted to see it run on g3 tracks. you could build it g3 and cheat a bit and make it 3.5" gauge, but then non of us are likley to see it at M.E tracks, so i feel the g1 running on g3 would be great and a super talking point at gtg's.
as an aside, i have photo's of some loco's made by a member, who sadly when first joining g3 could not get a response on the true scale, so opted for 16mm scale, resulting in his models being 3 inch gauge. i'm still going to include them in the newsletter, as it is valid. as is the next article in march featuring use of some stock not intended for g3 !!!

Offline IanT

  • Workshop Practice Adviser
  • *****
  • Posts: 1500
Re: Broad Gauge Dilemma
« Reply #2 on: Dec 17 2021 12:29 »
I'm not exactly sure what is meant by "True Scale" Ash?

Any model railway scale can be very simply worked out by dividing the full sized prototype gauge by that of the model track gauge. So British Standard gauge (56.5") modelled on 2.5" track gives an exact scale of 1:22.6.

Assuming Mike wants to model GWR Broad Gauge (at 7ft 1/4") then the scale for 2.5" track would be 1:33.7.
Likewise, if I wanted to model 3ft 6" SA locos on 2.5" track then the correct scale would be 1:16.8.

Gauge '3' is defined as being standard gauge railways running on 2.5" track, so a Broad Gauge engine is (by definition) not "Gauge 3" - but that certainly does not mean that a GWR broad gauge engine built to a scale of 1:33.7 (and running on 2.5" track) would not be welcome at G3 GTGs. In fact I'm sure quite the opposite would be true.

I guess Mike has to decide whether to model his broad gauge models to match his existing GWR models in scale and then have either a static display or run them on a custom track (which I calculate to be 3.73" gauge btw). However, by reducing the scale, these engine(s) could then be run at GTGs and would by very welcome. 

Regards,

IanT
Nothing's ever Easy - At least the first time around.

Offline cabbage

  • G3 Society Member
  • ***
  • Posts: 1556
Re: Broad Gauge Dilemma
« Reply #3 on: Dec 17 2021 13:26 »
Writing as someone who is often classed as "l'enfant terrible" I would welcome the loco to my tracks. I have an OO gauge "Lord of the Isles" in 4mm scale. But I still love it!!!

Regards

Ralph

Offline John Branch

  • G3 Society Member
  • ***
  • Posts: 112
Re: Broad Gauge Dilemma
« Reply #4 on: Dec 17 2021 14:40 »
Having got my calculator out, am I right in concluding that a model built to 9mm/ft and running on 2 1/2 inch gauge track will give a convincing model without recourse to huge numbers of decimal places, or lots of rounding up and down?
I think it would look terrific, especially with a few of the early GW coaches behind it.
John

Offline Doddy

  • G3 Society Member
  • ***
  • Posts: 359
Re: Broad Gauge Dilemma
« Reply #5 on: Dec 17 2021 15:04 »
Having got my calculator out, am I right in concluding that a model built to 9mm/ft and running on 2 1/2 inch gauge track will give a convincing model without recourse to huge numbers of decimal places, or lots of rounding up and down?
I think it would look terrific, especially with a few of the early GW coaches behind it.
John

I made the same decision with the Class 87 and MKIIs, although in my case it was 14mm/foot for all dimensions except the track gauge of 2 1/2" requiring a marginally narrower axle length.

Even worse was my investigation and research into Hitlers 3 metre gauge Breitspurbahn, that would have required an equivalent model running on 5" gauge track compared to standard gauge 2 1/2".

https://www.youtube.com/watch?v=cbPlcn9yg3A
"You don't know what you don't know"

Offline IanT

  • Workshop Practice Adviser
  • *****
  • Posts: 1500
Re: Broad Gauge Dilemma
« Reply #6 on: Dec 17 2021 15:45 »
Not far out John - 1ft would be 9.04451mm if scaled at 33.7.  :-)

With regard to a 'scaling' factor - it's partly down to how you wish to 'express' it and partly how you normally use or calculate it. For instance, I used to work out the scale of a G3 part using 13.5mm/ft (when it should actually be 13.4867mm/ft!) and that was more than near enough. But then I started using CAD and often drew at full size (because it was easier to guess that 5.75" - as measured on the drawing -  was probably actually 6") and then scaled the entire drawing down to (model) size on paper. To do this, 22.6 was the correct scaling factor for G3 and then it becomes quite natural to use this 'ratio' outside of CAD too.

