Specifying Scale & Gauge

[davknigh]

Recognised yes, and I agree that they are not going to change.

 

But being widely recognised does not in any sense make them "official". Neither the NMRA nor MOROP have any legal monopoly on the naming of model railway sizes, or the standards dimensions used. You and I can get together and publish something entirely different -- and it would be just as "official".

 

There is one small point that bears mentioning. The NMRA and I suspect MOROP has the ear of the manufacturers to a far greater degree that DOGA, EMGS and the Scalefour Society have ever had. Products built for the HO market meet NMRA standards if they want to have wide acceptance and this has been the case for a long time. Bachmann and Hornby, OTOH, mount couplers at a height to suit their own stock and if it matches someone else, you're lucky. I can take my HO stock and put it on any HO layout that has been built to NMRA standards and it will run, the same can not be said, with confidence, of 00.

 

Cheers,

 

David

[hollywoodfoundry]

My point exactly. This seems to be an attempt to rename HO , HOe and HOm , not to mention On30, as well as the UK gauges without bothering to consult the vast majority of modellers working in those scales, who've already sorted out their own "settled system" with the authority of tens of thousands of modellers signed up behind it

 

Whoa there. This is not an attempt to do anything of the sort.

 

This subject is rapidly becoming a game of Chinese Whispers. Look at the heading to this Sub-Form, 'Modelling Musings and miscellany'

 

I asked at the beginning if there was a need to specify scale/gauge another way, I was not trying to force an idea on anyone, simply opening the subject for discussion. I have also said that I do not give the idea any chance of succeeding, given how the existing descriptions are so entrenched.

 

Don't forget that while you may quite easily understand what names like P4 mean, much of the rest of the world does not have a clue because the term P4, for example, does not in itself convey any information as to the scale or gauge employed.

[F-UnitMad]

This has always been a source of interesting conversations when I display my portable at shows here in Canada. Trying to explain P4 to people who are used to HO invokes much eye rolling and head scratching on their part. Which boils down to "why didn't you guys do it right in the first place?" .

:lol: That quote just about sums up the whole morass of British scales and gauges..!!

[martin_wynne]

davknigh, on 18 December 2009 - 15:11 , said:

 

This has always been a source of interesting conversations when I display my portable at shows here in Canada. Trying to explain P4 to people who are used to HO invokes much eye rolling and head scratching on their part. Which boils down to "why didn't you guys do it right in the first place?" .

:lol: That quote just about sums up the whole morass of British scales and gauges..!!

Depends what you call doing it right.

 

All H0 models are overscale width over the running gear -- because it doesn't make sense to have combined an exact-scale track gauge with overscale RTR wheel profiles.

 

This is especially a problem for UK-outline steam models with splashers, which cannot be modelled to scale width in H0. The sensible solution is to reduce the track gauge so that the dimension across the outside of the wheel faces is to scale.

 

It's the UK which got it right in the first place, with two sensible options:

 

Exact scale wheels with an exact scale track gauge (P4), or

 

Overscale wheels with a reduced track gauge (00, EM, Gauge 0, etc.)

 

 

regards,

 

Martin.

[Talltim]

This has always been a source of interesting conversations when I display my portable at shows here in Canada. Trying to explain P4 to people who are used to HO invokes much eye rolling and head scratching on their part. Which boils down to "why didn't you guys do it right in the first place?" .

P87

 

Of course, there will always be a few things that defy any sort of logic...

 

Yeah, why make a diesel look like a steam engine?

[Miss Prism]

Don't forget that while you may quite easily understand what names like P4 mean, much of the rest of the world does not have a clue because the term P4, for example, does not in itself convey any information as to the scale or gauge employed.

It does hinge on how much you want to include in or deconstruct from the meaning of 'understand'.

 

I accept the example of "P4" is probably not a good one if seeking a shorthand term immediately 'understandable' by someone who has not encountered it previously. It is however a recognised term in the model railway world, and an acquaintance with "P4" will convey information not only on scale and gauge but also on other critical rail and wheel settings and the required characteristics of the wheel tyre. That acquaintance might deepen to an appreciation of how interoperability is a key objective of P4, although whether such an appreciation is necessary for an initial 'understanding' is debatable. Scale and track gauge are two (admittedly primary) attributes, but they are not the only things necessary to 'convey' or to 'understand'.

