Why 1:148 scale?

[rocor]

I have been trying to discover why 1:148 scale was set as the scale for British N gauge. I understand why the 1:160 scale that the original continental manufacturers choose was not adopted in Britain, as our prototype locomotives tended to be smaller, and it was thought advantageous to increase the scale to fit the motors in, but 1:148 scale!. There was already a scale that British small scale railway modellers were using (2mm/ft) so why was that not the chosen scale for British N gauge?. It is not even a convenient size (2.06mm/ft) to model to. If whoever decided on the scale was thinking in imperial measurements, then a scale of 1:144 (1/12"/ft) would have seemed more rational. 

[009 micro modeller]

I think Treble-0 was 1:152 as well which makes it even stranger. Using a minutely larger scale also makes the track gauge slightly more under scale.

[The Johnster]

It is a repeat of the OO/HO debacle for, ostensibly, the same reasons of motor housing space.  Presumably the principle behind this is that, if 4mm scale modellers are prepared to accept the anomaly of scale and gauge implicit in 00, then 2mm modellers will be happy to put up with half the size of anomaly in N.  Henry Greenly has much to answer for, though I have enormous respect for the work he did at the time...

Edited April 18, 2018 by The Johnster

[009 micro modeller]

But half of 00 scale would be 1:152, 2mm scale, which I think was rocor's point.

[Horsetan]

But half of 00 scale would be 1:152, 2mm scale, which I think was rocor's point.

...and the track gauge would then be 9.42mm

[The Johnster]

Both fair points; I was sort of assuming he was asking why 1:160 had not been adopted as in Europe.  N is not half of HO or OO in terms of track gauge.

[2mmMark]

The N Gauge Society published a good history of the scale. 1:148 scale appears to be the brainchild of Sidney Pritchard (Peco) and  Peter Middleton (Highfield).

[rocor]

I looked at the N Gauge Society web site before posing the question on this forum, but though the scales used for British, Continental/American and Japanese N gauge are defined, there is no mention as to how the scales originated. This question may well have been covered in their journal/newsletter at some stage.

[rue_d_etropal]

Like the reasons for OO as opposed to HO, it was the size of commercially produced motors that led to British models being at the slight bigger scale. I would imagine 1/160 was adopted in Europe as they were trying to make models as small as possible. Maybe the old Trebble O models defined the overal size, so making continental models which looked bigger,as they would be in same scale,might not sit so well with those who wondered why they looked bigger. The slight increase in size might have also made the models too expensive.

Idid look at 1/152 for some of my 3D printed models, but it was surprising just how much narrower they were and coach body would not fit onto Japanese N gauge chassis, so switched to 1/148. Anyone wanting true N 2mm/ft , and I can still do it.

I think most N scale buldings, certainly British ones tend to be 2mm/ft ie 1/152, and no one notices.

[009 micro modeller]

Interestingly the original push along Treble-0 was essentially Triang 00 copied at half size. This extended to the gauge, which was 8.25mm. Lone Star switched to 9mm for the electric stock, though I think still using 1:152 for a mixture of British and US prototypes.

[RexAshton]

My understanding was that, as in 00 British loading gauge meant that the models would have been too small for the available mechanisms if we had adopted the continental scale of H0. The extra linear scale of 4mm :1' allowed the use of standard motors. The same would have been the case in the early days of what would become N Gauge where many of the kits available at the time were designed for continental chassis which because of their larger loading gauge could be fitted in at a more accurate scale. I could of course be completely wrong!

[DaveF]

Some of the early Arnold n gauge locos were larger than they should have been at 1/160 scale.  The body interior was completely full of motor.  So even a larger prototype caused problems.

 

Of course they have long since been retooled to the correct (for continental) 1/160.

 

David

[Il Grifone]

The original 000 scale was 2mm:1ft. with 9.5mm gauge  (half American 00, but whether that is relevant I don't Know) requiring very fine wheels. As everything had to be scratch built, this was not too much of a problem. For basically toy trains (Lone Star) something less critical was needed, so a bit was shaved off the gauge to 9mm. Their choice of prototypes (two British diesels, an F7 and a tender driven US 0-8-0) allowed plenty of room for the motor. Smaller prototypes needed either an even smaller gauge - a non starter as regards track (two ranges would be a no-no)  or a larger scale. The result was 1:152....

