Model Railroading > A dumb question that's been bugging me

So I've been wondering for a while now, how did they come to the conclusion that HO scale should be 1:87? It seems to me that true "half O" scale would be 1:96. Not that it matters at all, but I'd be interested to know how the standard of 1:87 came to be, when it really isn't half of O scale at all.

-James

I believe that HO is actually 3.5mm per foot scale not 1/8"

Originally O scale was 1/45.  In the USA it was changed to 1/48 because then standard rulers could be used (1/4" to the foot).  In England, because their trains are smaller, they went to 1/43.5 in order to fit the motors then available. 

When they created HO (half O) the scale they used was English O, so 1/2 of 1/43.5 is 1/87.

Stuart

Isn't HO actaully 1:87.1 for some odd reason?

Gulliver-Stuart Wrote:
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> Originally O scale was 1/45.  In the USA it was
> changed to 1/48 because then standard rulers could
> be used (1/4" to the foot).  In England, because
> their trains are smaller, they went to 1/43.5 in
> order to fit the motors then available. 
>
> When they created HO (half O) the scale they used
> was English O, so 1/2 of 1/43.5 is 1/87.
>
> Stuart

Thank you so much! It all makes sense now.

moose Wrote:
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> Isn't HO actaully 1:87.1 for some odd reason?

I believe thet the 1:87.1 is so the track gauge of 16.5 mm is correct for 4' 8-1/2".

Stuart

It’s simple... Put an HO scale boxcar on the middle and outside rail of three-rail O scale track and watch what happens.

Mr. MRL - spoiler, it’ll roll just fine.

Correct, it's rounding by using 16.5 mm for 4 ft.-81/2 in. In almost all caculations the difference in 1/87 and 1/87.1 is very, very minimal. But I use 1/87.1 anyway because I'm anal.

For example, if If you want to see how wide a 62 in. steam loco driver is in HO and divide first by 1/87 and next by 1/87.1 for comparison, you get a difference of less than a thousands of an inch!

Victor A. Baird
http://www.erstwhilepublications.com

Gulliver-Stuart Wrote:
-------------------------------------------------------
> moose Wrote:
> --------------------------------------------------
> -----
> > Isn't HO actaully 1:87.1 for some odd reason?
>
> I believe thet the 1:87.1 is so the track gauge of
> 16.5 mm is correct for 4' 8-1/2".
>
> Stuart

In a similar vane, something has bothered me also. Why is G gauge track modeled in 1:32 scale but most (not all) manufacturers model rolling stock in 1:29 scale? Always looks like trains are running on slightly narrow gauge track.

Tom

UP3806 Wrote:
-------------------------------------------------------
> In a similar vane, something has bothered me also.
> Why is G gauge track modeled in 1:32 scale but
> most (not all) manufacturers model rolling stock
> in 1:29 scale? Always looks like trains are
> running on slightly narrow gauge track.
>
> Tom

And then people went to true narrow gauge using 1:20.3

Nathan

British O scale was 7 mm to the foot, or 1:43.5. So when HO was developed in the 1930s, they used half of 7 mm, or 3.5 mm to the foot, or 1: 87.1.
Winston Hill

James 

The exact ratio of 4 feet 8 1/2 inches = 3.5 mm is 87.0857142

87.08 is close enough for me.  

87.1 is close enough for some. 

87 is close enough for the masses. 

ʎɹɹɐ˥



Edited 2 time(s). Last edit at 08/12/19 20:40 by Larry020.

Great infimration, All, and thanks for clearing it up. Another bit of knowledge to help me win on 'Jeopardy' or maybe 'Trivial Pursuit.'

Larry020 Wrote:
-------------------------------------------------------
> James 
>
> The exact ratio of 4 feet 8 1/2 inches = 3.5 mm
> is 87.0857142
>
> 87.08 is close enough for me.  

I'd think you should round it up to 87.09 rather than truncating it. But I guess that I am just a little more exacting.

Great post! I nave learned quite a bit. Thanks for the info. Original poster, not a "dumb question" at all. It was a quest for knowledge. Always good.

SantaFeRuss

The real problem is that as I've gotten older, HO needs to be bigger.  In the back of my mind I always thought "S" would have been ideal.   I don't know how people work in N and Z.

