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Scale gauges

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IanT22/08/2019 21:42:38
1548 forum posts
144 photos

Hi Merlin,

I'm not sure anyone has given you the fully correct way to think about "scale" - but I've only very quickly scanned the thread replies. But here's my version of it...

"Scale" is very simple and relates to the relationship between the original prototype's 'gauge' and the gauge you intend to use for your model. The model track gauge can of course can be anything you want it to be - although most folk use one of the various track 'standards' mentioned. However, assuming you are modelling an actual prototype - then it would have had a fixed gauge - be that standard, broad, metre or one of the many varied narrow gauges...

I model standard gauge prototypes (4ft 8.5" ) on 2.5" gauge tracks - so the scale ratio is 1:22.6 - that's 56.5" divided by 2.5". However, if I was modelling a 2ft (24" ) narrow gauge engine on 2.5" track (as some N2.5GA members do) - the scale ratio would then be 24" divided by 2.5" - or 1:9.6.

So the 'gauge' is the distance as measured between the inside edges of the rails and the 'scale' is the ratio between the full size gauge of the engine or stock you are modelling and the model track gauge you intend to use.

However, for ease many of the standard "gauges' use approximations of the scale...e.g. 1" scale for 5" tracks... These are really just convenient rules of thumb...

In G3 we are lucky to have a pretty good match for our scale/gauge. Our approximations are either 17/32nd or 13.5mm (per foot) and as it turns out these are very near the actual scale ratio of 1:22.6. Pre-CAD - I used 13.5mm as a scale converter for convenience - but these days I just draw things full-size and scale down by a factor of 22.6 - very easy to do in CAD.



Edited By IanT on 22/08/2019 21:43:10

Paul Lousick23/08/2019 00:37:31
1457 forum posts
555 photos

The scale of your model engine (ratio between the the original, full size engine to the one you are building) does not have to be exactly the same as the scale of the rails (ratio between the width between the full size rails to the model rails).

Rail gauge is simply the distance between the 2 rails. Within reason, an engine can be re-gauged, to run on different width rails by changing the distance between its wheels.

eg. In Australia the small locos used in our cane growing fields are built to 2 foot gauge rail standards and must comply with government regulations to operate, even if they are used on private property. (laws brought in place because they also travelled across public roads). This is expensive and requires a lot of paperwork. If the locos are re-gauged by changing the width between the wheels to 1'-11.7/8" they no longer comply with the government standards and can operate without restrictions on private property.


merlin24/08/2019 18:01:38
141 forum posts
1 photos

I think the modern expression is 'WOW!'

Thank you all for taking the trouble to reply.

Abutting the riverside public footpath between Shiplake and Henley is a large house and garden with a private railway running through it. The station and, so far as I remember, other model buildings are easily visible.

Is this 'park railway' likely to be 7 1/4" gauge?


IanT24/08/2019 22:07:32
1548 forum posts
144 photos

If it is Fawley Hill that you are thinking of Bill - this is a full-sized standard gauge railway on the McAlpine Estate. It's not open to the Public per se - but I've been several times as part of an invited group (I'm a member of several model railway societies).

I don't think there is a 7.25" railway there - the only one I know of in the area would be Pinewood, between Crowthorne and Wokingham (Berks). They have public running days on the third Sunday of the month during the summer and they also do a Santa Special at Christmas (much enjoyed by my Grandchildren). If you live near Henley, then it's not too far for you to go.



merlin24/08/2019 22:26:24
141 forum posts
1 photos

I think IanT might be replying to me.

The private railway track and its model buildings are easily visible through the shrubbery to the right of the public footpath. I haven't noticed the house but it must be there somewhere, between the path and the river Thames. Just after passing the property the footpath bends right to return to the river side, towards Marsh Lock and Henley.. I first saw it about 30 years ago and a friend of mine walked past it last week, hence my renewed interest. I think that Fawley Court is a huge pile on the far side of Henley.

Never mind, it is not important; I hope that this thread about scales and gauges has been informative for others as well as me.

Michael Gilligan24/08/2019 23:38:46
15886 forum posts
693 photos

A good puzzle is always worth a try:


The path now opens out on to water meadows alive with with flowers that thrive in marshland and wends its way beside the river towards Shiplake. We pass over a small bridge and alongside a garden with a miniature railway, past other large riverside homes and over the level railway crossing to Lower Shiplake. We are soon at Shiplake lock where there are permanent tents used in summer by their owners, some still in use as the season draws to an end. We cross fields of livestock and pass beside the Shiplake college boat houses with a glimpse of the college and church high up on the hill. The path narrows and follows the river closely with open views to our right looking over towards Binfield Heath.


Source: **LINK**

MichaelG. angel


Edit: Pictures here:

Edited By Michael Gilligan on 24/08/2019 23:53:33

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