[hollywoodfoundry]

Depends what you call doing it right.

 

All H0 models are overscale width over the running gear -- because it doesn't make sense to have combined an exact-scale track gauge with overscale RTR wheel profiles.

 

This is especially a problem for UK-outline steam models with splashers, which cannot be modelled to scale width in H0. The sensible solution is to reduce the track gauge so that the dimension across the outside of the wheel faces is to scale.

 

It's the UK which got it right in the first place, with two sensible options:

 

Exact scale wheels with an exact scale track gauge (P4), or

 

Overscale wheels with a reduced track gauge (00, EM, Gauge 0, etc.)

 

 

regards,

 

Martin.

 

Martin that is only an issue if width over the running gear is important to you. It is an equal argument to say the 'sensible solution' produces an error in the gauge. The H0 community has the equivalent of exact scale wheels to exact scale track gauge with Proto:87, just as 00 has with P4.

 

And there are new RTR products coming out of China with Code 88 wheels which are only 0.25mm wider than P4 wheels and it is quite possible to hide that extra 0.5mm in the design of a locomotive and keep the width of the running gear correct.

[martin_wynne]

Martin that is only an issue if width over the running gear is important to you.

Of course. But why shouldn't it be important? Why is track gauge always regarded as more important than anything else? Why is a scale track gauge more important than a scale width over steam locomotive splashers, scale width bogie side frames and scale platform gaps?

 

 

The H0 community has the equivalent of exact scale wheels to exact scale track gauge with Proto:87, just as 00 has with P4.

Yes, but the H0 community makes the mistake of trying to run both on the same track gauge. That is the point I was trying to make. It's not a sensible thing to do. Conventional H0 needed a reduced track gauge to enable rolling stock to be modelled to scale with RTR wheels.

 

 

And there are new RTR products coming out of China with Code 88 wheels which are only 0.25mm wider than P4 wheels and it is quite possible to hide that extra 0.5mm in the design of a locomotive and keep the width of the running gear correct.

But Code 88 wheels don't run properly on standard H0 track! They break the basic rule for all railways (prototype and model) that the wheel width must be greater than double the flangeway gap. Otherwise the wheel is not supported at crossings (frogs) and will drop between the rails. At least the original H0 designers got that bit right with Code 110 wheels (110 thou wide) for use with the 50 thou flangeway gaps.

 

regards,

 

Martin.

[Pennine MC]

Needless to say, any suffix denoting 'finescale' or other emotive quality will doom the venture from the start.

 

And if it doesnt, we can then use the same working party, with its inherent expertise, to officially define modern image

[IC126]

Don't forget that while you may quite easily understand what names like P4 mean, much of the rest of the world does not have a clue...

Does this matter, as long as the (for example) P4 modeller does?

[Peter Kazmierczak]

So if one is interested in restoring full size trains, then one would be working in 1/1435 (standard gauge) or maybe 1/1600 (Irish gauge).

 

Think I'll stick with 00 etc.

[hollywoodfoundry]

But Code 88 wheels don't run properly on standard H0 track! They break the basic rule for all railways (prototype and model) that the wheel width must be greater than double the flangeway gap. Otherwise the wheel is not supported at crossings (frogs) and will drop between the rails. At least the original H0 designers got that bit right with Code 110 wheels (110 thou wide) for use with the 50 thou flangeway gaps.

 

regards,

 

Martin.

 

Check out this model: http://eurekamodels....au/Garratt.html

 

That is running on Code 88 wheels and standard Peco track, and according to all reviews, it does it just fine.

[hollywoodfoundry]

Does this matter, as long as the (for example) P4 modeller does?

 

Taking a global perspective, yes.

 

The only truly international scale/gauge is HO, and while not often used in the UK, is common throughout the rest of the world. It would be much less confusing to have a system that does not require you to go and look up tables or specifications to find out the meaning of the term.

 

I cannot remember which, but at least one of the UK scale/gauge terms required you to be a member of their society in order to find out what the meaning of the term was.

[martin_wynne]

That is running on Code 88 wheels and standard Peco track, and according to all reviews, it does it just fine.

No it doesn't.

 

Of course, it depends what you mean by "just fine". The reviewers may be so used to the idea that wheels drop into crossings (frogs) with a bump, that they regard it as "just fine" if it doesn't actually derail.

