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Why 32 and not 33mm?


Robert Stokes
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As I understand it, when HO gauge first started it was called that because it was short for half O gauge. Jf that is correct, it implies that at the tome, O gauge was 33mm which would have been almost perfectly correct for standard gauge to scale. Therefore when and why was it changed to 32mm?

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17 minutes ago, Robert Stokes said:

As I understand it, when HO gauge first started it was called that because it was short for half O gauge. Jf that is correct, it implies that at the tome, O gauge was 33mm which would have been almost perfectly correct for standard gauge to scale. Therefore when and why was it changed to 32mm?

 

History tends to be one stupid thing after another, but I think you are ignoring the halving of the scale.

 

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I rather suspect it was 1.25 inch gauge which would give 31.75mm duly simplified to 32mm

 

S7 does use 33mm gauge, provides for accurate frame spacing on locos, and scale flange and flange way dimensions.  These factors do have a sinificant effect on appearance.

 

to add to the entertainment 0MF uses 31.5 mm gauge with reduced flangeways, which from two coach-lengths away gives track that is indistinguishable from S7, but with the huge advantage that all RTR and existing 0F stock will run on it without modification.  But you don’t get the scale frame width and finer flanges.

 

Blame Henry Greenly and the nascent toy train industry (and ancient electric motors)!

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Does anyone know what Märklin's original gauge was? I think gauges 1, 2 and 3 were still defined in terms of inches in the late 1800s, even in Germany, so I suppose it is entirely possible that Märklin used 1¼", which is 31.75 mm. Quite when Märklin settled on 1:43.5 scale (7 mm/ft) I am not sure, but I suspect they weren't so concerned with scale back in 1900, or whenever 0 gauge was first produced.

 

However, 7 mm/ft was firmly established long before 1935 when Märklin introduced HO, and by then they were wholly metricated, so gauges were in mm. Since it was a new scale and gauge, they could do what they wanted, and 16.5 mm gauge is a very good match for standard gauge in 3.5 mm/ft scale.

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32mm gauge for 7FS scales to something like 4' 7" (rounded up) which is pretty close.  I plan to have a flutter with 0-MF on the next turnouts I build.  I've looked around but 0-MF gauges don't seem too common so I'll have a go at making some from plastic card.

 

I will report on progress in my layout thread, link below.

 

The 32mmm turnouts I have built previously work well but there is a tendency for wheels to drop into the hole at the vee.  This can be compensated by adding 0.5mm layers of plastic card.

 

John

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38 minutes ago, Jeremy C said:

Does anyone know what Märklin's original gauge was? I think gauges 1, 2 and 3 were still defined in terms of inches in the late 1800s, even in Germany, so I suppose it is entirely possible that Märklin used 1¼", which is 31.75 mm. Quite when Märklin settled on 1:43.5 scale (7 mm/ft) I am not sure, but I suspect they weren't so concerned with scale back in 1900, or whenever 0 gauge was first produced.

 

Märklin defined 0 Gauge as 35mm between rail centers in about 1893. The rails were tinplate with rail head 3mm in diameter, which gave a distance of 32mm between rails. Märklin had nothing to do with the 7mm to the foot nonsense, that was the fault of Henry Greenly and Bassett Lowke.

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Maerklin originally set the standards using measurements between the centres of tinplate rails, so when 0 was added to the initial set, it was 35mm between rail centres.

 

Now, the standard diameter of tube into which tin railheads were formed was 3mm, so the gauge as we now measure it was 32mm.

 

There was no scale at this stage, just a gauge, and trains that looked very roughly in proportion with that gauge, if you squinted a bit, and they were toys, not models.

 

Once Railway modellers got involved, via the agency of Mr Bassett-Lowke, it took a while to decide what scale to use. 1:48, 1:45, and 7mm/ft (1:43 and some tiny bits) were all tried in the early years, but in 1910 Henry Greenly ‘nailed’ 7mm/ft for British use, and laid-out a set of track and wheel standards for the first time. If you ferret through my main thread, I’ve reproduced the first table of dimensions, and several subsequent ones up to the 1930s.
 

The genius of Greenly’s initial standard was that it allowed wheels designed for tinplate track to run on ‘scale’ permanent way, made with solid-drawn rail and wooden sleepers. It was expressed in both millimetres and fractions of inches, but (this will cause confusion!) the imperial dimensions are not identical to the metric, they are very close equivalents using 1/64” as the smallest unit, and they are not toleranced. You could measure it all with a steel rule, and it all worked whichever units you used, but if you went at it with vernier callipers, you would find differences that would today cause deep consternation. The gauge was 32mm or 1.25”, which are c0.25mm different. But the trains ran on either, and both mixed together, and track that was bent inwards or outwards by a couple of millimetres, very happily!

 

People who decry Greenly’s work are missing the point completely, by failing to recognise the realities of the time: most of the trains that would run on the track were r-t-r tinplate, with cast lead or pressed tin wheels. The manufacturing tolerances were set by a combination of the skill of the tool-makers (phenomenal), the wear-and-tear on tools (pretty great), and the shrinkage proportions of lead as it cooled (not entirely controllable).

