Specifying Scale & Gauge

[bertiedog]

Reference to the NMRA standards and the products of Gilbert and Lionel will reveal that S gauge in the USA has been primarily a 'tinplate/hi-rail' standard compared to the fine scale of British 'S' So much so that the US equivalent of British 'S' is known as Proto 64.

 

 

 

The scale used in the US and in the UK is generally 3.5 mm to the foot which my calculator works out to

87.0857142857143 which is commonly rounded to 1:87.1 including by the NMRA, see NMRA standard scales. The results of your dubious calculation would not cut much ice. And the other Europeans are happy with 1:87, not being interested in mm:ft and probably long forgotten how they came up with such an odd scale. MOROP stds.

Cheers

Keith

 

....Nout' to do with inches or imperial measures......B)

 

.....The reference to 1:87 was lighthearted, it is the strict division of real track mm by the model track gauge........ 1435.1mm divided by 16.5mm = 86.975757575757575757575757578

 

(4 foot 8 ¹/₂ equals 56.5 inches multiplied by 25.4(metric conversion)equals 1435.1)

 

.......And S ^scale is not S ^gauge, which is where we came in with nomenclature, all the US gauges use Toy Hi-rail versions, and then a scale version, and then a super scale version. Lionel and Gilbert never made S scale railways, they made S gauge Toy Trains.

 

The toy trade dominates the Railroad Modeller far more in the States than over here, where the mere suggestion of any connection between models and toys sends shiver of rage down some modellers spines!!!

 

Trying to describe the scale and gauge relationships is complex as we have discovered, adding in the commonly used US designations for Toy Railroads makes it even more complex. The term Hi-Rail means absolutely nothing to the average British Model Railway modeller, and finding someome of here who has used a Gilbert Train set is akin to meeting someone who has seen a Dodo.........

 

Stephen.

[bertiedog]

And for a further piece of pedantic nomenclature.....

P4 is strict 4mm to the foot? a model of the real thing at 1.76.2 ( a lot quote 1:76!).....

Try 1435.1 divide by 18.83 .........

It's



 

Happy Christmas!

[JeremyC]

This point may already have been made in this thread, but I would suggest OO Gauge, HO Scale, P4 etc. are neither scales or gauges, but a short hand name for a scale/gauge combination.

 

With regard to the story of how we in Britain arrived at the odd combination of 4mm/foot scale on 16.5mm gauge there is this article on the History of 00 on the Double 0 Gauge Association website.

 

Jeremy

[martin_wynne]

Try 1435.1 divide by 18.83

Hi Stephen,

 

P4 track gauge is not 18.83mm, it's 18.5/6th mm. I've suggested a lot of the grief about it could have been avoided by using that form of gauge designation. So that can be expressed as 113/6 mm, and then

 

1435.1 x 6 / 113 = 76.2

 

 

Martin.

[Russ (mines a pint)]

'Sort of' followed this thread at first but now I'm thinking if all the energy thats gone into it had been put into building a layout.... It'd be a very nice layout- gets coat!

[Bernard Lamb]

'Sort of' followed this thread at first but now I'm thinking if all the energy thats gone into it had been put into building a layout.... It'd be a very nice layout- gets coat!

 

 

It would look very nice but the trains would not run because of the variations in the track standards.

It's all very well in theory but a lot of people fail to mention tolerances and nobody seems to be concerned about using certificated measuring equipment to check the various parts as they are made.

I wonder if any one has made a true scale turnout with the correct variation of radii on the check rails? If they have did any one notice?

Bernard

[martin_wynne]

I said if starting today there would be no reason why HO models of British prototypes could be produced as RTR. And that is still the case. Compromise would be involved, but we're doing that already.

Hi PMP,

 

Not to the same extent. As explained, for UK-outline steam in H0 the compromises would be far greater than current 00 models. They would be little more than toys. It's unlikely that the discrepancies would be acceptable to the majority of RMweb members, for example. Such toys would require major surgery to make them fit for conversion to Proto87 as scale models. Unlike the situation in 00 RTR, where conversion to P4 scale models is possible with minimal disruption to the upper works.

 

The situation for non-steam is easier, but bogie sideframes would be over wide and need narrowing.

 

regards,

 

Martin.

[28XX]

I quite agree, Martin. In fact that is 00's 'unique selling point', although it was never planned as such. There is one known compromise applied equally to all vehicles in 00 and we now know why it's there. This is surely a better situation than not knowing (without detailed dimensional checking) how a manufacturer has dealt with the 'set-track issue' on each new model they produce.

[Andy Y]

Can we please keep this topic somewhat better tempered? Further bickering may lead to it being closed off.

[bertiedog]

On the specification issue I think that what we need is just a consensus to use at least three/four terms in each description, it's name, the scale in mm /ft (or imperial), or ratio, and the model's track gauge.

 

Say for example.....

 

HO, 3.5mm to foot, 1.87 ................................ HO/3.5mm/1:87/16.5mm

or Ogauge, ( common term),7mm to foot,1:43..... O/7mm/1:43/32mm

or OO , 4mm to the foot, 1:76.2............................OO/4mm/1:76.2/16.5mm

or TT3, 3mm to the foot, 1:100...........................TT/3mm/1:100/12mm

 

For narrow gauge just add the words narrow gauge and the same combinations

 

Narrow gauge O scale, 7mm to foot,1:43............NG O/7mm/1:43/16.5mm

 

I don't think more can be done, it would fly against the accepted terms used, but at least using the above examples I think they contain the relevant information of any modeller with a passing knowledge of model railways.

 

Stephen

 

[bertiedog]

Hi Stephen,

 

P4 track gauge is not 18.83mm, it's 18.5/6th mm. I've suggested a lot of the grief about it could have been avoided by using that form of gauge designation. So that can be expressed as 113/6 mm, and then

 

1435.1 x 6 / 113 = 76.2

 

 

Martin.

Tis' only Christmas Eve, and the shades of Studiolith past are rising here!

 

Maths are dangerous in model railways, and the black art of rounding up and especially the art of "aiming" and "targeting" tolerances has always plagued kit design, somewhat complicated to my mind by CAD.

 

I once made a set of etches in nickel to fit a boat kit, all carefully measured, and with all tolerances naturally centred with complete cross checking of the totals, all worked back to basics, every dimension was scaled correctly.

 

I took the test etch along to the Boat kit makers and they tried the etch on a laser cut deck plate, laid out in Cad, and CNC laser cut, they simply did not match, and at first check the CAD was perfect according to each dimension.....taken on its own...but add in the tolerances, rounding up/down, and an imperfect match between the CAD files and the instruction set for the laser cutter, and they ended up with the laser deck 2.5mm long over 1 metre.

 

The hand done drawing was quite correct, it was the way the CAD operated that compounded errors. It was possible to easily re jig the CAD to correct to perfection, but it woke them and me up to the issue.

 

Forgetting the .2 on 1:76 caused problems years ago with an etched kit, and my bet is a lot of CAD etches are a bit iffy if closely examined.

 

I got used to tight tolerances working making laboratory test equipment, that tested British Standard test items!!, but I still know a good model from a bad one, with the legions of variations in quality and accuracy in-between the extremes.

 

Stephen.