 

But prototype wheels don't drop into crossings -- and nor do model ones if you use the correct wheel-width to match the track standard. That means a minimum of Code 110 wheels for standard H0 track, and possibly even wider for Peco 00/H0 pointwork.

 

regards,

 

Martin.

[Ravenser]

Taking a global perspective, yes.

 

The only truly international scale/gauge is HO, and while not often used in the UK, is common throughout the rest of the world. It would be much less confusing to have a system that does not require you to go and look up tables or specifications to find out the meaning of the term.

 

I cannot remember which, but at least one of the UK scale/gauge terms required you to be a member of their society in order to find out what the meaning of the term was.

 

 

However the rest of the world knows perfectly well what HO and N are, and as I understood it, whoever was floating this idea was also proposing a different nomenclature to describe HO (and presumably N) - it wasn't just a set of descriptions for British modelling.

 

I remember Iain Rice came up with a systematic and rather more familiar system in the pages of MORILL, which retained the familiar names - it didn't get adopted by others though

 

I think the basic point still stands - if you are outside Britain and interested enough in British modelling to have a go, you'll need to do afair bit of research anyway, and finding out the meaning of the various gauge names is just one, pretty easy, bit of that research

[Miss Prism]

It would be much less confusing to have a system that does not require you to go and look up tables or specifications to find out the meaning of the term.

 

In my perspective, the 'meaning' of the term is constituted by those tables and specifications.

 

Or are you saying that you would find useful a table of three columns ([term]; scale ratio; track gauge in mm)?

 

Or are you saying that you regard scale ratio and track gauge sufficient for your understanding of the term?

[Ron Solly]

Interesting to say the least.

 

Not sure about MOROP but the NMRA did at one stage represent 30000 members including many from all over the world. When the Australian Model Railway Association got started , they seeked & got approval to use NMRA standards for the Australian model scene as they saw no sense in re-inventing the wheel for 3.5mm/ft scale. And of course the American 00 is 4mm on 19mm track & has been that way for years.

 

That said, I am slightly perplexed in Martin's comment about standard H0 track, does he mean Code 100 or 83 or 75 or 70 - made by many manufacturers.

Certainly with the RP88 wheels & code 100, they drop but not on Shinohara Code 70. I have not seen them in action on Peco 83 so I cannot comment.

 

Also there seems to me to be much references to UK locos not having room for splashers, etc, so that affects steam outline- so is the modern UK diesel models affected - do they have the same problems? I am not aware of such problems with diesel models from Aust or USA or even Europe.

[Pacific231G]

 

 

The thing that should be born in mind is that scale and gauge are completely separate and should always both be mentioned in any description of the model.

 

Stephen.

Usually there's no need to in H0 if you're modelling a standard gauge prototype, which the vast majority of modellers are, simply because the vast majority of the world's railways are built to 1435mm gauge and 1:87 scale with 16.5mm gauge is dead accurate (within 0.5mm) for that. Even for P87 or proto87 the scale and gauge remain the same though obviously the wheel standards and track standards in terms of crossing and check rail clearances are more accurately to scale.

 

Both the NMRA and MOROP add additional suffixes such as H0n3 or H0m if the gauge modelled is other than standard gauge but both sets of standards are really designed to enable consistency and interchangeability between manufacturers. Individual modellers can of course do whatever they want though MOROP does recommend that anyone modelling a non standard gauge prototype to a different scale /gauge combination than their norms simply states the scale and gauge rather than trying to extend their agreed system.

The irony is that coming out of model engineering it was originally the gauge that was defined (2,1, 0, 00) with the scale following automatically from that. It was only Greenly's insistence on using a false scale of 4mm/ft for 00 gauge that led to the confusion in the British hobby.

[Ron Solly]

As an aside, it is unfortunate that UK modellers did not get an organisation going years ago to represent all scale/gauges similar to NMRA or MOROP.

It did help in USA with a model rail mag editor being heavily involved with setting up of the NMRA back in 1935 or thereabouts.

Things such as a standard height for couplers was one such important standard together with a recommendation for coupler pockets.

Even the X2f coupler, made by many manuafacturers were almost identical, that could not be said about the UK tension lock for many years.

 

OK, the above is off topic but I thought slightly related to the OP.