 

He provided in a parallel a suggested set of much finer standards for use by amateurs who were turning their own wheels and making their own track, but the basic standards were perfect for the vast majority of boys and men, in the same way that commercial 00 standards work for the vast majority of layout-builders now, and only a few people feel the urge to resort of P4.

 

As to scale: if you don’t like 7mm/ft, what easily measurable scale would you have used? Personally, I sort of wish he’d plumped for 1:48, which he did use for a bit himself, and which the US adopted, but a bit of extra space was always useful, both for model valve gear and clockwork springs, and it was challenging enough to build live-steam or electric in that scale, let alone the smaller one.

 

PS: Don’t ask why Maerklin used 35mm, 48mm etc, because nobody is really certain. My own belief is that those numbers resulted from standard frame sizes of cheap ‘clockworks’, which were mass-produced for use in all sorts of toys and cheap gadgets, and that adding wheels outside those frames yielded some rather arbitrary numbers. Other theories revolve around the ‘zoll’, the traditional German inch, which itself varied by location anyway!

 

 

 

 

Edited by Nearholmer
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2 hours ago, Jeremy C said:

Quite when Märklin settled on 1:43.5 scale (7 mm/ft) I am not sure


I don’t think they ever did. When precise scale eventually crept into German models, it was 1:45, not 7mm/ft. Maerklin’s models for the British market in the 1910s were all over the place in terms of proportions, let alone scale, and even as late as the 1930s they couldn’t get proportions right for British models.

 

The ones who got proportions and, so far as the technology permitted, scale, right were Bing and Carette, because Bassett-Lowke, and then Greenly, badgered them into it.

 

LNWR

 

5A0F8EC1-89C5-4BB2-88DF-63CA575C8185.jpeg.4477803fba62a2b7c87b6da4bd7662b0.jpeg
 

Maerklin

 

310EAEC5-D307-4B59-B21B-C32F4A372AE5.jpeg.d3a872d4bf508fd369688ee2ea2762a7.jpeg


Bing

 

BDEB161F-6231-44FB-ADC2-3BDD6774C8A7.jpeg.7563bf0d898984f7d85f75791a10dfed.jpeg

 

 

Edited by Nearholmer
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1 hour ago, Nearholmer said:

As to scale: if you don’t like 7mm/ft, what easily measurable scale would you have used? Personally, I sort of wish he’d plumped for 1:48, which he did use for a bit himself, and which the US adopted, but a bit of extra space was always useful, both for model valve gear and clockwork springs, and it was challenging enough to build live-steam or electric in that scale, let alone the smaller one.

 

I was not intending to decry Henry Greenly's work, for his time he did exceptional work. But his legacy is that some pragmatic decisions have become fossilised and set in stone. Looked at objectively, 7mm : 1 foot is in no way a good scale. For many reasons, but mainly because it is just plain wrong. When the BRMSB set the standard for fine scale they should have ditched 7mm / ft and gone for a truly accurate gauge of 35mm and a scale of 1:41. It would have been accepted at the time, but they were more interested in codifying the current best commercial practice.

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9 minutes ago, goldfish said:

But his legacy is that some pragmatic decisions have become fossilised and set in stone.


True. A bit like whoever settled on the structure/loading gauge that has become typical of British Railways (Stephenson?).

 

The penalty of the being the pioneers? First country to build real railways; first country to adopt railway modelling as a widespread hobby.

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6 hours ago, Robert Stokes said:

As I understand it, when HO gauge first started it was called that because it was short for half O gauge. Jf that is correct, it implies that at the tome, O gauge was 33mm which would have been almost perfectly correct for standard gauge to scale. Therefore when and why was it changed to 32mm?

As you can see in the attached catalogue page the French (Jouet de Paris) were the only ones (again) that knows how to do things correctly; they made 33 mm gauge trains.

P1070848.JPG.a2cbda156631fc8cf444243d856a2ebb.JPG

Regards

Fred

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As I understand it, when HO gauge first started it was called that because it was short for half O gauge. Jf that is correct, it implies that at the tome, O gauge was 33mm which would have been almost perfectly correct for standard gauge to scale. Therefore when and why was it changed to 32mm?

When the first Bing sets that would eventually spawn H0 and 00 were introduced I think they used 5/8" which was, of course half of  5/4".

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Something to remember about any toy railway made from tinplate is that it started out with a precise track gauge (the tooling and production processes were precise), but that after assembly, and especially after a few sessions of play, particularly after being connected, disconnected, and put in and out of a box a few times, it got knocked out of gauge all over the place. That’s why wheel-sets to run on tin track are typically very wide across the tread, and that’s why Hornby winding-keys came with a check-gauge formed into the handle; it was expected that rails would need to be de-kinked periodically.

 

All of which means that the difference between 5/8”, 16mm, and 16.5mm was, at the time, pretty much academic. I would wager that a gauge check on even a very lightly used Bing Tabletop railway would find all three dimensions (and probably others at the turnouts), especially where the joining-pins were fitted into the rail ends.