O gauge and O scale track actually measure out to be 60".  The Main reason why Proto48 modeling exists

SantaFeRuss Wrote:
-------------------------------------------------------
> Great post! I nave learned quite a bit. Thanks for
> the info. Original poster, not a "dumb question"
> at all. It was a quest for knowledge. Always
> good.
>
> SantaFeRuss

Reason I ask is because I was thinking of doing a small layout in either 1/96 or 1/100. The idea being to preserve the general feel of HO without moving down to TT or N scale, but lose just enough size to squeeze in a little more trackage and make 18" radius curves more acceptable. And of course going down this line of thinking brought me here.

It gets even more complicated.   Keep in mind that in the 1920's 30's ane 40's when the various scales and gauges were developed, the "rivet counting" modellers hadn't been invented yet, so modelers wern't as particular.  We're stuck with that legacy.

For reasons unknown the Brits established ratios using a mixture of Metric and Engish systems of measure.  That is, for example, a ratio of 7 Millimeters to the Foot for 0 scale.

And, by the way, that's '0' as in zero, not 'O' as in the 15th letter of the alphabet.  Small reliable motors were not available then, so model trains were large, and 0 gauge was the smallest, with gauges 1, 2, 3  4, and 5 each succesively larger. 

0 gauge, with a scale of 7mm to the foot was used with track with a gauge of 32mm which was close enough to satisfy modellers of the era.  When modellers on the American side of the pond started importing parts to build their own models, some rounded 7mm to 17/64 inches, some to the less accurate but more convenient 1/4 inch.  Both camps used the same 32mm (close to 1 1/4 inch)  track gauge.  Eventally 17/64 inch died out.  Some 1/4 inch scale modellers for awhile used a gauge of 1 3/16" (which scales to 4' 9" guage) callling this "Q" gauge.

When smaller motors were developed, it seemed like a good idea to start modelling in half of 0 gauge, and the Brits took two paths.

One path rounded off the number you get when cut 7mm in half and round off, so took a scale of 4mm to the foot, with a track gauge 19mm.  This came to be called 00 (pronounced 'Oh-Oh, or 'Double Oh'). 

The other path adopted the scale of 3.5 mm to the foot with a nearly correct gauge of 16.5mm, called 'H0', for 'Half 0'.

There was also a hybrid third path quite popular in England which used a scale of 4mm with an incorrect gauge of 16.5mm.

After about 1950 this all shook itself out into the scales and gauges still common today.

The scales larger than 0 have vanished, with two exceptions: Collectors and Garden Railroads.  Gauge 1 was adopted by German Manufacturer LGB for garden railroading, using a gauge of 1 3/4" (45mm) and a scale of apx. 1/2" to the foot.  This works out to a model of a prototype that would have a gauge of 3 ft 6 in.  It's very popular on both sides of the pond.

Incidentally, 00 gauge is surprisingly popular today among some of the most serious US modellers.  It works out to 36" track gauge in 1/4" scale.  Perfect for modelling narrow gauge US prototypes.

Got that?

-John



Edited 1 time(s). Last edit at 08/13/19 15:04 by LarryDoyle.

UP3806 Wrote:
-------------------------------------------------------
> In a similar vane, something has bothered me also.
> Why is G gauge track modeled in 1:32 scale but
> most (not all) manufacturers model rolling stock
> in 1:29 scale? Always looks like trains are
> running on slightly narrow gauge track.
>
> Tom

Actually, 1:32 scale is #1 gauge.  G gauge referes to any train gunning on #1 gauge track that is bigger in scale than 1:32 scale.  This is the result of LGB using #1 gauge track for its 1:22.5 scale narrow gauge trains.  When they started making American prototypes, such as F7's, they made them oversize compared to #1 scale so they wouldn't look too small compared to their European narrow gauge models.  Then other companies started making American trains to use the same track, but not the exact same scale as LGB, such as USA Trains 1:29 scale.  This way they were closer in size to the LGB models, but also close to true #1 scale.

And as another poster commented there is also F scale 1:20.3 for American 3 foot gauge trains also running on #1 gauge track.  LGB's original models were meter gauge prototypes, so 1:22.5 was very close.

Stuart



Edited 1 time(s). Last edit at 08/15/19 19:55 by Gulliver-Stuart.