[martin_wynne]

That said, I am slightly perplexed in Martin's comment about standard H0 track, does he mean Code 100 or 83 or 75 or 70 - made by many manufacturers.

Certainly with the RP88 wheels & code 100, they drop but not on Shinohara Code 70. I have not seen them in action on Peco 83 so I cannot comment.

Hi Ron,

 

The size of rail is irrelevant. It is the width of the flangeway gap which matters. If the pointwork is made to the standard NMRA dimensions for H0, Code 88 wheels will drop into the crossings (frogs) with a bump.

 

It's possible to build track on which Code 88 wheels will work without bumping, by reducing the track gauge to 16.2mm and the flangeway gap to 1.0mm, as for 00-SF -- see http://00-sf.org.uk

 

However, as far as I know, no such track is available commercially, and if it was it would not meet the NMRA H0 standard.

 

regards,

 

Martin.

[Ron Solly]

Martin, you referred to H0 standard but which one? - there are 3 according to the NMRA website

Proto scales http://www.nmra.org/standards/sandrp/S-3_1ProtoTrackwork.html

Standard scales http://www.nmra.org/standards/sandrp/pdf/S-3.2%202009.07.pdf

Hi-rail scales http://www.nmra.org/standards/sandrp/pdf/S-3.3%202009.07.pdf

 

or are you just rerfering to Atlas/Peco type track ?

 

I have seen RP88 wheels going thru commercial Shinohara code 70 turnouts without dropping.

 

 

[hollywoodfoundry]

In my perspective, the 'meaning' of the term is constituted by those tables and specifications.

 

Or are you saying that you would find useful a table of three columns ([term]; scale ratio; track gauge in mm)?

 

Or are you saying that you regard scale ratio and track gauge sufficient for your understanding of the term?

 

I am suggesting that scale and gauge are at the least a good starting point for an alternate way of specify the term. Agreed, they do not specify anything to do do with fine scale choices, but for the majority of scale/gauge choices used around the world, they would be sufficient. And they would avoid the problem where the term O scale can refer to possibly three different scales.

[Ron Solly]

And they would avoid the problem where the term O scale can refer to possibly three different scales.

 

I think N scale is in the same boat. UK, USA/Europe & Japanese. http://en.wikipedia.org/wiki/N_scale

[hollywoodfoundry]

And they would avoid the problem where the term O scale can refer to possibly three different scales.

 

I think N scale is in the same boat. UK, USA/Europe & Japanese. http://en.wikipedia.org/wiki/N_scale

 

Yes Ron, that is quite true. There is a similar situation in TT scale as well.

[martin_wynne]

Martin, you referred to H0 standard but which one?

Hi Ron,

 

I mean this one (although the H0 dimensions for Hi-Rail are the same):

 

http://www.nmra.org/...2%202009.07.pdf

 

As you know, the NMRA have revised all their standards in the last few months, using a "target-based" system of tolerancing. That has produced some strange anomalies and was a backward step in my view.

 

However, that page clearly shows Code 110 wheels as the designated type for use with standard H0. The target flangeway gap is now .048" (previously the flangeway gap was .050").

 

That means that using a razor-sharp vee nose, the absolute minimum wheel-width for full support at crossings (frogs) is .096" (Code 96 wheels). Code 88 wheels are narrower than this and will drop in the frog gaps as a result.

 

If you use prototypical blunt-nose vees, these are 1/2" wide in the US, scaling to .006" wide at 1:87, so the absolute minimum wheel-width then becomes .102" (Code 102 wheels).

 

The flangeway is allowed to go .002" wider than the target, so add .004" to the above wheel-widths for full compliance. Wheels normally have a small chamfer between the tread and front face, so you should add a few thou more for that.

 

There is also a top corner radius on the rails, so to ensure full level support of the wheel tread part on the wing rails, ideally you need to add a few more thou for that.

 

So it's easy to see that Code 110 wheels are the practical minimum width which will run smoothly through standard H0 crossings (frogs).

 

For the best possible running through crossings (frogs), remove a couple of thou from the top of the vee nose in the prototype fashion so that it is fractionally below the wing rails. This allows for the coning angle on the wheel tread. This is more important in the UK where the coning angle is 1:20. For most US railroads, the coning angle is only 1:40.

 

regards,

 

Martin.