[009 micro modeller]

Did anyone actually use American 00, considering that H0 is mainly used there now? I had heard of 'semi-finescale' 4mm scale using 19mm gauge before but not much information.

[34theletterbetweenB&D]

Some of the early Arnold n gauge locos were larger than they should have been at 1/160 scale...

 For some unexplained reason this approach - which has been the common continental European compromise in both HO and N - does not appear to have been generally accepted in the UK. Practise in HO was and is flexi-scale. If the prototype was too small to allow the mechanism to fit, the target 1:87 scale gets adjusted where required. It is not far to look to find outside cylinder HO steamers which are - strange coincidence - roughly 1:76 across the mechanism. Those of a certain age will recall the HO Royal Scot from Rivarossi as an example of this method.

[rocor]

Defining a model railway by gauge does give a certain amount of flexibility as to which scale to accommodate a given prototype. Even in the larger sizes such as American gauge 1, where there is variation of between 1:29th and 1:32th scale being used. My original question was posed because of my curiosity as how a definitive scale of 1:148 was arrived at for British N gauge, by whom?, why? and when?.

[Allegheny1600]

Did anyone actually use American 00, considering that H0 is mainly used there now? I had heard of 'semi-finescale' 4mm scale using 19mm gauge before but not much information.

Yes! http://americanoo.blogspot.co.uk/2011/01/american-oo-in-1936-part-i-battle-of.html

 

 For some unexplained reason this approach - which has been the common continental European compromise in both HO and N - does not appear to have been generally accepted in the UK. Practise in HO was and is flexi-scale. If the prototype was too small to allow the mechanism to fit, the target 1:87 scale gets adjusted where required. It is not far to look to find outside cylinder HO steamers which are - strange coincidence - roughly 1:76 across the mechanism. Those of a certain age will recall the HO Royal Scot from Rivarossi as an example of this method.

"Practice in H0 was and is flexi-scale"!?!

While I agree this practice did occur, back in the sixties and seventies, prior to everyone settling down to true H0 scale at 1/87* - please illustrate your point with an example from more recent times! Your Rivarossi Royal Scot is a pretty old model but it was at least consistently (& accurately) modelled at about either 1/80 or 1/82 (I can't remember which).

Other manufacturers modelled in scales ranging from 1/80 through to 1/90 (at least they were consistent through their ranges) but eventually, everyone subsequently settled upon 1/87.

The only practice I know of where you could accuse them of working in "flexi-scale" is with coaches where the overall length could be taken at 1/87, 1/93 or 1/100 but all the remainder of the dimensions are accurate to 1/87.

This is no different to what British manufacturers have done through the decades and with locos not just coaches!

Cheers,

John.

 

* The American use HO at 1/87.1, bless 'em.

[Il Grifone]

Rivarossi scale was nominally 1:80, but some things suffered from an elastic ruler. The buffer spacing is 1:87 for instance. This tends to make things look wider than they are of course.

[009 micro modeller]

I'd rather have something slightly overscale with correct proportions than something correct in one dimension but not another.

[brightspark]

My understanding was that, as in 00 British loading gauge meant that the models would have been too small for the available mechanisms if we had adopted the continental scale of H0. The extra linear scale of 4mm :1' allowed the use of standard motors. The same would have been the case in the early days of what would become N Gauge where many of the kits available at the time were designed for continental chassis which because of their larger loading gauge could be fitted in at a more accurate scale. I could of course be completely wrong!

This is the story that is now the accepted norm and then finishes with, then EM was invented to correct the gauge and finally P4 when people wanted to go dead scale...but neither of these produce good running models.

The real truth is that there were notions of going smaller than O gauge. At the time around the 1920's O was considered as small as you could practically go. O should really be 0 as it was smaller than gauges 1,2 & 3. OO or 00 and then 000 as a naming convention make more sense if you put a decimal point in front of them and consider them as a decimal number.

