I know I should know this - but I can't seem to find it.......

What is the scall between HO and full size trains?

This should just be so easy to find, but googling various HO terms just seems to showup other portals or some website trying to sell something. Along those lines, anyone know of a good model train 'reference' site as well?

Here in Europe we have morop.org wich represent most of the european railroaders. The allso have their NEM norms who descibes mutch about allmost anything.

In Europe; 1:87. In Britain; 3.5mm to 1'. In the USa; 1:87.1 (a rounding of 3.5mm:1')

While the differences are minimal, they are differences and model railway fans can be picky about such things.

MOROP (Europe) historically classifes everything from 1:80 to 1:90 as HO, probably because Trix Express (1935-60s) was 1:90 while Fleischmann was 1:82 until 1964, 1:84 1964-75) Rivarossi Italian was 1:80.

At least anal ones like you. You're going to tell us with a straight face that you, or anyone else on Earth for that matter, can tell the difference between 1:87 and 1:87.1? *Snort*.

That IS very interesting. I have heard all three scaling options but never related to a global location. The actual scale is 3.5mm = 1'. That works out to a ratio of 1:87.085714..... The difference in 1:87 and 1:87.1 is insignificant, especially if you are consistent. I always use metric for my measurements since that is what the scale is and I never have to worry how the numbers are rounded off. However, when your measuremnts get down to a tenth of a millimeter or less it's pretty hard to get absolute accuracy no matter what your measuring system is.

The actual scale is whichever of the three you decide to go with. A scale expressed in two different measuring systems is plain daft!

Sure it's insignificant, but why introduce a fudge factor (the rounding up) before introducing one's own fudge factor of working to the nearest

0.2-0.5mm or whatever? That becomes a multipication of fudge factors. (a fudge factor multiplied by a fudge factor = a blunder factor :-)

I've recently been scratchbuilding prototypes built in feet, inches and fractions thereof. My materials have thicknesses in millimeters or fractions of inches or thousandths of inches. When some component requires a combination of all three added together (as has happened) the maths required leaves plenty of room for error.

I was wondering if I could tell the difference between 1/87 and 1/87.1. I cant to my eye, however... I put this in a spreadsheet, double check my calcualtions. scale physical size in inches scale difference feet inches @ 1/87 @ 1/87.1 @ 1/87 @ 1/87.1

btw the spreadsheet calculated to more decimals, ie...

482.204362801377727

so at 200' we're talking a little more than 1/3" actual size difference between scales. Perhaps an issue if you're scratchbuilding prototype size buildings. However! A 48' container would have a 1/10" difference in size between the two scales. Considering there may be 4-8" of spare room between the container and the car sides, that 1/10" works out to 9", enough to make a

1/87 car too small to carry a 1/87.1 container. Interesting. Perhaps this is why A-Line containers don't always fit in Walthers container cars? a 1/87.1 container in a 1/87 car????

Anyone who has done the math has to realize that debating this scale subject has to be "tongue in cheek". The largest difference in the scale options discussed is .115%. That factors out to a little more that a hundredth of an inch in a foot. Divide that by 87 or what ever and you see how small the differences really are. I don't know if there is affordable instrumentation that can routinely measure that accurately, but if there is it would be a good trick to model to it.

However, converting dimensions (during scratchbuilding) dividing by 87 is quicker by two key presses than 87.1 . Generally there are a lot of dimensions to be converted so the chances of incorrect conversions is reduced. I stand by my comment that any scaling factor that uses two different measuring systems is daft.

Okay, you made an error here - that 'feet' all the way on the right should be 'inches'. A 100-scale foot high pile of 1:87.1 haggis would be .016 actual inches, or 1.379 1:87.1 scale inches, taller than a 1:87 scale model of the same haggis- heap.

.016" is about the thickness of five sheets of typing paper. This is a considerable error if you are trying for a press or snug fit on a small part (as in scratchbuilding rolling stock) but we don't usually run into single components that long. On bridges & so forth the worst you would get is a bit of a rail gap, if you were completely going by measurement.

In cutting frame slots on a steam loco, let's say 5/8" actual inches from center to center, the error between 1:87 scaling and 1:87.1 would be around .001" (actual inches).

Well, you can split a thousandth pretty easily on a micrometer, if you've used one enough times to be consistent with the pressure (there are a few thousandths of deflection between the proper 'light drag' and 'screwed down like a C clamp'.) Some have vernier lines for measuring to .0001", too. I'm certainly not at this stage in modelmaking -- my micrometer use is at work -- but micrometers are not prohibitively costly. Once you get to dimensions of around 100 scale feet and more, the difference is in hundredths, which are not impossible to read on a scale, but then the big parts like that don't usually need to be the precise ones in model railroading.

Cordially yours: Gerard P. President, a box of track and some plans.

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