 

The classic Hornby Dublo track*, and the Maerklin track by which it was heavily inspired were incredibly robust (although even they could get bent out of gauge), but they were developed in the light of experience.

 

* Was the early Dublo clockwork track a simple tin pressing, or did that have solid-drawn rail?

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Nowadays, we take it for granted that Europe is Metric. But it wasn't always so, the Metric system was a French invention of the Napoleonic era and didn't really take hold in the Germanic nations / principalities till it was made mandatory on the formation of the Nation State of "Germany" - 1st January 1872. before that the Germanic units were similar to the British "Imperial" system that lasted another 100 years (approx) till the formal adoption of the Metric system throughout Europe.

 

When LU first ordered prototype equipment from the Swiss Brown Boveri Company in circa 1980 we were asked which measurement system and thread forms they should use - they were quite surprised when we replied "Metric of course". As a supplier to many countries they were prepared to work in the customer's preferred units.

 

So I suspect that circa 1900 Maerklin / Bing / Carette / etal. would have had a similar approach.

 

It is also worth remembering that the Germans / Swedes / other Europeans still use the "Fuss" (Foot) as a measure for timber or boats etc - albeit it is now the metric (300mm) foot!

 

Sorry if this is just muddying the waters.

 

Regards

Chris H

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15 hours ago, APOLLO said:

American O scale is 1:48, often referred to as 1/4" (!/4" = 1 ft). easy to work with, track gauge is same as UK O scale - convenient.

 

Brit15

Ignoring historic practicalities like motor size, it is a pity that we didn't adopt this slightly smaller scale. The extra coach or pair of wagons would have made a real difference to limited space modelling. I am generally a fan of the metric system but there is something about scratch building in 1/48 that seems " right" . The new scale "6" would end up on a gauge of around 29 mm.

The real issue is does a convenient gauge dictate the scale or vice versa?

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22 minutes ago, doilum said:

The real issue is does a convenient gauge dictate the scale or vice versa?

 

Historically, the gauges came first, and the scales after, certainly down as far as 00/H0, and I think also for N, which is probably why there are multiple scales associated with each of 45mm, 32mm, 16.5mm, and 9mm gauges. 45mm is particularly interesting, because it has had two different starts as a "German toy gauge", with Maerklin in the 1890s and LGB in the 1960s, with radically different intents about what the toys represented, standard and metre gauge.

 

S is a bit different, not being part of the "main set", and having been almost exclusively (not totally) a "modellers' scale and gauge" in Britain, although it does have a history as a "toy gauge/scale", and I think the application of multiple different scales or gauges elsewhere - Fred's e-book goes into detail.

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This has turned into an interesting discussion, well informed by Nearholmer's posts.

 

As a professional Engineer, I do of course recognise that there were constraints in materials & technology, whether steam, clockwork or electric, space within the model loco is clearly at a premium, and it is also clear that the determined attentions of siblings, pets, and the occasional misplaced parent's foot would all take their toll on the accuracy of the track, particularly for those "carpet layouts".  I did not know that the Hornby key included track gauges, very innovative!

 

Where I do take issue (and I do wish I could find the specific piece of text) was that Greenly, for all his evident technical  expertise, apparently allowed "art" to get in the way.  I distinctly recall reading that he felt that locos looked better on narrower-than-scale track, and of course, this is precisely what he did with the RHDR - approximately 1/3 scale stock on 15" gauge, 1/4 scale track.  There is another reason that may have some impact, the gauge very much determines the minimum radius, but I have no idea whether the RHDR gauge was determined by the land required for the Dungeness loop. 

 

And it does seem that the same sort of approach applied to 00 with a somewhat knock-kneed appearance of big-wheel locos in particular.

 

As argued by Richard Dawkins, and noted by Nearholmer, evolution never goes back down the hill and up another one - I'm sure if we were starting now, we would have metric scales in the 1,2,5,10, 20, 50, 100 etc.. format, but then again, mainline track gauge would probably be 1 or 1.5m, not 1.435...

 

Meanwhile, if you can model in S7, you'll probably have better looking locos, and definitely better looking wheels, and if not, go with 0MF.  Turned gauges were available from Debs, and I believe Roxey made etched ones.  It may be that turned gauges will be available again, you could try Premier Components.

 

atb

Simon

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23 minutes ago, Simond said:

I distinctly recall reading that he felt that locos looked better on narrower-than-scale track,


It gets worse: he wrote a long thought-piece in a very early magazine about the possibility of changing the proportions of models so that they looked “more right” when viewed from the typically high angle. He went on about using boiler fittings, and even boilers, that were deliberately out of scale proportion. When I first read it, I sat there with furrowed brow, scratching my head in mystification, because it made no sense at all to me.

 

My guess is that it came from learning about classical statuary, where scale increases from pedestal upwards, to avoid it appearing, from a low viewing angle, as if great and famous warriors had absolutely enormous feet, and were hung like donkeys.

 

I suppose we all have our funny little ideas, but few of us have opportunity to inflict them upon our peers in the way that he did.

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