You can of course still use the other conversion factors instead.
For something 64.5ft long, you can:

a) multiply by 13.5 (= 870.75mm) or
b) multiply by 17 and divide by 32 (= 34.26" / 870.2mm) or
c) divide by 22.6 (= 2.854' / 34.25" / 869.89mm).

Note that a) is the simpler if you want to go straight from feet to scale mm. All of our 'norms' produce pretty much the same end result (within 1mm on a BR coach) - so it's just a matter of preference really. One of the really good things about Gauge 3 is that there are no alternatie 'scales' to worry about!

Regards,

IanT
Nothing's ever Easy - At least the first time around.

Offline MikeWilliams

  • G3 Forum Moderator
  • *****
  • Posts: 1945
Re: Broad Gauge Dilemma
« Reply #7 on: Dec 17 2021 16:15 »
At least two members are already modelling Gauge 3 (1:22.6) broad gauge.  I am sure one of the will find this post and comment shortly.

Mike

Offline MikeWilliams

  • G3 Forum Moderator
  • *****
  • Posts: 1945
Re: Broad Gauge Dilemma
« Reply #8 on: Dec 17 2021 21:55 »
Regarding scale ratios, I prefer to work from original imperial drawings or, when there is no alternative, measure the drawing prints which are usually 1in/1ft or 1.5in/1ft.  Put the ratio into the calculator's memory and multiply each dimension.  Doesn't matter whether it has six decimal places or no decimal places - still just one button to press.

I'd keep the scale correct so it looks right with your other stock, and make track (lay one more rail) to suit.  That's what thy did in full size.

Mike

Offline AshleyW

  • G3 Society News Officer
  • *****
  • Posts: 541
Re: Broad Gauge Dilemma
« Reply #9 on: Dec 17 2021 23:48 »
the comment about true scale was, that a member wrote to g3 commitee asking what the scale we used was, and at that time never got a response. as he was familiar with 16mm n.g live steam, thought that it may be close and built his std gauge models to 16mm to the foot, resulting in a 3 inch gauge model.


Offline Doddy

  • G3 Society Member
  • ***
  • Posts: 359
Re: Broad Gauge Dilemma
« Reply #10 on: Dec 18 2021 09:12 »
One of the really good things about Gauge 3 is that there are no alternative 'scales' to worry about!
Oh dear! We're back to this issue again.  :-X
The Societies position on this is noted.
"You don't know what you don't know"

Offline MikeWilliams

  • G3 Forum Moderator
  • *****
  • Posts: 1945
Re: Broad Gauge Dilemma
« Reply #11 on: Dec 18 2021 10:31 »
One could equally say that in Gauge 3 there are no alternative GAUGES to worry about.  But both statements are completely correct for standard gauge, which is the definition of Gauge 3.

Doesn't mean we don't welcome people who push the boundaries!

Mike

Offline cabbage

  • G3 Society Member
  • ***
  • Posts: 1556
Re: Broad Gauge Dilemma
« Reply #12 on: Dec 18 2021 12:51 »
Speaking as an immigrant from a poor third world country using Cape Gauge... The CPR may be described as a horrible mish mash of "standards". The rail to rail spacing is Berne, the OHL height is US/Can 11kV (25Hz AC) and the loading gauge is - Russian... But - the gauge is std!!! Commercial buildings are 1:32, 1:29, 1:22.5 depending on which manufacturer you choose.

These are all standards -for the CPR(!)

Regards

Ralph

Offline 753

  • G3 Society Member
  • ***
  • Posts: 238
Re: Broad Gauge Dilemma
« Reply #13 on: Jan 04 2022 14:07 »
The idea of building a G1 model to run on G3 track contradicts the whole G3 ethos, and to my mind would not do justice to these wonderful engines. The reson I like G3 is the size of the engines and stock, so I will build a G3 Broad Gauge Rover class engine, and run it on a demonstration length of scale Baulk Road.
I now have drawings for the engine to suit G3, and look forward to a new build.

Mike






Offline MikeWilliams

  • G3 Forum Moderator
  • *****
  • Posts: 1945
Re: Broad Gauge Dilemma
« Reply #14 on: Jan 04 2022 19:06 »
Bravo Mike!

Alan Hutchins and Geoff Nicholls are both modelling GWR Broad Gauge in G3 so might be able to offer a short cut to track standards and exact gauge.

Mike