By the the 1930s there were a number of different OO scales sold by different manufacturers. The proposed new standards for OO was OO course 16.5mm track, OOfine on 18mm track and a 19mm track. OO fine became EM gauge, 16.5 became what we call OO and was adopted by manufacturers after the war as you could achieve a "reasonable radius" that is a small radius curve to get the train around a table top. Thats where TT came from that became 3mm scale. The 19mm track standard never took off even though this would be closest to 18.83mm. The problem being that the corners were too great to make a circuit. (Curves are restricted by the amount of clearance required on coaches and locos especially long wheelbases). At the time the thinking was that all model layouts had to be circular in nature. This is why Peter Denny's Buckingham (and there was a prewar end to end layout) broke the mould as it was in finescale and end to end.

 

 

Back to the topic, I just want to say that what I find amazing is that the early 2mm models were coming to light in the magazines during the war years when materials were being rationed and OOO was still just a concept. So the question why the funny scale and track gauge when 2mm was already established.

[009 micro modeller]

In a similar vein some early 009 models were actually built to 4.5mm scale, making a more accurate 2ft gauge. But some of these used 9.5mm gauge.

[rocor]

In the absence of me finding any historical  information regarding the origin of the scale, my best guess would be that 1:148 was the very smallest scale that the available mechanisms would fit into for first RTR British outline locomotives. So to an extent it would have been an arbitrarily arrived at scale. There would have been a certain amount of wriggle room regarding the scale e.g. they could have scaled larger, though if for instance 1:144 scale had been chosen, there would probably now be fine scale N scale modellers building their own track-work to 10 mm gauge.

[xm607]

Its the old one in any scale, say from O gauge down, to keep costs low for a smaller British market, British body,s to the same scale would not fit onto a Continental chassis with out increasing the size, the Trix A2/A3 and Minitrix Britannia are good examples. They use a modified German pacific chassis as a starting point, unlike now where the manufacturer / tool maker stars with a clean sheet of paper so to speak, even with similar models or even between batches of the same models, OO Gauge "Bogie bolster C" plateback bogies I have found at least three slightly different ones from different production batches. It's not just down to one person or company, the idea of just making the model's a bit larger for the U.K. would be obvious to any manufacturer trying to enter what was essentially a toy market from the 1920's say, onwards.

Steve.

[Il Grifone]

The first 'model' scales (gauges really were 1 2 and 3 roughly in the proportions 1 : √2 : 2. All these need a lot of space and it was deciced to follow the sequence down with 0 (approximately half 2. Several attempts have since been made to produce models in half 1 (H1 now S) but nothing came of them and it's now a specialist scale. This left 0 as the smallest size, but something smaller was really required.

 

00 started in the twenties  with the Bing Table Railway. Intended as Half 0 (hence H0), it had 5/8" (16mm) gauge . Obviously designed for the German loading gauge, they were oversize for British prototypes. (I won't say overscale - scale had very little to do with it. Allegedly, when challenged on this point, Greenly (who was involved in the project) stated they are built to 4mm scale. Eventually H0 came to mean 3.5mm and 00 4mm both on 16.5mm gauge (the extra half millimetre was found necessary for free running).

 

The same thing happened later on with N driven, by a pre-existing 000 2mm scale.

 

http://www.brightontoymuseum.co.uk/index/Category:Bing_Table_Railway

 

"Four millimetre scale was then adopted by Trix Twin Railway and Hornby Dublo, and once its use had reached critical mass in the UK it became the country's standard. Elsewhere, manufacturers used later, more accurate "scale" wheels that allowed more proportional 3.5mm to the foot modelling, and this became known as H0 gauge, for "Half 0 gauge".

 

This is not strictly true. The first Trix Twin trains were the same as the German Trix Express (allegedly 1:90) and the "more accurate 'scale' wheels" were no more so than Dublo's, the reason they could stick with 3.5mm scale was the larger Continental loading gauge. Even so some models were 1:85. 1:82 or even 1:80. It's not so much the motors that are the problem as the wheels and motion.

 

Sorry to stray from N/000, but it's an example of history repeating itself.